Ethnobotanical Leaflets 12: 1213-17. 2008.
Investigations on Antibacterial Activity
of Leaf Extracts of Azadirachta indica
Juss (Meliaceae): A Traditional
Medicinal Plant of
of Biotechnology, Chemical and Biomedical Engineering,
of Humanities and Social Sciences,
Department of Botany, RD
����������� The present study was carried out to screen and evaluate antimicrobial activity of leaf extracts of Azadirachta indica A. Juss. Petroleum ether, dichloromethane, chloroform, ethanol and aqueous extract of leaves of A. indica were tested against selected Gram positive and Gram negative bacterial species. Phytochemical leaf extracts of A. indica exhibited significant anti-bacterial activity against all the test microorganisms. However, inhibitory activities of the leaf extracts were both organism and solvent dependent. The leaf extracts limited the growth of both Gram-positive and Gram-negative bacterial species tested. Among the different extracted used in the study, ethanolic and dichloromethane leaf extracts of A. indica were found to be more active towards the bacterial species used in the study. Further, the aqueous leaf extract was moderately active. However, petroleum ether and chloroform extracts were not effective against any of the organisms tested, but for Bacillus cereus where the chloroform extract was moderately active. Growth of Lactobacillus bulgaris was not inhibited by any of the tested leaf extracts of A. indica but for dichloromethane. The study shows that ethanolic and dichloromethane leaf extracts of A. indica can be used as a potential source of antimicrobial agents.
KEYWORDS: Azadirachta indica; Medicinal Plants; Antibacterial Agents; phytochemicals; Disc Diffusion Assay (DDA).
plants are part and parcel of humans since the dawn of civilization. In
����������� WHO (2005), pointed out that more than 80% of world�s population rely on plants based products to meet their primary health care needs. Overexploitation of selected medicinal plant species has led to significant reduction in number of plants in the wild. Ruthless hunting has resulted in inclusion of their name in the red data book (Ahmedullah and Nayar 1999). In recent years, multiple drug resistance in both human and plant pathogens has been developed due to indiscriminate use of synthetic drugs. This drives the need to screen medicinal plants for novel bioactive compounds as plant based drugs are biodegradable, safe and have fewer side effects (Prusti et al., 2008).
����������� Neem (Azadirachta indica A. Juss) is perhaps
the most commonly used traditional medicinal plant of
����������� Azadirachta indica A. Juss (syn. Melia azadirachta)
is well known in
Collection of Plant Material
leaves of A. indica were
Preparation of Phytochemical Extracts
powder was extracted by maceration in different solvents used in the study
using the cold percolation method. The plant extracts were concentrated using
rotary evaporator (
����������� Eight strains of Gram-positive bacteria - Micrococcus glutamicus, Lactobacillus bulgaris, Streptococcus faecalis, Staphylococcus aureus, Bacillus stearothermophilus, Staphylococcus pyogenes, Micrococcus luteus, Bacillus cereus and two strains of Gram negative bacteria - Escherichia coli and Pseudomonas aeruginosa were used to evaluate the antibacterial activity (Table 1). All bacterial cultures were maintained in NA slants/ plates; stored at 4 and periodically sub-cultured.
Antimicrobial Activity Test
activity was tested using a modified disc diffusion assay (DDA) method
originally described by Bauer (1966) and Ncube et al
(2008).� Plant extracts were dissolved
in 20% DMSO treated water. The inoculums for each microorganism were prepared
from broth cultures (105 CFU/ml). A loop of culture from the NA
slant stock was cultured in LB medium overnight and spread with a sterile
swab into Petri-plates. Sterile disc (6 mm dia,
����������� Plants are known to have beneficial therapeutic effects documented in Traditional Indian System of Medicine. Though bioactive products of Neem have been used in treatment of various aliments since time immemorial, role of phytochemical in inhibition of growth of microorganisms has gained less prominence (Sasidharan et al., 1998; SaiRam et al., 2000). In the present study, petroleum ether, dichloromethane, chloroform, ethanol and aqueous extract of leaves of A. indica were tested against selected Gram positive and Gram negative bacterial species (Table 1). The leaf extracts limited the growth of both Gram-positive and Gram-negative bacterial species tested. Different phytochemical leaf extracts of A. indica exhibited significant anti-bacterial activity against all test organisms. Further, inhibitory role of the leaf extracts was both organism and solvent dependent. Among the different extracted, ethanolic and dichloromethane leaf extracts of A. indica were found to be more active towards the bacterial species used in the study. Aqueous leaf extract of A. indica was moderately active against all the bacterial species tested except M. glutamicus, L. bulgaris and S. pyogenes.
����������� Dichloromethane leaf extract of A. indica exhibited maximum inhibitory activity followed by ethanolic and aqueous extracts against various organisms tested (Table 2). Chloroform extract showed inhibition against only B. cereus. Petroleum ether extract was not effective against any of the organism tested. Among the different microorganisms tested maximum inhibition was found in M. glutamicus followed by S. aureus, B. stearothermophilus, B. cereus and S. faecalis.
though much work has been done on ethnomedicinal plants in
����������� Neem, the versatile traditional medicinal plant of
����������� The authors are thankful to VIT Management for their constant support and encouragements. Thanks are due to Prof. Lazar Mathew for his valuable comments and suggestions to carry out this research successfully.
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Table 1. Bacterial strains used in the present study.
Table 2. Anti-microbial activity of Azadirachta indica leaf extracts.