Antimicrobial efficacies of methanol extract of Asteracantha longifolia, Ipomoea aquatica and Enhydra fluctuans against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Micrococcus luteus
J Bhakta, P Majumdar, Y Munekage
antimicrobial activity, medicinal herbs, methanol extract
J Bhakta, P Majumdar, Y Munekage. Antimicrobial efficacies of methanol extract of Asteracantha longifolia, Ipomoea aquatica and Enhydra fluctuans against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Micrococcus luteus. The Internet Journal of Alternative Medicine. 2008 Volume 7 Number 2.
Present experiment was executed to investigate the antimicrobial efficacy of
Herb is an immeasurable wealth of nature not only from the global environmental perspective but also from the medicinal point of view. It plays a significant role ameliorating the disease resistant ability and combating against various unfavourable metabolic activities within the living system. Numerous infectious diseases have been known to be controlled by herbal remedies that have been proved variously since primitive to present history of the mankind. Since time immemorial, man has used various parts of plants in treatment and prevention of various ailments ( 1 ). Unimaginably unrevealed and unmatched varieties of compounds are present in the diversified herbs on earth. From these points of view, it is obvious that natural products, either in the form of pure compounds or as standardized plant extracts, provide unlimited opportunities to develop a variety of new drugs.
Antibiotic resistance has become a global concern ( 2 ). The clinical efficacy of many existing antibiotics is being threatened by the emergence of multidrug-resistant pathogens ( 3 ). There is a continuous and urgent need to discover new antimicrobial compounds with diverse chemical structures and novel mechanisms of action for new and re-emerging infectious diseases ( 4 ). Therefore, researchers are increasingly turning their attention to folk medicine, looking for new leads to develop better drugs against microbial infections ( 5 ). The increasing failure of chemotherapeutics and antibiotic resistance exhibited by pathogenic microbial infectious agents has led to the screening of several medicinal plants for their potential antimicrobial activity ( 67 ). Recent, studies have suggested that several plants species exhibit promising antimicrobial effects ( 8 ). Plant-based antimicrobials have enormous therapeutic potential as they can serve the purpose with lesser side effects that are often associated with synthetic antimicrobials ( 7 ). In recent years, it has been proposed that the herbal extracts may be used as natural antifungal agents to inhibit the growth of foodbrone pathogen
From the above understanding, the present study has been focused on three wild herbs,
However, from the above account, it is obvious that there is no information available about the antimicrobial activity of these herbs. The present investigation was designated to explore the antibacterial activity of methanol extract of the above mentioned herbs.
Materials and methods
Collection and identification of plant materials
Fresh leaf materials of
Preparation of plant extract
The shade and air-dried plant material was ground into fine powder (less than 20 mesh) using a stainless-steel grinder machine and stored in pill vials at room temperature (30°C). An aliquot (2 g) of the powdered plant material was extracted with 60 ml (20 ml x 3 times) 80% methanol for 24 h. After centrifugation at 3800
On the basis of pathogenic importance, four pathogenic bacterial strains (
Preparation of bacterial culture
Aseptically, a single colony was transferred to a 100 ml sterilized nutrient broth by a loop, cotton plugged and placed in incubator overnight at 37 °C. After 12 to 18 h of incubation, the cultures were diluted with sterile normal saline to bring the final inoculum size approximately 10 5 to 10 6 cfu/ml ( 913 ). One ml of the standard bacterial culture was used as inoculation in a nutrient agar petri dish.
Antimicrobial activity assay
One milliliter of cultured bacteria was inoculated on agar plate for preparation of loan of bacteria used for the test of antimicrobial activity following standard methods of agar-cup-diffusion assay. Serial two-fold dilutions (7.5 – 60 mg/ml) of the plant extract were prepared and dispense in each cup (5 mm diameter) of the bacterium seeded/inoculated agar plate @ 30µl/cup. EtOH was used in dissolving the extract; therefore, it is used as control in the assay. Each inoculums and control were employed in triplicate and were incubated at 37 °C for 24 h. antimicrobial activity was assessed based on measurement of the diameter (mm) of the clear zone around the cup.
The triplicate data were expressed as mean ± S.E.M. The results are subjected to an analysis of variance (ANOVA) using the SPSS 10.05 statistical package. If the main effects were disclosed significant at a probability level of P
Antimicrobial activity of
In vitro, agar well diffusion assay of extract activity against four bacterial strains pronounced a significant species dependant response (P < 0.05, ANOVA). No clear zone of the extract was observed in
Antimicrobial activity of
A remarkable and significant antimicrobial activity of
Antimicrobial activity of
There was also a clear variation of antimicrobial activity of
Agar well diffusion assay of extract activity showed a variable clear zones, 0 to 10.7 mm, 0 to 10 mm and 0 to 8 mm in different extract concentrations of
The mean values of the clear zone in
Though no clear zone was found in the methanol extract of the
On account of the above critical appraisal of data, therefore, it could be concluded that (i)
Authors are grateful to Prof. P. K. Bandyopadhyay for providing his laboratory facility and also thankful to Prof. A. Kaviraj, Head, Department.of Zoology for his kind support in the experiment. We are also thankful to Professors of the Department of Botany for extending his cooperation in identification of the herbs.