ANTIBACTERIAL ACTIVITY OF ISOLATEDPHYTOCHEMICALS(MICRO-591)Maninderjeet kaurL-2008-BS-09-IMM.Sc. Int. (Hons.) MicrobiologyPunjab AgriculturalUniversity,Ludhiana
PHYTOCHEMICALS “Phyto” - plant. Naturally occurring, biologically active chemicalcompounds in plants. Phytochemicals are beneficial to human health asresponsible for the disease protection through variousmodes of action.
More than 4000 of these compounds have beendiscovered to date and it is expected that scientistswill discover many more.
FLAVONOIDS Important group of polyphenols Widely distributed among the plant flora Found in almost all plant based food and beverages Level depending in degree of ripeness, variety andprocessing >4000 distinct flavonoids identified
Nearly present in 70% of plants. Quercetin, Kaempferol and QuercitrinOther group include Flavans Flavonods Anthocyanidins CatechinAnthocyanidins
PHENOLICS Chemical compounds occur as natural colorpigments Responsible for the color of fruits of plants Have multiple functionsClassified into- Phenolic acids Flavonoid polyphenolics (flavones, flavonones) Non-flavonoid polyphenols
CAFFEIC ACID is regarded as most commonphenolic compound distributed in plant flora.
TANNINS Widely distributed in plant flora Phenolic compounds of high molecular weight Found in root, bark, stem and outer layers of planttissues Gallic acid- plant derived
TERPENES Most widespread Chemically diverse group of natural productsMajor plant derived- β- Caryophyllene Terpenolen α- cubebene
MECHANISM OF ACTION OF PHYTOCHEMICALS Inhibit microorganisms Interfere with metabolic processes Modulate gene expression Modulate signal transduction pathways Chemotherapeutic with chemo-prevention referringto the use of agents to inhibit, reverse or retardtumourgensis.
SOME SPECIFIC MODES OF ACTIONS Anti-oxidants Anti-carcinogenic Anti-ulcer Anti-diabetic Anti-inflammatory Antimicrobial activity
ANTIMICROBIAL ACTIVITY Protect against pathogenic insects, bacteria, fungior protozoa. Phenolics helping in the reduction of particularadherence of organisms to the cells lining thebladder which reduces UTIs. Exert bacteriostatic or bactericidal activity onmicrobes.
Volatile gas combinations of cinnamon and clove oilinhibit growth of spoilage fungi, yeast and bacteria. Antimicrobial activity varies for the same plant part testeddue to geographical location, nutrient content andextraction methods.
ANTIBACTERIAL ACTIVITY MECHANISMS OFVARIOUS PHYTOCHEMICALS1.Inhibition of nucleic acid- DNA synthesis strongly inhibited by flavonoids inProteus vulgaris RNA synthesis most affected in Staphylococcusaureus. B-ring intercalates with the hydrogen bonding withthe stacking of nucleic acid bases and lead toinhibitory action. DNA gyrase was inhibited in Escherichia coli. bydifferent phytochemicals.
2. Inhibition of cytoplasmic membrane functionSophoraflavanone G have antibacterial activity againstMethicilin-resistant Staphylococcus aureus andstreptococci.Studied through liposomal model membranes lead to thealteration of membrane fluidity in hydrophilic andhydrophobic regions so reduce the fluidity of outer andinner layers.
A strong antibacterial catechin found in green tea. Catechin have greater activity against Gram-positive thanGram-negative bacteria. Catechin perturb lipid bilayers by directly penetratingthem and disrupting the barrier function.
3. Inhibition of energy metabolism Licochalcone (flavonoids) have inhibitory activity againstStaphylococcus aureus and Micrococcus luteus but notagainst E.coli. Interferes with the energy metabolism as energy isrequired for active uptake of various metabolites. Inhibit strongly oxygen-consumption in Micrococcusluteus and Staphylococcus aureus but not in E.coli.
ANTIBACTERIAL ACTIVITY OF AQUEOUSEXTRACT OF ALLICIN AGAINST METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS Allicin main biologically activeantimicrobial phytochemical produced in garlic extracts The allicin liquid tested forantimicrobial activity against MRSAusing an agar well diffusion method. Determination of minimum inhibitoryconcentration (MIC) and minimumbactericidal concentration (MBC).
A TYPICAL ZONE OF INHIBITIONPRODUCED BY 500MG/ML ALLICINAGAINST MRSA. Allicin liquid was activeagainst S. aureus strainsat or above 62.5 μg/mL. No activity was detectedbelow 62.5 μg/mL Concentrations of 250μg/mL and above aremost active.
88% of strains have MICs for allicin at 16 μg/mL, and allstrains were inhibited by allicin at 32 μg/mL. The present study demonstrated that the majority (88%)of strains have MBCs for allicin at 128 μg/mL and all thestrains were killed by allicin at 256 μg/mL.
PHYTOCHEMICALS OF CITRUS FRUITS Different solvent extracts (ethyl acetate, ethanol,petroleum ether and water) showed the presence offlavonoids, terpenoids, tannins and alkaloids fromcitrus fruit peels and Citrus limon.
ANTIBACTERIAL ACTIVITY Against four pathogenic bacteria organisms (S.aureus, E.coli, S. typhi and K. pneumonia ) Acetone extract of Citrus sinensis shows maximumzone of inhibition against E.coli (16mm) followed byS. typhi (15mm), K. pneumonia (14mm) and S.aureus (13mm) whereas the ethanol and aqueousextract of Citrus sinensis not show such highantibacterial activity.
Not all phytochemicals have equal antibacterial activity.This is due to the difference in extraction process anddifference in plant parts.
PHYTOCHEMICALS OF MENTHA PIPERITAL.(PEPPERMINT) Perennial and stronglyscented herb. Crude extracts fromdifferent plant part is rich inat least one of the alkaloids,flavonoids, phenols,tannins. Higher concentrations ofalkaloids were present inthe ethanol, methanol andethyl acetate leaf extractswhen compared to the stemand root extracts.
The antibacterial potential of six extracts from leaf, stemand root are effective against bacteria such as B. subtilis,S. pneumonia, S. aureus, E. coli, P. vulgaris and K.pneumonia. Among all the extracts, ethyl acetate, chloroform andethanol leaf extracts showed high activity (7.2 - 15.3 mmof zone of inhibition) on all organisms. The root extracts (chloroform, hexane and petroleumether) did not show any activity on S. pneumonia, S.aureus, E. coli, P. vulgaris and K. pneumonia.
PHYTOCHEMICALS OF MEDICINALPLANTS(TULSI, CLOVE, NEEM AND DATIWAN) The percentage yield of thephytochemicals in theseplants are- Tulsi-29.08% Clove-19.58% Datiwan- 21.07% Neem- 17.15%Basically, alkaloids,glycosides, terpenoids,steroids, flavonoids, tanninsand reducing sugars werethere.
Among four plants Clove is most effective against S.typhi. All the plants were ineffective against E. coli and K.pneumonia. The largest zone of inhibition (22 mm) obtained withclove against S. typhi and Minimum BactericidalConcentration (MBC) value of 5 mg/l effective with Neemagainst S. typhi K. pneumoniae and E. coli were found to be resistantwith all the plant extracts.
PHYTOCHEMICALS OF AMLA (EMBLICAOFFICINALIS) Thephytochemicalsfrom the solventfree extract ofEmblica officinalisfruit as well leafare:-
Isolated phytochemicals show antibacterial activityagainst three respiratory pathogens i.e. Staphylococcusaureus, Streptococcus pyogenes, Klebsiellapneumoniae. Synergistic interactions are also important.+++ : Highest synergistic activity ++ : Moderate synergistic activity, - :Indifference
PHYTOCHEMICALS OF SWEITNIAMAHAGONI Large deciduous and economically timber tree. The crude extract of this consists of
The seed extract is active against 5 Gram positive and 9Gram negative bacteria and 5 fungal strains.
The extract is more active as compared to amoxicillinagainst Bacillus thuringienesis and Pseudomonasaeruginosa at 1mg/L. The MIC and MBC ranging form 12.5 to 50 mg/L and 25to 50 mg/L for the SMCM seed extract respectively.
PHYTOCHEMICALS OF MORINGA OLEIFERA Commonly known as “Drumstick”. Highly nutritive vegetable in manycountries. Leaves contains phytochemicalshaving potent anticancer activity.
Antimicrobial activity of Chloroform, Ethanol, Water extract of Moringaoleifera against human pathogens
The antibacterial activity of chloroform extract-Maximum zone of inhibition (6 mm) against Escherichia Coli,Salmonella typhii, No zone of inhibition against Pseudomonasaeruginosa, Staphylococcus aureus. The antibacterial activity of ethanol extractMaximum zone of inhibition (14 mm) against Salmonellatyphii and minimum inhibitory zone (8 mm) againstEscherichia Coli . The antibacterial activity of aqueous extract-Maximum inhibitory zone (8 mm) against Staphylococcusaureus. No inhibitory zone against Salmonella typhii,Pseudomonas aeruginosa, Escherichia Coli.
CONCLUSION Future optimization of these compounds throughstructure alteration allow the development of apharmacologically acceptable antimicrobial agentand group of agents. The increasing acceptance of the chemical diversityof natural products is well suited to provide the corescaffolds for future drugs. There is need to be further developments in the useof novel natural products and chemical librariesbased on natural products in drug discoverycampaigns