Phytochemical screening of Aloevera – An Overview
*Mrs. Bele Archana, Dr.Khale Anubha
Pacific University, Udaipur,
H.K College of Pharmacy, Jogeshwari(W), M.S.
ABSTRACT:
Aloe vera is a perennial, drought-resisting, succulent plant belonging to the Asphodelaceae
family which, historically has been used for a variety of medicinal purposes. It has a vast
traditional role in indigenous system of medicine like ayurveda, siddha, unani and
homoeopathy. The present reviews the phytochemical, traditional and pharmacological
properties of various bioactive compounds present in Aloe vera. The plant contains many
medicinally active phytoconstituents. The present review is therefore, an effort to give a
detailed survey of the literature on its traditional, and phytochemical properties.
Keywords: phytochemical, traditional, pharmacological, bioactive compounds, Aloe vera.
* Correspondence:
Mrs.Archana. A. Bele
Lecturer
H.K.College of Pharmacy,
Jogeshwari(W)
e-mail: archana.bele@hkcollege.ac.in, archana.bele@gmail.com
anubha.khale@hkcollege.ac.in
INTRODUCTION
Medicinal plants are very ancient and only true natural medicines useful in several ways for
the treatment of different diseases. They can be used directly or in extracted forms for the
management of various ailments due to presence of various phytochemicals. For the
prevention and treatment of various health ailments, plants and isolated phytochemicals have
been used from decades. A large number of phyto drugs prescribed worldwide are
derived directly or indirectly from natural sources. A large number of African and Asian
populations use traditional medicines for their primary healthcare. About 2-3 decades ago
most of the drugs were of herbal origin. A variety of reasons strengthen why people like to
use natural medicines such as fewer side effects on human health and cost effectiveness.
Herbal medications gain popularity due to a perception that there is a lower incidence of
adverse reaction to plant preparation compound to synthetic pharmaceuticals.
The Aloe vera plant has been known and used for centuries for its health, beauty, medicinal
and skin care properties. The name Aloe vera is derived from the Arabic word “Alloeh”
meaning “shining bitter substance,” while “vera” in Latin means “true.” 2000 years ago, the
Greek scientists regarded Aloe vera as the universal panacea. The botanical name of Aloe
vera is Aloe barbadensis miller. It belongs to Asphodelaceae. It is grown in most subtropical
and tropical locations, including South Africa, Latin America, and the Caribbean. Aloe was
one of the most frequently prescribed medicines throughout most of the 18th and 19th
centuries and it remains one of the most commonly used herbs in the United States today. 12
Aloe vera is a perennial, succulent plant (meaning its leaves hold large quantities of water).
The plant can grow up to 4 feet tall, and it’s tough, fleshy, spear like leaves can grow up to 36
inches long. The clear, thick gel found in the inner part of the leaf is most commonly used for
minor cuts and burns.
Aloe vera is as old as civilization and throughout history it has been used as a popular folk
medicine. It is present in the arid regions of India and is believed to be effective in treating
stomach ailments, gastrointestinal problems, skin diseases, constipation for radiation injury,
for its anti-inflammatory effect, for wound healing and burns, as an anti-ulcer and diabetes5
It is a plant related to cactus. It produces two substances, gel and latex, which are used for
medicines. Aloe gel is the clear, jelly-like substance found in the inner part of the aloe plant
leaf. Aloe latex comes from just under the plant's skin and is yellow in color. Aloe vera
contains 99.3 percent water and 0.7 percent nonaqueous constituents, such as glycoproteins
and polysaccharides etc. Glycoproteins speed the healing process by stopping pain and
inflammation, while polysaccharides stimulate skin growth and repair. These substances may
also stimulate the immune system2, 13, 14
The genus Aloe contains over 400 different species with Aloe barbadensis Miller (A. vera),
Aloe aborescens and, Aloe chinensis being the most popular. Aloe barbadensis Miller is
considered to be the most biologically active.
The earliest recorded pharmacological usage was recorded in ancient Sumeria about 1750
B.C. A. vera has been used throughout history in folk medicine as valuable ingredient
for the food, pharmaceutical and cosmetic industries. Adulteration represents a major concern
for the A. vera market, mostly because of the high cost of the raw materials. Historically, the
most common substance used to adulterate aloe gel powder is maltodextrin. Development of
various novel analytical techniques for the analysis of medicinally active phytoconstituents in
the herbal has become an important step of herbal drug standardization. The overall objective
is to review qualitative and quantitative technique, which can help in the quantification of
different constituents of A. vera herbal extract. 9, 10,15
Phytochemical composition of Aloe vera :
The plant contains flavonoids, terpenoids, lectins, fattyacids, cholesterol, anthraquinones,
Chromones (8-C-glucosyl-7-O-methylaloediol, 8-C-glucosyl-noreugenin, Isoaloeresin D,
iso rabaichromone, neoaloesin A, mono and polysaccharides (pectins, hemicelluloses,
glucomannan, acemannan, and mannose derivative), tannins, sterols (lupeol, campesterol, and
βsitosterol), salicylic acid, organic acids, enzymes, saponins, vitamins, minerals, aloin,
anthrone, aloe emodin (3- hydroxylmethyl-chrysazin), aloetinic acid, choline and
choline salicylate, complex mucopolysaccharides similar to hyaluronic acid, sapogenins and
enzymes such as catalase, amylase, cellulase and alliinase. Minerals such as calcium,
magnesium, potassium, sodium, aluminum, iron and zinc. Aminoacids such as arginine,
asparagine, glutamic acid, aspartic acid and serine. Vitamins such as B1, B2, B6, C, βcarotene, choline, folic acid, α-tocopherol are present. Free monosaccharides consisted of
D-mannose and D-glucose in a molar ratio of 5:4 and trace amounts of xylose, rhamnose,
galactose, and either arabinose or fructose were found. Mannose 6 phosphate is a major sugar
component in Aloe vera.
Determination of phytochemical constituents in Aloe vera
The freshly prepared extracts are subjected to standard phytochemical analysis for different
constituents such as tannins, alkaloids, flavonoids, anthraquinones, glycosides, saponins,
terpenoids and reducing sugars5
Phytochemical methods
Preliminary phytochemical screening for alkaloids, steroids, carbohydrates, tannins, fixed
oils, proteins, triterpenoids, deoxysugar, flavonoid and glycosides are carried out according to
the official procedures to know the presence of different phytoconstituents in the A. vera
extract. Thin layer chromatography (TLC) profile of the A. vera extract are carried out to
confirm the presence of different phytoconstituents. In TLC, spots are developed
in the different solvent system of varying polarity. Further developed spots are identified by
different spraying reagents. Solubility, loss on drying, heavy metal and microbiological
analysis are also performed. Total phenol and flavonoid content are also determined in the
A. vera extract according to the standard procedure11. Aluminum chloride colorimetric
method can be used for the total flavonoid determination using rutin as a standard. Gallic acid
can be used for the determination of total phenol content. Different combination of solvent
system of varying polarity can be used for the optimization of solvent system in high
performance thin layer chromatography (HPTLC) methods. Gallic acid and berberine are
used as a standard marker compound at different concentration. Heavy metal analysis is done
to detect the presence of lead, arsenic, mercury and cadmium 3
Analytical techniques for evaluation of medicinally active phytoconstituents on qualitative
and quantitative basis, is very important in herbal drug standardization.5
Preliminary Phytochemical Screening of Aloe Vera
Various qualitative methods are employed to standardize Aloe vera. Phytochemical tests are
carried out to confirm the presence of chemical constituents.Quantitative determination can
be done by Chromatographic method like HPLC, HPTLC etc and Spectroscopy methods.
Procedures for Preliminary Phytochemical Test are4
Test for tannins
Stir about 2ml of the aqueous extract with 2ml of distilled water and add few drops of FeCl3 solution
(5%w/v). The formation of a green precipitate indicate the presence of tannins.
Test for phlobatannins
Take 2ml of aqueous extract add to 2ml of 1%HCl and the mixture is boiled. Deposition of a red
precipitate is taken as an evidence for the presence of phlobatannins.
Test for flavonoids
Take 1ml of aqueous extract, add 1ml of 10% lead acetate solution . There is formation of a yellow
precipitate which indicates a positive test for flavonoids.
Tests for anthraquinones
(a) Borntrager’s test: Take 3ml of aqueous extract and shake with 3 ml of benzene, filter and add 5 ml
of 10% ammonia solution . The mixture is shaken and the presence of a pink, red or violet colour in
the ammonical (lower) phase indicates the presence of free anthraquinones.
(b) Take 3 ml of the aqueous extract and boil it with 3ml of aqueous sulphuric acid and filter while
hot. 3 ml of benzene was added to the filtered and shaken. The benzene layer was separated and 3 ml
of 10% HNO3 added. A pink, red or violet colouration in the ammonical (lower) phase indicates the
presence of anthraquinone derivatives.
Test for terpenoids
Take 2ml of the organic extract was dissolved in 2 ml of chloroform and evaporate to dryness. 2 ml of
concentrated sulphuric acid is then added and heated for about 2 min. A greyish colour indicates the
presence of terpenoids
Tests for steroids
(i) A red colour produced in the lower chloroform layer when 2 ml of the extract is dissolved in 2 ml
of chloroform and add 2 ml concentrate sulphuric acid added in test tube indicates the presence of
steroids.
(ii) The development of a greenish colour when 2 ml of the organic extract was dissolved in 2 ml of
chloroform and treated with sulphuric and acetic acids indicates the presence of steroids.
Test for alkaloids
Take 3ml of aqueous extract and stir with 3 ml of 1% HCl on a steam bath. Mayer’s and Wagner’s
reagents is then added to the mixture. Turbidity of the resulting precipitate is taken as evidence for the
presence of alkaloids.
Tests for carbohydrates
(a) Molisch’s test: Take 3 ml of the aqueous extract was added to 2 ml of Molisch’s reagent and the
resulting mixture shaken properly, then 2 ml of concentrated H2SO4 was poured carefully down the
side of the test tube. A violet ring at the interphone indicates the presence of carbohydrate.
(b) Take 3 ml of the aqueous extract into test tube and add 1 ml of iodine solution . A purple
coloration at the interphone indicates the presence of carbohydrates.
Tests for Glycosides
(a) Liebermann’s test
Take 2 ml of the organic extract and dissolve in 2 ml of chloroform, add 2 ml of acetic acid carefully.
A color change from violet to blue to green indicates the presence of a steroidal nucleus (i.e. aglycone
portion of glycoside.
(b) Salkowski’s test
Take 2 ml of extract and dissolve in 2 ml of chloroform add 2 ml of sulphuric acid and shake gently.
A reddish brown colour indicates the presence of a steroidal ring (i.e., a glycone portion of glycoside)
Test for amino acids:
Ninhydrin’s test: Ninhydrin a powerful oxidizing agent reacts with all alpha amino acids
between pH 4 and 8 to give a purple coloured compound. Take 1 ml of test solution in test
tube and adjust the pH to about neutrality. Add 5 drops of ninhydrin solution and boil for 2
minutes.
Test for presence of calcium:
Take 5 ml of 5 M acetic acid to 5 ml of aloe vera juice. Add potassium ferrocyanide solution.
The solution remains clear. Add about 50 mg of ammonium chloride a white crystalline
precipitate is formed.
Test for presence of magnesium:
Take about 5 ml of juice add 1 ml of dilute ammonia solution. A white precipitate forms that
is redissolved by adding 1 ml of 2M ammonium chloride. To the solution 1 ml of 0.25 M
disodium hydrogen phosphate is added. A white crystalline precipitate is formed.
Determination of total carbohydrates content in terms of glucose by phenol
sulphuric assay method
Phenol - Sulphuric Acid Method is the most easiest and reliable method amongst the
quantitative assays for carbohydrate estimation. In hot acidic medium, glucose is dehydrated
to hydroxymethyl furfural. This forms a yellow-brown coloured product with phenol and has
absorption maximum at 490 nm. This is one of the best methods to estimate total
carbohydrates. The Phenol Sulphuric Acid method is carried out by preparing a set of
solutions with known glucose concentrations and mixing them with the Phenol- Sulphuric
acid reagent. A standard curve can be made and the concentrations of unknown sugar
samples can be derived from the standard curve.
Screening by antimicrobial activity
Bacterial Cultures
Bacterial species like Staphylococcus, aureus, Staphylococcus epidermis, Escherichia
coli and Bacillus subtilis are inoculated in nutrient broth and allowed to grow overnight at
370C. This freshly grown culture is used for analysis.
Antibacterial Activity by Disc Method
The paper Disc plate method is the most commonly used technique for determining
susceptibility of micro organisms to know concentration of antibiotics. Small paper Disc
impregnated with combination extraction agents are placed upon the surface of pre inoculated
plate .The plates are incubated at 37 0C for 24 hours. Susceptibility of effectiveness is
observed by the diameter of the inhibition zone around the Disc. Organisms which grow up to
the edge of the disc are resistant.
Antibacterial Activity by Streak Plate Method
Petri plate containing Nutrient Agar is seeded with the combination mixture and allowed to
solidify. Overnight grown cultures are than taken one by one and streaked on the plate. A
control plate continuing only nutrient agar devoid of antibiotic mixture is simultaneously
streaked and incubated. The growth is observed against the control plate.7
Antifungal Activity of Aloe Vera
The antifungal activity studies are carried out by disc diffusion technique. The sterile nutrient
agar plates and potato dextrose agar plates are prepared. The fungal test organism like
Aspergillus Niger, Aspergillus fumigates and Neurospora crassa are spread over the potato
dextrose agar plates after the microbial lawn preparation three different extracts of plant disc
are placed on the organism inoculated plates with equal distance control discs are also
prepared. All fungal plates are incubated at 24°C for 72hrs. The diameter of the minimum
zone of inhibition is measured in mm. For each test, three replicates are performed. 6
Test to detect the presence of adulterant:
1. Quantitative Proton-Nuclear Magnetic Resonance Spectrometry (1H NMR): For the
determination of Acetylated Polysaccharides, Glucose, and Maltodextrin in Aloe Vera gel
NMR study is to be carried out. 1
2. Kinetics of Nonenzymatic Browning Reaction in Citrus Juice Concentrates during
Storage8:
Browning is the most common quality problem of many concentrated juices and causes loss
of nutrients and the formation of intermediate undesirable compounds and therefore the study
needs to be carried out.
Method: Browning development was determined using color measurement method.
Determination of water soluble brown pigments: Nonenzymatic browning was monitored
using the method UV-VIS spectrophotometer in 10 mm cells against water at 420 nm.
Conclusion:
Phytoconstituents such as alkaloids, flavonoids, tannins, phenols, saponins, and several other
aromatic compounds in the plants serve a defence mechanism by many microorganisms,
insects and other herbivores. Quality evaluation of herbal drug/preparation is a fundamental
requirement of industry and other organization dealing with ayurvedic and herbal products.
The growing use of botanicals needs to develop standards of quality for manufacture.
According to WHO guidelines, a herbal product needs to be standardized with respect to
safety before releasing it into the market.
The drug has many curative properties. Tannins are known to be useful in the treatment of
inflamed or ulcerated tissues, cancer, and mild anti-septics. Flavonoids are considered as
potential antioxidants and have protective action against allergies, inflammation, free radical,
platelet aggregation, microbes, ulcers, hepatoxins, viruses and tumor. Saponins show
potential anti-inflammatory, coagulant, antidiabetic, antioxidant, aldose reductase inhibitory
activity and cholesterol binding properties. The presence of different phytoconstituents can be
confirmed in the Aloe vera gel by performing various test. Different constituents are
confirmed like anthraquinone glycoside, flavonoids, phenolic groups, carbohydrates and
steroids. The presence of the phytoconstituents are further authenticated by the HPLC, NMR,
HPTLC and other spectroscopic techniques.
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