Sifat Anti mikrobial dari
Metabolit Sekunder tanaman
Nur Hidayat
Pendahuluan
• Berbagai organisme hidup dan tumbuh di
dunia
• Ada interaksi antar organisme tersebut
sehingga terjadi hubungan yang saling
menguntungkan ataupun merugikan
• Interaksi tersebut dapat menghasilkan
senyawa baru dan umumnya merupakan
metabolit sekunder
Interaksi tanaman dan
mikroorganisme
• Tanaman dapat berinteraksi dengan berbagai
mikroorganisme dan berbagai bentuk interaksi
• Salah satu bentuk interaksi adalah parastisme yaitu
penyerangan bakteri atau jamur pada tanaman yanng
dapat menyebabkan penyakit pada tanaman (plant –
pahogen interaction)
• Jika cocok maka mikroorganisme akan dapat tumbuh
dan menyebabkan tanaman sakit jika tidak maka mikro
tsb akan mati atau tidak tumbuh.
• Dasar ketahanan tanaman dari patogen ada dua
– specific plant disease resistance
– non-specific plant disease resistance
Specific plant disease resistance (host
resistance)
• Resistensi spesifik terjadia karena adanya
kesesuaian gen – gen dari tanaman dan
penyebab penyakit.
• Tanaman meletakkan beberapa senyawa shg
menghambat pertumbuhan mikroorganisme
• Sbg contoh tanaman lobak menghasilkan 1,3β-glucanase, yang dapat melindungi dari
serangan jamur Phytophthora infestans dan
Non-specific plant disease resistance
(non-host resistance)
• Mikroorganisme menyerang tanaman dan
tidak spesifik.
• Pertahanan tanaman menjadi tidak spesifik
• Ada dua strategi yang diterapkan:
– constitutive defence mechanism
– constitutive defence mechanism
The constitutive defence
mechanism
• Menghasilkan senyawa yg berfungsi melawan
bakteri, jamur dan virus dengan menghasilkan
senyawa-senyawa bererat molekul rendah:
cyanogenic glycosides, mustard oil, glycosides,
alkaloids, phenols, essential oils dan tannin.
• Menggunakan perlindungan fisik seperti
bentuk rambut, paku, duri, kulit keras dan
sebagainya
infection-induced defence mechanism
• Tanaman menghasilkan senyawa, apabila ada
serangan mikroorganisme
• Pada keadaan normal senyawa ini tidak
dihasilkan.
Rapid plant defence response
1. Changes in plasma membrane ion flux (e.g. Ca2+, K+,
H+).
2. Generation of active oxygen species (oxidative burst).
3. Protein phosphorylation cascades.
4. Production of hydroxyproline-rich glycoproteins to
strengthen the cell wall barrier to pathogens.
5. Initiation of phytoalexin synthesis.
6. NO (nitric oxide) accumulation. NO has a key role in
plant pathogen response.
7. Hypersensitive response. Hypersensitive cell death is a
mechanism widely used by hosts to prevent the spread
of pathogens, and in some cases, killing them.
Phytoalexins
• Mikroorganisme yang menyerang tanaman
dapat ditolak tanaman oleh reaksi
hipersensitif tanaman.
• Apabila sel tanaman diserang jamur, maka selsel tanaman disebelahnya akan mati berwarna
coklat (nekrosis)shg jamur tidak tumbuh
menyebar.
• Pada nekrosis sering ditemukan senyawa
antibiotik yg disebut phytoalexin.
Chemical structures and distribution
• Phytoalexins (Greek: phyton, meaning plant;
alexis, meaning defence) are defined as lowmolecular-weight and antibiotically effective
substances of plant secondary metabolism,
the synthesis and accumulation of which is
induced by pathogens or herbivores (M¨ uller
and Borger, 1940).
• The induction of phytoalexin synthesis in plant
tissue has been studied mainly in pathogenic
fungi; however, studies of attacks by viruses,
bacteria, nematodes, arachnida and insects
have also been conducted.
• Correspondingly, antibacterial, fungistatic and
nematostatic phytoalexins have been
discovered, as have those which deter insects
from feeding.
• These substances usually demonstrate a biostatic
or biocidal effect at relatively low concentrations
(0.0001 to 0.00001 M/L).
• At present, we are aware of over 350 different
phytoalexins in more than 100 plant species.
• Their molecular structures reflect the variation in
secondary plant metabolic pathways, since
phytoalexins can be found among the alkaloids,
coumarins, dihydrophenanthrenes, flavonoids,
isoflavonoids, phenols, polyacetylenes, steroids,
stilbenes and terpenes
Specificity of phytoalexin
accumulation
1. ‘Localization and timing of phytoalexin
accumulation in infected tissue in relation to
pathogen development.’
2. ‘Phytoalexins must accumulate to
antimicrobial levels at the infection site in
resistance plants in sufficient concentrations
to inhibit the pathogen at the time pathogen
development is stopped.’
Specificity of phytoalexin
accumulation
3. ‘Strong positive correlation of rapid phytoalexin
production with incompatible interactions in
gene-for-gene plant pathogen systems.’
4. ‘Association of rapid phytoalexin accumulation
with resistance genes that condition restriction of
pathogen development.’
5. ‘Use of metabolic inhibitors that enhance
susceptibility and block phytoalexin production.’
Specificity of phytoalexin
accumulation
6. ‘A positive relationship between pathogen
virulence and tolerance of phytoalexins.’
7. ‘An increase of plant tissue resistance by
stimulation of phytoalexin production prior to
inoculation.’
8. ‘There must be evidence that the
phytoalexins are directly involved in defence,
and that this defence role has a measurable
benefit for the plant.’
Specificity of phytoalexin
accumulation
• In general, the levels of phytoalexin in the plant tissue are
regulated by new synthesis and degradation of secondary
metabolites.
• Phytoalexins are synthesized relative quickly after contact
with the attacking pathogen.
• After a lag phase, at a minimum of 2 h, the bioactive
substance can be measured and the amounts increase
during the following hours and days for up to about 96 h,
sometimes longer, until maximum accumulation has been
achieved.
• Subsequently, the levels of phytoalexin decrease to those
which existed before the attack.
• This means that high levels of phytoalexin accumulation do
not persist in plants once a pathogen or stress has been
contained and plant metabolism has returned to normal
Essential oils with antimicrobial
activity
(1) gram-positive bacteria, e.g. Bacillus cereus, Bacillus subtilis,
Mycobacterium intracellulare, Sarcinia flava, Sarcinia lutea,
Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus
faecalis, Streptococcus hemolyticus and Streptococcus pneumoniae;
(2) gram-negative bacteria, e.g. Enterobacter cloacae, Escherichia coli,
Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus
morgani, Proteus rettgeri, Pseudomonas aeruginosa. Salmonella
enteritidis, Salmonella typhosa, Salmonella typhimurium, Shigella
flexneri and Shigella sonnei;
(3) yeasts, e.g. Candida albicans, Candida kruzei, Candida tropicalis,
Saccharomyces cerevisiae, Schizosaccharomyces pombe, Torula glabrata,
Torulopsis utilis, Torulopsis glabrata and Trichosporon capitatum; and
(4) fungi, e.g. Aspergillus fumigatus, Aspergillus niger, Aspergillus ochraceus,
Epidermophyton flocosum, Fusarium sporotrichoides, Fusarium tricintum,
Microsporum canis, Penicillium rubrum, Penicillium spinulosum,
Trichophyton rubrum and Trichophyton mentagrophytes.
Isolated secondary plant metabolites
with antimicrobial properties
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Alkaloid
Aliphatic aldehydes
Anthraquinones
Diterpenoids
Monoterpenoids
Flavonoids
Alkaloid
Bioactive alkaloids could be found within
acridone-, aporphine-, benzophenanthridine-,
bisbenzylisoquinoline-, indole-, isoquinoline-,
piperidine-, protoberberine-, quinoline-,
terpenoid- and steroid-type alkaloids
Dictamnine, a furoquinoline alkaloid, isolated
from the root bark of Dictamnus dasycarpus (a
traditional Chinese medicine), exhibited strong
antifungal activity against the pathogenic fungus,
Cladosporium cucumerium (minimal
concentration required to cause 50% inhibition
[MIC50 25.0 μg/mL]).
Aliphatic aldehydes
• Olive oil derived from Olea europaea
(Oleaceae) has been used worldwide in
traditional medicine to treat skin diseases.
• Oleuropein and hydroxytyrosol, two
secoiridoids contained in olive oil, are known
for their antibacterial activities.
• It was hypothesized that these phytoagents
act not only on the plasmatic membrane but
also on intracellular targets
Anthraquinones and Diterpenoids
• Anthraquinonic compounds, traditionally used
as laxatives, possess many other
pharmacological properties, including
microbiological action
• Diterpenoids lanigerol and forskalinone,
isolated from the roots of Salvia lanigera and
Salvia forskahlei, respectively, demonstrated
moderate antibacterial activity against grampositive bacteria