Pigments are dissolved or suspended dye molecules
Biological pigments, also biochromes are substances that produce a
color resulting from selective color absorption This is different from
light emission e.g. in light bulbs in which a glowing wire emits light.
Pigment color differs from structural color
in that it is the same for all viewing angles,
whereas structural color is the result of
selective reflection because of multi-layered
structures being present.
Pigments absorb one color
& reflect another one
Colors establish social contacts,
for plants they determine even
sex partner/pollinator:
Yellow Î insects
Red
Î birds
Mineral Pigments: Vermilion
Vermilion, or vermillion, is an opaque orange-red
pigment, used since antiquity, that originally
derived from the powdered mineral cinnabar.
Chemically, the pigment is mercuric sulfide, HgS,
and like all mercury compounds it is toxic.
"China red" is another name for the pigment.
In Rome vermillion used
to color the faces of
victorious generals in
imitation of the
vermilion visage of
Jupiter Capitolinus in
the Temple on the
Capitoline Hill where
triumphant processions
came to be.
This tall brass cast
representing a
celestial Indian
damsel applying
vermilion to her
hair-parting excels,
Plant Colors & Humans
Classical Europe imported most plant stains from Asia.
Indigo. Leaves were harvested & mashed
in water. Beating the slurry aerated the mix
& precipitated the dye, then dried & shiped
Cochineal. It is a red dye obtained from scale
insects living Kermes oaks e.g in Armenia.
Insects were harvested in the fall, pressed into a
material called kermes & shipped to the west.
Wood dyes. The dark heartwood of the
Indian Sander or Sandalwood tree Pterocarpus
santalinus (Fabaceae) produced the brilliant watersoluble red of Indian textiles. An alternative source
were the pods of the Sapper tree, also an Indian
legume. Much later in History replaced by
American trees like Brazilwood & Quebracho.
Animal Pigments: Melanins
Melanins are a class of pigmented derivatives of the amino acid
tyrosine. It dissipates more than 99.9% of the absorbed UV radiation as
heat and it keeps the generation of free radicals at a minimum.
flash light passes into the eye &
reflects off the back of the eyeball.
The red-eye effect is due to melanin
in the retinal pigment epithelium
Îeffect pronounced in grey/blue eyes,
A form of melanin makes up the ink used by many cephalopods as a
defense mechanism against predators. Melanin is a photosynthetic
pigment in some fungi, enabling them to capture gamma rays and
harness energy for growth has recently been described (radiotrophic
fungus). Melanin plays a major role in the immune defense against
invading pathogens in invertebrates. Within minutes after infection,
microbes are encapsulated within melanin (melanization), and killed by
the generation of free radicals.]
Pigments of he Dark - Melanins
Pigments found in plant, animal and protista kingdoms. In animals they
are are derivatives of the amino acid tyrosine. Most common is
eumelanin = a brown-black polymer of dihydroxyindole,
dihydroxyindole carboxylic acid, and their reduced forms. Another is
pheomelanin = a red-brown polymer of benzothiazine responsible for
red hair and freckles. The increased production of melanin in human skin
called melanogenesis is stimulated by the DNA damage by UVBradiation Î leads to a delayed development of a tan.
Melanin is excellent photoprotectant
transforming harmful UV. Melanin
dissipates more than 99.9% of absorbed UV
as heat & reduces generation of free radicals
primary determinant of color in skin, hair, iris, inner ear, brain stem
Dermal melanin is produced by melanocyte cells in the epidermis. Some
ethnic groups express the melanin-producing genes more frequently,
thereby conferring a darker skin color (racism). Opposite is albinism.
Pteridines are water-soluble
compounds that result in bright
coloration like lipoph. carotenoids.
eyes of some pigeons contain
yellow fluorescing pigments
known as pteridines.[] The
bright yellow eyes of the Great
Horned Owl are thought to be
due to the presence of the
pteridine pigment xanthopterin
within certain chromatophores
(called xanthophores) located
in the iris stroma.[
Lack of Melanins Î albinoes
Total or partial lack of melanin pigments in the eyes, skin and hair.
Albinism caused by recessive alleles & occurs in mammals fish, birds,
reptiles and amphibians.
Plant Pigments
Chlorophyll is a porphyrin that absorbs red and
blue wavelengths of light while reflecting green Î
gives plants green color.
Carotenoids are insoluble red, orange, or yellow
& function as accessory pigments in plants:
carotene (an orange pigment found in carrots),
lutein (a yellow pigment found in fruits and
vegetables), and lycopene (a red pigment in
tomatoes). antioxidants
Anthocyanins (="flower blue") water-soluble
flavonoid pigments that appear red to blue, in
flowers, leaves, stems, roots, fruits, in petals up to
30% of dry weight . on underside of tropical shade
plant Tradescantia; they reflect light back to leaf
Carotenoids – more than a yellow colors
Carotenoids are lipophilic
pigments that are not soluble in
water. They are therefore not
located in the vacuoles but in the
mebrane structures of plastids
(chloroplasts & exclusively in the
chromoplasts of flower petals).
Common pigment in the many
yellow flowers of the Asteraceae
(also known as DYCs = damn
yellow composites)
Carotenoids have two classes, xanthophylls (which
contain oxygen) and carotenes (which contain no oxygen).
Carotenes are composed of two retinyl groups, that are
broken down in the small intestine into retinal, a form of
vitamin A. These pigments range from yellow to orange
(carrots, citrus fruits) to red (lycopene in tomato fruits). The
most common carotene is lutein occurring in all chloroplasts
Xanthophylls – more than a yellow colors
Xanthophylls (phylloxanthins) from Greek
xanthos (ξανθος, "yellow") + phyllon (φύλλον,
"leaf"), create yellow band in chromatography
of leaf pigments. The group of xanthophylls
includes lutein, zeaxanthin, neoxanthin,
violaxanthin, and astaxanthin.
Xanthophylls contain oxygen either as hydroxyl
groups and/or as an epoxide bridge For this
reason, they are more polar than carotenes, and
separate from carotenes in paper chromatography
Also, carotenes are more orange in color than
xanthophylls (but see Marigold with 20 % lutein)
The xanthopylls found in the bodies of animals are
ultimately derived from plant sources in the diet. For
example, the yellow color of chicken egg yolks, fat, and skin
comes from ingested xanthophylls (primarily lutein, which
is often added to chicken feed for this purpose).
Astaxanthins – more than a yellow colors
Astaxanthin belongs to the xanthophyll
subgroup of the carotenoids. Astaxanthin is
found in microalgae, yeast, salmon, trout, krill,
shrimp, crayfish, crustaceans, and the feathers
of some birds. It provides the red color of
salmon meat and cooked shellfish.
Astaxanthin, unlike some carotenoids, is not converted to
vitamin A (retinol) in the human body. While too much
vitamin A is toxic, astaxanthin has low toxicity. It is one
of the most desirable antioxidants. The primary natural
source is the green alga Haematococcus pluvialis.
Under high light & salt stress, it accumulates high levels
of astaxanthin (up to 40 g of astaxanthin in one kg algae
= 4 % dry weight.
The U.S. Food and Drug Administration (FDA) has approved astaxanthin as a
food coloring (or color additive) for specific uses in animal and fish foods only.
The European Commission considers it a natural food dye # E161
Tetra terpenoids
Conjugated DBs Æ yellow to red pigments; > 400 carotenoids
red carotenoid
astaxanthin
Plant-derived carotenoids are used
by plants:
apples,
tomatoes, banana, paprica
used by animals:
Salmon muscles, seagull beak,
lobster Î blue color humans as
Vit. A for rhodopsin production
Lipophilic pigments in resins
You know that many of the carotenoid pigments are not water-soluble.
Nevertheless they can easily stain plant parts when they appear as constituents of
the resin fluids or milky juices of plants.
Plants like the poisonwood tree Metopium
toxiforum produce resin that discolored the
bark. These colored resins are a great
source to produce unique lacquerware in
Asia and also Russia.
Chelidonium majus (greater celandine
from coeli domum = gift from heaven is a
native to Europe and western Asia.
Its latex is yellow, caused by
(1) carotenoids (chelidoxanthin) = short
yellow needles insoluble in cold but not hot
water
and perhaps
(2) alkaloids like berberine & chelidonine
Tetraterpenes
C40 compounds derive from
open ringed lycopene – the
red pigment of tomato fruits
Carotene - full ring, common
pigment of plants –
antioxidant
Lutein = in green leafy
vegetables such as spinach
and kale, employed as an
antioxidant & blue absorption
also I stored in birds; goose
fat and seagull beaks
Rhodoxanthin = xanthophyll
with purple color found in
small quantities in plants like
Taxus baccata & in the
feathers of some birds. E161f
Carotenoids in flowers and fruits
Carotenoids do not only make yellow or
orange flower but also fruits: here we can
see the yellow to red range found in
Cucurbita pepo varieties. The carotenoids
are concentrated in the fruit rind to attract
the huge and now extinct beasts that once
used to eat them & propagate their seeds.
Capsicum ssp. or bell peppers,
paprikas etc. occur in green, yellow,
orange to red varieties. The carotenoids
(red is the same lycopene as in tomato
fruits plus capsathin) are located in the
membranes of the chromoplasts.
These plastids are causing the colorful
appearance of these fruits in our eyes.
Lipophilic pigments in essential oil bodies
A tangerine Citrus reticulata rind gets its orange color from
(1) carotenoids, that are dissolved in the oil drops
plus
(2) flavonoids (anthoxanthins) inside the vacuoles of the flesh cells.
Oranges are actually a sub-tropical tree that was introduced to the American
tropics around 1500 by Christopher Columbus. In the warm South America the
oranges stay green. The orange color of Citrus sinensis (sweet orange) is brought on
by cooler temperatures. Oranges grown in Florida or California receive a bit more
cool weather than they get in Honduras.
Saffron - Crocus sativus
Saffron, has for decades been the
world's most expensive
spice,derived from the 3 dried
stigmas of the flower of the
saffron crocus (Crocus sativus).
Stigmas are dried & used in
cooking as a seasoning and
coloring agent.
Crocin – a carotenoidal glycoside
Saffron has a bitter taste & haylike fragrance; It also contains a
carotenoid dye, crocin, that gives
food a rich golden-yellow hue.
Saffron also has medicinal
applications.
Annatto
Main pigment of annatto
is cis-bixin from the redcolored resin coating of
the seeds of the tropical
bush Bixa orellana),
Cis-Bixin + NaOH Î nor-bixin
Try to make watersoluble nor-bixin
from reddish pulp which surrounds the seed of
achiote (Bixa orellana L.) - a bush of tropical
regions of the Americas. Used to color cheeses
(Cheddar, Brie), margarine, butter, rice,
smoked fish & custard powder & Indians. It
produces a red food coloring and flavor
"slightly sweet and peppery“.
Annatto oil
In a small heavy saucepan, heat
the olive oil over medium heat.
Add the annatto seeds and cook,
stirring constantly, until the oil
becomes a rich, orange-red
color, about 5 minutes. Remove
from the heat and allow to cool.
Strain the oil into a jar,
discarding the seeds, and keep
covered in the refrigerator.
Vitamin A or retinol needs plant carotene as precursor
Anthocyanins – plants’ invention of blue colors
are water-soluble vacuolar
pigments that may appear red,
purple, or blue depending on
vacuolar pH. They belong to the
subclass of flavonoids (class of
phenolics), are odorless and
flavorless. They occur in leaves,
stems, roots, flowers, and fruits.
Anthoxanthins are their clear,
white to yellow counterparts
occurring in plants.
Anthocyanins are glycosides, their
aglycons are called anthocyanidins. We
find mostly 3-glucosides of the
anthocyanidins. Anthocyanins have been
shown to act as a "sunscreen", protecting
cells from damage by absorbing UV light.
Anthocyanins – plants’ invention of blue colors
Anthocyanins are
flavonoids in petals, fruits
and vegetables that render
them vivid red to blue. To
date, there have been more
than 635 anthocyanins
identified in nature,
featuring
six common aglycones Î
& various types of
glycosylations & acylation.
Aglycones of common flavonoid subclasses
anthocyanins possess anti-inflammatory and anti-carcinogenic activity,
cardiovascular disease prevention, obesity control, and diabetes alleviation
properties, all of which are more or less associated with their potent antioxidant
property.
Anthocyanins – more than a pretty blue color
Anthocyanins are proven to be
UV-absorbing pigment.
We know for a long time that
baby plants of red foxtail
Amaranthus caudatus and red
cabbage Brassica oleracea var.
capitata f. rubra) and many other
seedlings are protected from the
sun by anthocyanins, which
together with anthoxanthins and
fluffy light-scattering hairs (.e.g
in cacti) are the principal
elements of sunscreen in plants.
Anthocyanins are more than a simple means of screening out UV. They are
also preventing the generation of free radicals by UV and blue light and their
potential damage by their potent antioxidant property.
Both anthocyanidins &
betacyanidins are
pigments that can produce
colors ranging from
yellow (470 nm) to light
red (530 nm)
Swiss chard, Beta vulgaris
alias Rhubarb chard, Ruby chard etc.
is probably one of the most pretty edible
leaves around!.
Anthocyanins + Betacyanins
Anthocyanins are sensitive to light &
high pH Î therefore extraction with
methanol & 1 % HCl. Most common
pigment in flowers & berries (blueb.,
cherries, red cabbage, Centaurea)
Identification: bathochromic shift in the
presence of Aluminium chloride
Betacyanins – the other type of water
soluble stain that can be isolated from
beetroot (betanin), cacti, bougainvillea,
pokeweed Phytolacca & Amaranthus
Betacyanins are less stable in acid,
undergo different color changes with pH
& mutually exclusive in occurrence
Heat with 2M HCl for 5 min
Î AC ok, BC loose color
Add drops of 2 M NaOH Î
AC blue-green, BC yellow
paper electrophoresis Î
AC to cathode, BC to anode
JB Harborne: Phytochemical methods, Chapman & Hall, London 1998
Betacyanins
& betaxanthins
Pokeweed
Phytolacca
Inkberry
are collectively called betalains
Betacyanins contribute
while betaxanthin contribute
purple to blue color
yellow to orange
their relative proportion in the bract determines the variation in
observed bract color in Bougainvillea, pokeweed etc.
Pokeweed Phytolacca Î Inkberry
The red-violet pigment
that occurs is a betacyanin-betaxanthin has
potential as a food
colorant. An extraction of
the saponins by butanol,
acetone and ethyl ether
was found to separate the
toxic saponin
phytolaccanin from
betanin pigments.
Saponin, phytolaccanin
believed to be the primary toxic
constituents (in berry juice and
other parts).
Alkaloids
phytolaccine (in antiviral
protein)
& phytolaccotoxin,
The eating of nonfatal quantities
of poke, perhaps of the shoots,
may cause retching or vomiting
after two hours or more.
Pokeweed berries yield a red ink or dye , which was once
used by Red Indians to decorate horses. The US Declaration
of Independence was written in fermented pokeberry juice
(hence
common
Wolfgangthe
Wickler
(1974) name
Mimicry'inkberry').
in Plants and Animals. McGraw-Hill, N.Y.
Acer or Maple leaves in sun and shade
x400. Note the dense palisade
mesophyll in this leaf that was
exposed to direct sunlight.
Note the accumulation of
anthocyanin sunscreen in the
hypodermis layer.
The palisade mesophyll is less
dense and the spongy mesophyll is
more extensive in this shaded leaf
compared to leaves on the same
tree that were exposed to direct
sun.
How and why do leaves change their color in the fall?
Fall colors
There are three colorations noticeable in fall foliage: yellow, red, and brown.
A yellow color in leaves appears after the
chlorophyll disappears from the chloroplasts,
which now are renamed into chromoplasts,
containing carotenoids (carotenes &
xanthophylls) as the only pigment.
Red leaf coloration in the fall is
like painting the “Titanic” red
after being fatally damaged by the
iceberg!
Fall colors
There are three colorations noticeable in fall foliage: yellow, red, and brown.
A brown or tan color appears in
many leaves. Molisch showed
that the brown color of oak
leaves is due to tannins and
quercetin (brown color of onion
skins). The brown turns to black
when leaves get in contact with
the minerals of the soil (see oak
leaves Î)
Other people (wikipedia) think
that the brown color is not the
result of a pigment, but rather
cell walls, which appears when
no color pigment is visible.
Fall colors
There are three colorations noticeable in fall
foliage: yellow, red, and brown.
A yellow color in leaves appears after the chlorophyll
disappears from the chloroplasts, which now have to be
renamed into chromoplasts, containing carotenoids
(carotenes & xanthophylls) as the only pigment.
Red leaf coloration in the fall is like painting the
“Titanic” red after being fatally damaged by the
iceberg!
A brown color appears in many leaves. Molisch
showed that the brown color of oak leaves is due to
tannins and quercetin (brown color of onion skins.
Other people (wikipedia) think that the brown
color is not the result of a pigment, but rather cell
walls, which appears when no color pigment is
visible.
Anthoxanthins – water-soluble yellow pigments
also known as Î flavonoids
Anthoxanthins are watersoluble flavin pigments which
range in color from white or
colorless to a creamy to yellow,
often found in petals of flowers.
They are generally whiter in an
acid medium and yellowed in an
alkaline medium. They are
chemically related to
anthocyanins as their white to
yellow counterparts .
A good example are pansies Viola doscolor.
Blue and red pansy petals contain anthocyanins
and white, yellow & orange petals contain
anthocxanthins (also called flavonoids)
Flavonoids
Quercetin, is found in capers (1800mg/kg),
lovage (1700mg/kg), apples (440mg/kg), tea
(Camellia sinensis), onion, esp. red onion
(higher concentrations in touter rings), red
grapes, citrus fruits
anti-inflammatory inhibits both manufacture &
release of histamine & other allergicmediators.
Inhibits mast cell & relieves asthma.
Rutin, is found in buckwheat] , rhubarb
Rheum & Ruta graveolens, the common rue.
glycoside between the flavonol quercetin +
disaccharide rutinose. In humans, it attaches to
iron ion Fe2+, preventing it from binding to
hydrogen peroxide, Rutin also strengthens the
capillaries reduces haemophilia
Plant Pigments
Flavonoids are water-soluble plant pigments
that have antioxidant and anti-inflammatory &
impart a yellow color ,
common flavonoids are catechin (in
strawberries & green/black teas), kaempferol
(Brussels sprouts and apples)
and quercetin, (beans, onion skin and apples)
Betalains are red or yellow water-soluble
pigments unlike anthocyanins they are indolederived from tyrosine. found only in the
Caryophyllales (including cactus and
amaranthus, red beets), never co-occur in
plants with anthocyanins. Betalains are foodcoloring agents.
Flavanol glycosides
Yellow
reduce the
cytotoxicity of
oxidized LDL
cholesterol and
lower the risk of
heart disease.
Rutin, also called rutoside, quercetin-3rutinoside and sophorin, is a citrus flavonoid
glycoside found in buckwheat , the leaves and
petioles of Rheum or rhubarb species, and the fruit
of the tree (from Brazil), as well as other sources.
Its name comes from the name of Ruta graveolens.
Rutin is the glycoside between the flavonol
quercetin and the disaccharide rutinose.
RED
The red anthraquinone rhein also
occurs in Rhubarb Rheum spp. Giving
the petales their red color and causing
antineoplastic antitumor activity.
Affects mitochondria through altered
actin microfilaments. reduce energy
supply to the cell & finally necrosis.
Cancer cells have especially high
rates of energy metabolism Î targets
Flavonoids – the signaling compounds
Flower colors : gensitein in many
brushes of the Fabacea like scotch
broom etc., lutein in dye plant Reseda
lutea, hesperetine naringenin in citrus
fruits, anthocyanins in red + blue
flowering plants
Flavonoids can be colorless or white when
at pH< 8, turn bright yellow whe exposed to
ammonia. Try with white flowers!
Some flavonoids
like gensitein
simulate & act like
estrogens Î
phytoestrogens.
How do plants protect themselves against UV?
In the thin air of high
mountains, considerably
more UV reaches the ground
than at sea level.
1. The leaves of many plants
contain anthocyanins and
flavonols like quercetin as a
natural sunscreen = UV
filter.
2. Other plants have their
leaves covered with dense
mats of fluffy hair that
reflects most of the UV
light.
The inks of the world
Ink is liquid consisting of solvents, pigments, dyes, resins,
lubricants, surfactants, fluorescers, etc.. The components of inks
serving as the ink’s carrier, colorants, to control flow, thickness ..
Carbon inks were made from lampblack or soot and gum arabic, which
keeps the carbon particles in suspension & adhered to paper. The carbon
particles do not fade over time.
e.g. India ink used in India since at least the 4th century
BC . masi was made of burnt bones, tar, pitch,
Greek/Roman writing ink: soot, glue & water
Iron gall inks in good type of ink. but corrosive & damages
paper original scores of Johann S Bach are threatened by that.
1,600 years ago : Iron salts, ferrous sulfate (made from rust),
were mixed with tannin from gallnuts and a thickener
500 years ago: varnish-like ink made of soot, turpentine, &
walnut oil was created specifically for printing
Natural inks of the world
When alarmed, octopus squirts out a cloud of inky liquid as a smoke
screen to cover its escape. It contains melanin.
Î sepia ink is from the ink sacs of cuttlefish
Sepia is a very dark brown, almost
black . At moderate dilutions, sepia
ink is quite opaque, but more dilute
washes are transparent, with red
undertones Î sepia effect. The
manufacturing process makes sepia
ink acidic, which can damage paper,
Modern process replace sepia with
modern dyes .
Sepia effect in photography is not
created by sepia ink but by bleaching,
duplicating the sepia toning effect
Other pigments
Only a few quinones are colored. They occur in mitochondria (ubiquinone) &
chloroplast (plastoquinone). Among them is also vitamin K = phylloquinone,
preventing blood clotting & bone loss.
colored naphtoquinones
juglone - a dark pigment from walnut hulls, artist
ink, dye for Confederate States uniforms
lawsone – a reddish-brown pigment from henna
Quinone Methides occur in
rosewood Terminalia. number of richly hued
timbers, often brownish with darker veining,
Colored Coleus leaves (Plectranthus) contain
pigment coleone.
Two coleone molecules form the red pigment
dracorubin of dragon blood from Dracaena
draco from the Canary islands.
Other important Pigments
Alkaloids
Berberine (yellow)
and
Sangunarin (red)
Healing Pigments: Sanguinarin & them “Red Skins”
Sanguinaria : Indian Paint. Tetterwort. Red Pucoon. Red Root. Paucon.
Coon Root. Snakebite. Sweet Slumber.
Habitat: USA & Canada, found in rich open woods
The root contains red alkaloid
(sanguinarin) that long has been
used by the American Indians as a
dye for their bodies and clothes and
has been used successfully by
American/French dyers. However,
it is killing skin cells. Plaquefighting ingredient of toothpaste.
USE: Mix a small amount of water to the bloodroot powder so that you
have a paste. like consistency. Using your finger, apply enough of the
paste to cover a wart or mole that you want to treat. Apply a bandage
over the area to insure that the paste will not be wiped off. Every two
days, apply fresh paste, and place a new bandage. Continue 2-3 weeks
Other important Pigments
Quinones
Brazil
wood
&
Anthraquinones
Chestnut - Castanea sativa Horse chestnut Hippocastanum
Native to SE Europe,
contains 5-10 % tannic acid
(= natural mordant)
Îsubtle dye from elephant grey
to parchment (beige).
ÎChestnut tannin is one of the
pyrogallol class of tannins.
ÎSince it tends to give a reddish
tone to the leather, it is often
used in combination with
quebracho.
Aesculus hippocastanum is a large
deciduous tree, commonly known
as Horse-chestnut. Native to small
area in mountains of the Balkans.
Aesculin is fluorescent whitener
saponin aescin, used for health
(varicose veins, edema)
Black Walnut Juglans nigra
Used are the hulls = exocarp or
outer coverings of the fruit
Walnut hulls are substantive or
direct dyes = no mordant required
contains > 10 % tannic acid and
quinone pigment juglone
Î Rich brown color
do not raise temps above 180 F and
10 % walnut extract
Walnut hulls gave the famous
grey color for the cotton uniforms
of the Confederate Army during
Civil War
Pyrogallol
Pyrogallol or trihydroxybenzol is a
toxic chemical. It produces free
radicals. Related to the
dihydroxybenzol Hydroquinone is
reducing agent soluble in water.
Major component in photographic
developers where it reduces silver
Pyrogallol or benzene-1,2,3triol is a white crystalline powder halides to elemental silver (black).
& reducing agent. It was first
In human medicine, hydroquinone
prepared by Scheele 1786 by
is used as a topical application in
heating gallic acid – a common
skin whitening (banned in
plant phenol. When in alkaline
European countries because of
solution pH >> 7, it absorbs
cancer risk).
water while turning purple
from a colorless solution. used
for oxygen absorption in gas
analysis. has antiseptic properties.
Plumbagin – a medicinal naphtoquinone
Plumbagin is a yellow quinone dye, formally derived
from naphthoquinone. It is a toxin or medicinal.It is
named after the plant genus Plumbago, from which it
can be isolated, also from the carnivores Drosera and
Nepenthes.
Plumbagin is antibacterial, antifungal plus a static
for prostrate cancer, Plumbagin induces cell cycle
arrest and apoptosis of cancer cells (melanoma,
prostrate etc.) through reactive oxygen species.
Plumbaginaceae or leadwort family or
plumbago family has flowering plants family
with a cosmopolitan distribution. Chalk glands
are found in this family.The family includes a
number of popular garden species.
Henna (Lawsonia inermis)
Henna is a tall shrub/tree, 2–6 m high in
family Lythraceae, native to subtropical or
semi-arid regions of Africa, southern Asia.
Henna repels some insect pests and mildew.
In Morocco, wool is dyed and ornamented
with henna, as are leather goods.
listed in Ebers Papyrus (16th c BCE Egypt)
used as hair dye in Indian court ca 400 CE, Henna,produces a redorange dye molecule,
Henna flowers have been used to create
lawsone. This molecule
perfume since ancient times,
has an affinity for
bonding with protein,
and thus has been used to
dye skin, hair,
fingernails, leather, silk
Henna - as natural sunscreen??
Lawsone (2-hydroxy-1,4naphthoquinone), also known as
hennotannic acid, is a red-orange dye
present in the leaves of the henna plant
(Lawsonia inermis) as well as jewelweed
(Impatiens balsamica).. Lawsone can
react via Michael addition with the
protein keratin in skin and hair, resulting
in a strong permanent stain that lasts until
the skin or hair is shed.
Lawsone strongly absorbs UV light,
and aqueous extracts can be effective,
sunless tanning sunscreens
Chemically, lawsone is similar to
juglone, which is found in walnuts. Both
are naphtoquinones!
Henna - as natural sunscreen??
Sunscreen (sunblock or suntan
lotion) is a lotion, spray, gel
that absorbs & reflects the sun's
UV radiation to protect the skin.
Sunscreens contain 3 main types :
•chemical UV- absorbing
compounds such as oxybenzone,
suspected photocarcinogen
•Inorganic particulates that reflect
& scatter UV light such as
titanium dioxide, zinc oxide, or a
combination of both
•Organic particulates that contain
multiple chromophores and reflect
and scatter light like inorganic
particulates, e.g.Tinosorb M.
The market offers few natural
sunscreens and yet we know that
melanins, flavonoids and
naphtoquinones like
lawsone and juglon
are excellent UVabsrobing pigments
there is a chance
Tattooing – an ancient art
Traditional tattooing involves the breaking of
the skin stick and poke" is keeping tip of a
sewing needle saturated with ink, the skin is
pricked over and over, creating a design.
Risk of infection and the permanence of a
tattoo that may be later embarrassing. The use Henna,produces a
red-orange dye
of mostly synthetic tar dyes – and yes this
molecule, lawsone.
includes carbon black – another concern.
This molecule has an
affinity for bonding
with protein in the
epidermis and does
not need the
implantation into
deeper layers.
Botanical Jewelry: Seeds
Beauty & Toxicity are often close together
The garden bean Phaseolus (upper
panel) has multiple color varieties
in its native Ecuador. Also kidney
beans (2) do not have to be red and
lima beans (3rd panel) occur in
many shades other than white.
Voila, the toxic (hemagglutinins) but
soooo oh irresistably pretty seeds of the
1. rosary pea Abrus precatorius,
2. unique castor beans Ricinus communis
3. coral bean Adenanthera pavonina.
http://waynesword.palomar.edu/ww0901.htm
Botanical Jewelry http://waynesword.palomar.edu/ww0901.htm
Most people think of natural jewelry as shiny pieces of corals, pearls and precious
or semiprecious stones, polished and set in gold or silver. Who would ever believe
that some of the most unusual and striking jewelry in the world comes from plants?
Most bot. jewelry is made from seeds which are drilled and strung into necklaces
Ear rings in dolphin shape made from
the exploded seed of the toxic plant
Hura crepitans – the sandbox tree
Arango created his bold jewelry from
tagua nuts, a botanical alternative to
ivory (a.k.a. vegetable ivory), a seed
that comes from the ivory-nut palm or
tagua palm which grows in the humid
tropical forest of South America.
The Red Anthraquinones
Madder (Rubia tinctorum) Î alizarin red
Alizarin is an anthraquinone
originally derived from roots of
the madder plant. Tut’s cloth had
it. 1869 first pigment to be
duplicated synthetically. Related
dyes: Alizarine Cyanine Green G
Alizarine Brilliant Blue R
Madder is the common name of
Rubia, a genus of 60 species of
perennial climbing native to Old
+ New world: Common Madder
(Rubia tinctorum), Wild Madder
(Rubia peregrina), and Indian
Madder (Rubia cordifolia).
Rhubarb anthraquinones
Rhein occurs in Rhubarb Rheum spp. & other purgatives.
Antineoplastic antitumor. Appears to affect the membranes of cells &
mitochondria & finally to disrupt them. Action occurs through altered
actin microfilaments collapsing into ring-like structures. Altered
mitochondria reduce energy supply to the cell & finally necrosis.
Cancer cells have especially high rates of energy metabolism & are
preferred targets.!!!
Flower Pigments
Other common names include Weld (Reseda
luteola), Dyer's Rocket, dyer’s broom, is a
European plant with long spikes of small, yellowishgreen flowers cultivated as a source of yellow dye
Calendula officinalis, Pot Marigold, Asteraceae. native to southern
Europe. The petals and pollen of Calendula officinalis contain the
carotenoids flavoxanthin and auroxanthin as antioxidants, & source
of their yellow-orange coloration. The carotenes promote the
renewal of skin tissue + antibacterial properties prevent infections.
As a rinse for the hair, pot marigold gives a golden tinge to fair
hair: Viking women used it to dye their hair & textiles yellow.
Tanacetum vulgare, Tansy, Roundish, button-like, yellow flower
heads in terminal clusters from mid-to-late summer. Traditional
dyers use both tansy leaves & flower buttons to produce a goldenyellow color (flavonoids). For 100 grams wool you need 300
grams tansy. The plant can also be dried. Before dyeing simmer
wool for 1 h at 90 C in alum solution. 20 g alum for 100 g yarn.
Flowers to Color Î Marigold petals do not fade
Marigold (Calendula officinalis) in Asteraceae,
native to Iran. not to be confused with other
marigolds, such as Tagetes, corn or marsh marigolds.
Petals used to add color to salads (carotenes, 80 %
lutein + flavins), extract is common food additive to
produce darker egg yolks. Aroma not sweet,
resembles hops in beer. The oil from its seed
contains calendic acid.
Once used as blond hair dye, still wholesome
coloring agent in for cheese, soups & salads +
textiles: for 110 g cotton/wool: Needs previous
1 h cooking in mordant: 30 g alum + 10 g
tartaric acid in 300 ml water. Transfer to
simmering solution of 250 g flowering heads,
cover with water & boil until right color is
achieved.
Perfume oil of patchouli
Gipsywort Lycopus europaeus
Used by Gipsy women to keep
their hair black.
Herb yields dark pigment
Gypsies were reputed to stain their
skin with the juice of the plant,
althgough Howard (1987) states
that they used it to dye their linen
Extract red- todark brown
pigment with
hot water.
Nature of
pigment
unknown!
plant melanin??
Dyeing with Plant Dyes
Many dye plants need no mordants since they
contain lots of tannins on their own.
Lichens, Black Walnut fruit hulls, Oak
acorns, alder catkins, sumac berries etc.
Dyes like tumeric, beets , blueberries, apple
peels, cherries etc. need mordants to become
permanent 7 stand up to fade & wash testing.
Mordants are substances that bind or fix the
dye permanently to the fibers.
Most common mordants are
(1) ALUM=
Al, K, NH3 sulfates normally used 1,5 g / l
& CREAM of TARTAR (= tartaric acid, i.e.
wine acid, normally used at 2.5 g / l
No mordants needed
Madder (Rubia tinctorum) Î alizarin red
Alizarin is an anthraquinone
originally derived from roots of
the madder plant. Tut’s cloth had
it. 1869 first pigment to be
duplicated synthetically. Related
dyes: Alizarine Cyanine Green G
Alizarine Brilliant Blue R
Madder is the common name of
Rubia, a genus of 60 species of
perennial climbing native to Old
+ New world: Common Madder
(Rubia tinctorum), Wild Madder
(Rubia peregrina), and Indian
Madder (Rubia cordifolia).
Logwood tree (Haematoxylum campechianum)
Logwood tree (Haematoxylum
campechianum grows in Central America &
led to founding of Belize from British
logging camps of 17th century. an important
histological stain. (H. + Eosin = popular for
animal cells
Related to Brazilin - red
pigment from brazilwood
Caesalpinia. Natural red 24
= dye for fabric, paints, inks
in acidic sol yellow, alk red
Haematoxylin, hematoxylin, Natural Black 1, or
C.I. 75290 extracted from the wood of the tree.
oxidised it forms haematein = blue-purple color,
used, together with a suitable mordant (Fe(III) or
Al(III) salts), to stain cell nuclei. Structures that stain
with haematoxylin are called basophilic.
Dyeing with Natural Pigments
Nothing is more colorful than flowers, insects and birds. However,
early humans must have been frustrated to realize that the dyes
from insects and birds cannot be extracted.
Exceptions confirm the rule:
cochineal, a red dye, + Lac, a scarlet dye is made from ground up
insects.: carmine comes from cochineal (natural red 4) lac (natural red
25) and hematein which comes from the logwood tree (natural black 1).
Tyrian purple was an expensive dye in antiquity extracted from the
aquatic mollusk Murex brandaris. imperial purple is a purple-red dye
which was first produced by the ancient Phoenicians in the city of Tyre.
Dyeing with Natural Pigments
Most plant pigments used for dyeing cloth are
anthroquinones!
Indigo Indigofera tinctoria (As) or suffrutinosa (SAm)
Indigo as in blue jeans (Strauss 1873)
Is challenging dye to use because it is
not soluble in water; to be dissolved,
water must be free of oxygen.
In temperate climates
indigo is obtained from
woad (Isatis tinctoria) and dyer's
knotweed (Polygonum tinctorum).
BASF developed a commercially
feasible manufacturing process in
1897, by 1913 natural indigo had
been almost entirely replaced
India was supplier to Europe as
early as Roman era. Association of
India with indigo is reflected in
Latin word indicum, for the dye
Extraction of indigotin from leaves:
extraction in O2-free alkali turns
water blue in 24 h. Aeration
(paddling) precipitates indigotin.
Blue sludge is dried and sold.
Requires no mordant, but alkaline
(add 1 TBS alkali NaOH to 1 l water
pH 10-11 + 1 oz of indigo powder) &
O2-free bath (add 1 TBS thiourea
dioxide or Na hydrosulfite). Wait 15
min to reduce & mix Î solution
turns from transparent green-yellow
to blue showing oxidized form. Test
by dripping some solution on paper.
Cotton requires pH 11.
It follows a series of
important dye plants
including and introducing
The dyes and ingredients of
our dyes box from Earthues
Woad (Isatis tinctoria )
Woad biennial in family Brassicaceae
Woad also name of the blue dye. The
blue pigment indican is the same as in
indig, it is insoluble in water, alcohol,
but soluble in chloroform, H2 SO4
leaves crushed with wooden rollers,kneaded into 3-inch-diameter balls.
This gave the workers black hands. balls were dried and ground into
powder piled into deep layers. layers were watered to ferment
(breakdown of indican, a glycoside - to dyestuff indigotine) producing
horribly foul odors from sulfur-containing glucobrassicins . After two
weeks of fermentation, the leaves dried; powder contained indigotine
woad might prevent cancer, having
more than 20 times more glucobrassicin
than broccoli. Young leaves when
damaged can produce even more
glucobrassicin, up to 65 times as much
Alkanet - Pentaglossum sempervirens
From the Arabic Alkanna ( a
term for henna).
The root has a red unidentified
pigment. The leaves have highly
poisonous alkaloids
Anthraquinone resorcinol-type pigment is easily extracted from Alkanet
root by oil & ethanol. It imparts a ruby red color to natural fibers,
wool, wood, stone, lip balm, lipstick, ointments, salve, soap, lotion, and
to tint oils, vinegar, tinctures, varnishes, or wine. In the past, it was used
to improve the appearance of low quality wines and ports, and to give an
aged appearance to wine corks. In soap, it will yield shades of pink,
blue, and purple, depending upon the amount used, types of oil used,
and the alkalinity of the soap
Madder (Rubia tinctorum) Î alizarin red
Alizarin is an anthraquinone
originally derived from roots of
the madder plant. Tut’s cloth had
it. 1869 first pigment to be
duplicated synthetically. Related
dyes: Alizarine Cyanine Green G
Alizarine Brilliant Blue R
Madder is the common name of
Rubia, a genus of 60 species of
perennial climbing native to Old
+ New world: Common Madder
(Rubia tinctorum), Wild Madder
(Rubia peregrina), and Indian
Madder (Rubia cordifolia).
Weld: Reseda luteola + R. odorata
Mignonette (Reseda) is a genus of
fragrant herbaceous plants native
to the Mediterranean region The
species include annuals, biennials
and perennials, and grow to 40130 cm tall. Flowers are produced
in a slender spike, each flower
small (4-6 mm diameter), white,
yellow, orange, or green, with four
to six petals. The volatile oil is
used in perfumery.
Other species is Weld (R.
luteola), Dyer's Rocket
The yellow dye was obtained
from the roots of R. luteola by
the first millennium or 900 BC
Pigment is a Flavonoid: 2 % of the dry
weight
Plant material extracted with hot water,
add wool or silk to to extract and
simmer at max. 80°C
cutch – Acacia catechu – a wood dye
Cutch tree is native to India is
used for many purposes breath
freshener & diuretic
The wood is chipped and boiled,
the sap dissolves & liquid becomes
syrupy. Liquid is cooled, pressed,
cut into pieces & ground into
powder
When dyeing with cutch extract
the dye becomes not only deeper
but redder the more it is simmered.
Other wood dyes:
Logwood Heamatoxylon, red alder
Alnus rubra, red sandalwood,
fustic Chlorophora etc.
Dye for all fibers :
with alumÎ yellow-to-red brown
with iron sulfate Î black-brown
with soda ash=Na carbonate Î red
Carminic acid & Scleranthus perennis
Carminic acid is a red glucosidal
anthraquinone structure that occurs
naturally in some scale insects such as
the Mexican or Polish cochineal.
insects prod. acid as feeding deterrent.
Carminic acid is pigment in carmine.
= C.I. 75470 and C.I. Natural Red 4.
Perennial knawel (Scleranthus
perennis ) is a perennial herb of the
carnation family. It grows on sandy,
dry, acidic soils of Central Europe.
Polish carmine
scales are used to
produce a crimson
dye colloquially
known as Saint
John's blood.
larvae of P.
polonica live on
the roots of various
herbs – esp. knawel
(from Knauelkraut
German)
Logwood and hematoxylin
Haematoxylin, hematoxylin, Natural
Black 1, or C.I. 75290 is extracted
from the wood of the logwood tree.
When oxidised it forms haematein, a
compound with rich blue-purple
color, and is used, together with a
suitable mordant (most commonly
Fe(III) or Al(III) salts), to stain cell
nuclei for examination under a
microscope. Structures that stain with
haematoxylin are called basophilic.
Brazilin is a red quinone
pigment obtained from the
wood of the brazilwood family
(Caesalpinia sp), and is also
known as Natural red 24.
Brazilin has been used since
at least the middle ages to
dye fabric, for paints and inks
The specific color produced by the pigment depends on its manner of
preparation: in an acidic solution brazilin will appear yellow, but in an
alkaline preparation it will appear red. Brazilin is closely related to the
blue-black dye haematoxylin, having one less hydroxyl group.
Logwood tree (Haematoxylum campechianum)
Logwood tree (Haematoxylum
campechianum grows in Central America &
led to founding of Belize from British
logging camps of 17th century. an important
histological stain. (H. + Eosin = popular for
animal cells
Related to Brazilin - red
pigment from brazilwood
Caesalpinia. Natural red 24
= dye for fabric, paints, inks
in acidic sol yellow, alk red
Haematoxylin, hematoxylin, Natural Black 1, or
C.I. 75290 extracted from the wood of the tree.
oxidised it forms haematein = blue-purple color,
used, together with a suitable mordant (Fe(III) or
Al(III) salts), to stain cell nuclei. Structures that stain
with haematoxylin are called basophilic.
Flower Pigments
Safflower flower heads are dried & used for
colouring foods & clothing, and making red
(carthamin) & yellow dyes (carhamidin – a
flavonoid),
The roots of the madder plant Rubia tinctorum
supply the coloring substances that are converted
to madder lakes, the principle coloring substance
which is alizarin. The shades of colors vary from
scarlet (stannous madder lakes), carmine red (to
red with a bluish tint (alizarin lakes).
Dyers’ Chamomile (Anthemis tinctoria)
Beautiful daisy flowers which yield a strong
yellow dye, the flower heads are harvested and
used when freshly picked or dried for winter
storage.
Flower Pigments
Other common names include Weld (Reseda
luteola), Dyer's Rocket, dyer’s broom, is a
European plant with long spikes of small, yellowishgreen flowers cultivated as a source of yellow dye
Calendula officinalis, Pot Marigold, Asteraceae. native to southern
Europe. The petals and pollen of Calendula officinalis contain the
carotenoids flavoxanthin and auroxanthin as antioxidants, & source
of their yellow-orange coloration. The carotenes promote the
renewal of skin tissue + antibacterial properties prevent infections.
As a rinse for the hair, pot marigold gives a golden tinge to fair
hair: Viking women used it to dye their hair & textiles yellow.
Tanacetum vulgare, Tansy, Roundish, button-like, yellow flower
heads in terminal clusters from mid-to-late summer. Traditional
dyers use both tansy leaves & flower buttons to produce a goldenyellow color (flavonoids). For 100 grams wool you need 300
grams tansy. The plant can also be dried. Before dyeing simmer
wool for 1 h at 90 C in alum solution. 20 g alum for 100 g yarn.
Flowers to Color Î Marigold petals do not fade
Marigold (Calendula officinalis) in Asteraceae,
native to Iran. not to be confused with other
marigolds, such as Tagetes, corn or marsh marigolds.
Petals used to add color to salads (carotenes, 80 %
lutein + flavins), extract is common food additive to
produce darker egg yolks. Aroma not sweet,
resembles hops in beer. The oil from its seed
contains calendic acid.
Once used as blond hair dye, still wholesome
coloring agent in for cheese, soups & salads +
textiles: for 110 g cotton/wool: Needs previous
1 h cooking in mordant: 30 g alum + 10 g
tartaric acid in 300 ml water. Transfer to
simmering solution of 250 g flowering heads,
cover with water & boil until right color is
achieved.
Perfume oil of patchouli
Gipsywort Lycopus europaeus
Used by Gipsy women to keep
their hair black.
Herb yields dark pigment
Gypsies were reputed to stain their
skin with the juice of the plant,
althgough Howard (1987) states
that they used it to dye their linen
Extract red- todark brown
pigment with
hot water.
Nature of
pigment
unknown!
plant melanin??
Dyeing with Plant Dyes
Many dye plants need no mordants since they
contain lots of tannins on their own.
Lichens, Black Walnut fruit hulls, Oak
acorns, alder catkins, sumac berries etc.
Dyes like tumeric, beets , blueberries, apple
peels, cherries etc. need mordants to become
permanent 7 stand up to fade & wash testing.
Mordants are substances that bind or fix the
dye permanently to the fibers.
Most common mordants are
(1) ALUM=
Al, K, NH3 sulfates normally used 1,5 g / l
& CREAM of TARTAR (= tartaric acid, i.e.
wine acid, normally used at 2.5 g / l
No mordants needed
Which Pigment colors which Flowers?
Structural color
Raleigh Scattering of light by tiny
particles generates brilliant white,
bright green, and bright blue hues
As light moves through the atmosphere,
most of the longer wavelengths pass
straight through. Red, orange and
yellow light is little affected by the air
particles.
As you look closer to the horizon, the sky
appears much paler in color. To reach
you, the scattered blue light must pass
through more air. Some of it gets
scattered away again in other
directions. Less blue light reaches your
eyes. The color of the sky near the
horizon appears paler or white.
Structural Colors
Unlike homogeneous pigment colors
A structural color is different for
different viewing angles,
structural color is the result of
selective reflection because of
multi-layered structures
The rainbow
Theoderic of Freiburg: De iride = On the
Rainbow; born 1250 studied in Paris,
Domican priest preached in the vernacular,
i.e. in German, modeled raindrop in hexag.
urine flasks Î refraction + reflection
Refraction is when red , blue ..light is slowed in glass
or water of a raindrop. Red is bent less than blue. Red
+blue are reflected inside of the drop (mirror) , but at
different angles, so that
red appears above
yellow, green & blue in
rainbow, but not in prism
Double reflection leads
to secondary rainbow
Ref: ROM Harre: Great Scientific Experiments; twenty experiments
that changed our view of the world. Oxford University Press 1983
Observer
sees only
reflection
of drops at
angles of
40- 42°
Blue & grey eyes contain
low amounts of melanin
within iris stroma longer
wavelengths of light
tend to be absorbed by
the underlying iris
pigment epithelium, &
shorter wavelengths
are reflected scattered.
Inheritance pattern is similar
to that of a recessive trait, but
it is controlled by interactions of
several genes. Mutation may
have arisen in a single girl
6,000-10,000 years ago during
the neolithic revolution. Blue
eyes are now most common in
N & C Europe.
Structural colors in plants ?
The petals of pansies Viola get
their velvet sheen from vertical
emanation of the epidermis – a
structural effect.
The leaf or petal surface
Recently (1990) the surface features of leaves
and petals have been “rediscovered”. As the
second picture shows this was “no news” to
Botanists of the outgoing 19th century.
Scientific progress goes in strange cycles, partially driven by curiosity
but recently more by practical interest in nature-inspired engineering.
Structural colors in plants ?
Viburnum tinus fruits turn from
red into structural blue without
ever producing a blue pigment.
This color looks almost iridescent,
and it is yet to be shown whether it
is caused by wax emanations at the
cuticle. All you need is an SEM …
Botanical Jewelry http://waynesword.palomar.edu/ww0901.htm
Fruits of rudraksha
(Ruda’s = Shiva’s eyes)
Elaeocarpus angustifolius
have an iridescent blue
coating, which is used as a
prayer bead and good-luck
charm by religious hindus
like the sadhu on the right.
The fruits are 2 cm in
diameter and are coated with
a wax that scatters blue light
similar to what we know
from Laurintinus berry
Viburnum tinus.
The seeds have many
faces ( the faces of Shiva,
see below)
Why do buttercups have shiny petals?
Yellow buttercup blooms.
Buttercups, Ranunculus, are a bright
yellow, shiny flower. The shiny surface
of the petals is due to a special layer
of reflective cells beneath the petal's
surface cells.
This sunny, cheerful
flower is actually
poisonous, and can
cause skin irritation. They
should never been eaten
Petals
The shape of the epidermis cells is a hidden feature. I never suspected that
the velvety appearance of French marigold and pansy flowers was due to
cone-shaped epidermal cells.
Cone-shaped pansy petals form Viola tricolor
Chrysanthemum, and Helianthus, Primula
Petals
Today all
engineers are
very eager to
simulate the
cone-shaped
surfaces
found in
leaves and
petals of
plants –
The shape of
epidermis cells in
Cosmos
atrosanguineus
(1a–1c),
Dahlia pinnata
(2a–2c),
biomimetics
Rosa chinensis
(3a–3c)
pansy Viola tricolor
(4a–4c).
Some examples of flowers with cone-shaped epidermis cells
Leaves with lenses
Anthurium is a genus in the skunk cabbage family or Araceae. The leaves are soft like
velvet and you find here curved epidermis cells acting like lenses to focus the light on
the chloroplasts that are situated in the first subepidermal layer, see microscopic picture
photographed through the peeled epidermis.
Structural colors in plants
Gray and blue hues of leaves as in Aloe
plicatilis, agave, cedars and cacti is
produced by the presence of thick wax
together with contours of the epidermal
cells (microrelief); e.g. conical
projections+ very thick cell walls in
agaves. They form a loose surface wax,
called epicuticular wax, which is very
reflective .
Rubbing the powdery wax from the
surface reveals the green leaf color
beneath.
In some plants this fails: the bluish leaf
hues of a desert mahonia, Berberis
trifoliolata, has real microscopic, nipplelike projections.
Structural colors in plants
Hawaian
Silversword,
a rare endemic
White Salvia
or sage
A form of structural color is in Reflective Leaves:
Whitish, silvery, and other metallic f leaf coloration to silver and white
are due to nonliving plant hairs (trichomes). Dry, dense nonglandular
trichomes tend to be the most reflectant. Thoroughly studied is the
reflectant leaf type of desert brittlebush (Encelia farinosa), a desert
perennial of western North America having silver leaves several degrees
cooler than the same leaves without.
Interference Colors
Bird feathers are truly iridescent changing their color depending
on the angle of the light they are hit by:
Why can a mallard head change from green to purple?
Feathers and hair are made of dead
cells with lots of the protein keratin
surrounding melanine pigments .
Some weak light passes through the
transparent keratin layer while in bright
sunlight other light waves are reflected
(and polarized) by it. This leads to the
reflection of 2 different sets
wavelengths.
Depending on intensity and angle one
or the other will dominate your vision.
What makes a butterfly
wing so colorful?
Well, …. it is not a multitude of
pigments. The iridescent colors derive
from a grit pattern that amplifies or
extinguishes wavelength like a
monochromatic interference filter.
Iridescence – pretty & meaningful
Morpho butterfly has no blue pigment but shiny blue feathers
Peacocks need females to have the sun behind them to show off their feathers
Scarab beetles reflect circularly polarized light
Î all these colors are caused by geometrical surface patterns !!
These surfaces can be modified into sensors that change
color in the presence of some dangerous chemical.
H. Ghiradella
showed many
SEM images
of fluorescent
anim surfaces
looking like
conifer trees,
honeycombs,
bristles etc.
Colored Microscopy – interference filters
Ordinary light consists of a bundle
of rays having different wavelengths
& different vibration directions but
share a common direction of
propagation.
Interference or dichroic filters are
not based on absorbing one or more
colors of the spectrum maintaining a
nearly zero coefficient of absorption
for all wavelengths. By reflecting
many spectral bands it transmits &
reinforces a very narrow band of
choice. This gives the IF its color.
An interference filter consists of multiple thin layers with different refractive
indices. Interference takes place between the incident and reflected waves at
the thin-film boundaries. Reflection & transmission at many identical layers at
identical thickness leads to the reinforcement of one transmitted band.
Interference colors in plants– watch for metallic sheen
Viburnum tinus fruits turn from
red into structural blue without
ever producing a blue pigment.
This color looks almost iridescent,
and it is yet to be shown whether it
is caused by wax emanations at the
cuticle. All you need is an SEM …
Interference colors – watch for metallic sheen
The metallic sheen of these plants from
the under story plant is a signature for
interference colors. Another sign is that
the color changes in dependence of the
angle from which you are looking.
The blue color of this
understory Selaginella or
spike moss plant is caused
by the combination of
cuticular structure on top of
a dark-green mesophyll
Strobilanthes dyeri from the
understory of the djungle
Iridescence in leaves
The spectacular blue color of the
Colorado Blue Spruce =
Engelmann spruce or Picea
engelmannii is caused by small wax
particles which preferentially scatter
blue light into your eyes. Î “Mom!”
Although these particles are difficult
to see in light microscopy (we will
try it anyway!) they are visible with a
scanning electron microscope = SEM
Iridescent blue in young fern fronds in
Danaea nodosa from the understory of the
rain forest of New world tropics.
Constructive interference is caused by a
unique epidermal cell wall that has
multiple layers.
Iridescence in leaves
Iridescent blue in young fern
fronds in Danaea nodosa caused
by constructive interference is
caused by a unique epidermal cell
wall that has multiple layers.
The interference in these plants is achieved by
the deposition of successive layers of cellulose
fibrils at a slightly different angle creating a
changing refractive index and a polarizing of
the reflected light.
Yes, wear your polarizing sunglasses and
convince yourself that this is a unique example
of a plant with the ability to polarize light.
Human & animal vision: “what do they see …?”
The cones with their modified retinal
receptor allow humans to see color, but not
UV, polarization (insects), not IR (vipers)
Most other
mammals
cannot see
color but
have a
contrastbased gray
vision
Plant Colors & Animals
Not all creatures see the same world, your honor! You for example, do
not see the UV signs on the document! But, they are really there
Not all mammals can
see color, but we
primates can. The best
mammal though is a fruit
bat seeing UV as well.
So do many
insects (swallowtails!)
birds and
fishes.
“ But, mom, I thought we
are the most advanced
species?
A…fruit bat! Really?”
What we see under
water is not …real?
This is real !
Red Algae hold the record of depth in the sea
Red algae grow much deeper than
other algae since they have an
auxiliary pigment called
phycoerythrin.
A research sub found red algae
growing in virtual darkness
at 268 m below ocean surface.
These purple algae are crustose. algae
changed concept that light of < 1%
intensity (ca. 215 m depth) is
absolute limit for photosynthesis.
The red tide is caused by a pigment
from dinoflagellate, not red algae
caused by carotenoids.
Physiology or Psychology of Colors
Color has an astounding effect on perceptions & feelings.
Different colors evoke different memories & ideas.
For instance in China the color red
tends to make people feel calm, while
in America red tends to make people
more aggressive. Î effect of color on
a persons mind is perceptual, rather
then being physiological & inherent
Î an effect of social training of the
individual
Therefore people dislike unusual
combinations of food, furniture bed
sheets etc with unusual colors.
Examples: green or yellow caviar
or sauerkraut, green or black bed
sheets, green or spotted TV sets ….
Here is what Joe the Plumber thinks:
Black is an attention grabber; it also makes rooms look
small and seem restrictive. It darkens a person’s mood
Red is an exciting color. Red makes Americans aggressive. It speeds up
their metabolism and gives them energy & inspiration
White is uninspiring; it is the generic look for many offices. Good color
for warm climates as it reflects light creating cool and breezy feeling
The earth tones (browns, oranges, & yellow) Browns cause feeling of
ease & belongingness & safety, and family.
Blue & green evoke serenity and peace associated with nature & ocean
Orange makes people happy, stimulates appetite
Yellow creates a short-term positive effect on the
psychology of people.Long exposure can lead to irritation.
Green is the color of growth, freshness, & welcome
Pink is an extreme calming color: one finds it
impossible to act aggressively against pink creatures Î
Colors & what they are good for (color microscopy)
Blue (450 to 520 nm) is best fro contrasting coastlines &
. difference between evergreens and deciduous trees
Green (520 to 600 nm) is best for seeing water pollution
,
sediments and mapping reefs
Red (760 nm to 690 nm) best for telling difference
between certain plants, or city/country outlines from sats
Near-Infrared (760 to 900 nm goes to ) is best for .
viewing plant life. Healthy plant leaves are highly
reflective in this range!
Mid-Infra-red (1.55 to 1.75 μm) is used to measure the
amount of moisture in air & porometers for transpiration
2nd Mid-Infrared (2.08 to 2.35 μm) is is used to
The Subconscious Importance of food Color
Why adding dyes to products:
People associate certain colors with certain flavors,
the color of food can influence the perceived flavor
Aim is to simulate the color expected by consumer to be
natural such as adding red coloring to glacé cherries
(would otherwise be beige), but also just for effect, like
green ketchup Heinz launched in 2000.
Few people know that seemingly "natural" foods such as
orange & salmon are also dyed to mask natural variations
Some of the primary reasons include:
Offsetting color loss due to light, air,
temperature, moisture, storage conditions
Masking natural variations in color.
Enhancing naturally occurring colors.
Providing identity to foods
Protecting flavors from damage by light
Maraschino cherries are preserved
in brine + sulfur dioxide or alcohol,
then soaked in a suspension of red
food dye FD&C Red 40 +sugar
syrup, artificial almond flavor,
while cherries dyed green by
combination of FD&C Blue 1 &
FD&C Yellow 5 are sometimes
peppermint-flavored.
Subconscious effects of Color on Taste
If cherries, & beetroot
were snowy white
instead of red, would
they taste the same to us
Would chocolate taste
different if it were
bright blue?
Do garden peas and
spinach have an
intrinsically green taste?
Green caviar, chocolate, meat, blue fish meat
There is no actual correlation between color and taste, but there is a
perceived one., if something was dirt brown and not chocolate, we'd be
very put off, even if it tasted the same as our favorite fruitcake.
Food presented in an unorthodox manner is dismissed as disgusting
Food Colors
In
FD&C
that
has approved
colorant
AnUS,
antigen
is aindicates
substance
thatFDA
is a close
enough fit
to bindfor
to use
the in
specific
Foods,
Drugs
and Cosmetics: numbers are given to synthetic food dyes.
site of an
antibody.
In EU, E numbers for all approved additives, both synthetic & natural,
An
allergen
is are
a substance
that to
binds
to specific
site of an
antibody
Natural
colors
not required
be tested
by a number
of IgE
regulatory
bodies throughout the world, including the United States FDA.
Color Additives Permitted For Direct Addition To Human Food (USA)
Certifiable Colors
FD&C Blue No.1 (Dye and Lake),
FD&C Blue No.2 (Dye and Lake),
Green No.3 (Dye and Lake),
FD&C Red No.3 (Dye),
FD&C Red No.40 (Dye and Lake),
FD&C Yellow No.5 (Dye and Lake),
Yellow No.6 (Dye and Lake),
Citrus Red No.2*
* restricted to specific juices
Colors Exempt from Certification
Annatto extract, B-Apo-8'-carotenal*,
Beta-carotene, Beet powder, FD&C
Canthaxanthin, Caramel color,
Carrot oil,
Cochineal extract (carmine);
Cottonseed flour, toasted FD&C
Ferrous gluconate *, Orange B*,
Grape color extract*, Grape skin extract*
Paprika, Paprika oleoresin
Riboflavin, Saffron, Titanium dioxide*,
Turmeric, Turmeric oleoresin,
Fruit juice, Vegetable juice
Common Uses of Artificial Food Colors
Common Food Uses
FD&C Blue No.1
Brilliant Blue FCF Bright blue
dairy products powders, jellies, confections
Beverages condiments, icings, syrups,
FD&C Blue No.2
IndigotineRoyal Blue
Baked goods, cereals, snack foods, ice cream,
confections, cherries
FD&C Green No.3
Fast Green FCF Sea Green,
Beverages, puddings, ice cream, sherbert
cherries, confections, baked goods, dairy FD&C
Red No.40
Allura Red AC Orange-red
FD&C Red No.3
ErythrosineCherry
FD&C Yellow No.5
TartrazineLemon Yellow,
FD&C Yellow No.6
Sunset YellowOrange,
Gelatins, puddings, dairy products,
confections, beverages, condiments
red Cherries in fruit cocktail and in canned
fruits for salads, confections, baked goods,
dairy products,
Custards, beverages, ice cream
confections, preserves, cereals
Cereals, baked goods, snack foods, ice cream
beverages, dessert powders, confections
Natural food dyes
Annatto E160 cis-bixin + norbixin from red-colored resin coating of the
seeds of tropical bush Bixa orellana) in cheese, oil, butter, smoked fish
Anthocyanins E 163 common red + blue pigment of most flowers, fruits
Betalains E162 red pigment of beetroots, Swiss Chard, pokeweed,
Curcumin E100, yellow pigment of turmeric spice, not water-soluble
Cochineal E120: insect-cactus-derived red pigment from crushing
female Dactilopius coccus insects, expensive rel. to carminic acid
Orcinol E121, red pigment derived from lichen Rocella tinctoria
converted to orcein (red-brown microscopic dye), with ammonia to
orchil – a blue pigment
Carbon black E153 charcoal from plants & animals in liquorice, jam ...
Capsanthin E160 capsorubin extract from paprika pepper, in eggs, meat
Caramel E150 brown ammonia-treated sucrose in beer, wine, bread, …
Natural food dyes
Carotene cis-bixin + norbixin from red-colored resin coating of the
seeds of tropical bush Bixa orellana) in cheese, oil, butter, smoked fish
Lycopene E160 common red + blue pigment of most flowers, fruits
Chlorophyllin E140 in sweets, soups Copper chlorophyllins repl Mg
& are more stable & water soluble olive-green dye
Lutein red pigment derived from lichen Rocella tinctoria converted to
orcein (red-brown microscopic dye), with ammonia to orchil – a blue
pigment
Chlorophyllin E140 in sweets, soups Copper chlorophyllins repl Mg
& are more stable & water soluble olive-green dye
Rhodoxanthin charcoal from plants & animals in liquorice, jam etc
Saffron capsorubin extract from paprika peppers, in eggs, meat
Violaxanthin brown ammonia-treated sucrose in beer, wine, bread, …
Caramel
Caramel is made by heating sugar slowly to around 170 °C (338 °F).
As the sugar approaches this temperature, it melts proceeding to
isomerization & polymerization of the sugars into various high-weight
compounds providing the dark color. Fragmentation reactions result in
volatile low- molecular-weight compounds that create flavor together
with difructose-anhydride. Candies & desserts made with caramel.
Caramel apples or taffy apples
are created by dipping or rolling
apples-on-a-stick in hot caramel,
then rolling them in nuts or other
stuff, and allowing them to cool.
4 cups sugar in sauce pan, add 2 cups water, heat to 170 C water will evaporate, solutin
goes through var stages, watch for brown color, stop because it blackens quickly
Analysis with Natural Pigments
Litmus is water-soluble mixture of different dyes extracted
from lichens, especially Roccella tinctoria, Orchella weeed
or orchil. The mixture has CAS number 1393-92-6. If
absorbed onto filter paper. it becomes a pH indicator.
Cudbearobtained from the lichens
Ochrolechia. Lichen dyes were dissolved in
human urine Î gyrophoric acid –yellow dye
Wolfbane lichen (Letharia vulpina), a
fruticose lichen that grows on the bark of pines,
contains a mildly toxic yellow dye called
vulpinic acid.
A brownish dye from the foliose lichen
Parmelia omphalodes is used on hand-woven
Harris tweeds from Scotland..
Indicator
Gentian
violet
yellow
Low pH
Transition pH
color
range
0.0–2.0
blue-violet
High pH
color
Leucomalachite yellow
0.0–2.0
green
(firsttransiti
Leucomalachite green
on)
11.6–14
colorless
Thymol
blue
red
1.2–2.8
yellow
Thymol blue (second
transition)
Methyl yellow
yellow
8.0–9.6
blue
red
2.9–4.0
yellow
Bromophenol blue
yellow
3.0–4.6
purple
Congo red
blue-violet
3.0–5.0
red
Methyl orange
red
3.1–4.4
orange
Bromocresol green
yellow
3.8–5.4
blue-green
Methyl red
red
4.4–6.2
yellow
Methyl red / Bromocresol
green
Azolitmin
red
4.5–5.2
green
red
4.5–8.3
blue
Bromocresol purple
yellow
5.2–6.8
purple
Bromothymol blue
yellow
6.0–7.6
blue
Phenol red
yellow
6.8–8.4
red
Neutral red
red
6.8–8.0
yellow
Naphtholphthalein
7.3–8.7
Cresol Red
colorless to
reddish
yellow
Phenolphthalein
colorless
greenish to
blue
reddishpurple
fuchsia
Thymolphthalein
colorless
Alizarine Yellow R
yellow
7.2–8.8
8.3–
10.0
9.3–
10.5
10.2–
12 0
blue
red