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Indian Journal of Pharmacology, Vol. 37, No. 6, November-December, 2005, pp. 408-409 Research Letter Preliminary screening of some folklore medicinal plants from western India for potential antimicrobial activity Jigna P, Rathish N, Sumitra C Phytochemical, Pharmacological and Microbiological Laboratory, Department of Biosciences, Saurashtra University,Rajkot-360 005. Code Number: ph05110 In recent years, multiple drug resistance has developed due to indiscriminate use of existing antimicrobial drugs in the treatment of infectious diseases.[1] In addition to this, antibiotics are sometimes associated with adverse effects on the host-like hypersentivity. Therefore, there is a need to develop alternative antimicrobial drugs for the treatment of infectious diseases from other sources, such as plants.[2] Natural products of higher plants may be a new source of antimicrobial agents possibly with novel mechanisms of action.[3] In vitro antimicrobial activity of aqueous and ethanol extracts of six medicinal plants used by traditional healers was examined. Microorganisms were obtained from National Chemical Laboratory (NCL), Pune, India. Microorganisms were maintained at 4°C on nutrient agar slants (for bacteria) and MGYP slants (for yeast). Plant material (10 g) was extracted with 100 ml ethanol by subjecting it to agitation on rotary shaker (190-200 rpm) overnight, filtering it with muslin cloth and concentrating it to one-fifth of the volume. Crude aqueous extract was prepared by subjecting plant material (10 g) to slow heat for 6 hours and filtered through muslin cloth and concentrated it to one-fifth of the total volume. Antimicrobial activity of the ethanolic extracts was evaluated by agar well diffusion method[4] while aqueous extracts were evaluated by agar disc diffusion method.[5] The sensitivity of the extracts was measured using the diameter of the zone of inhibition. Amongst the 12 extracts obtained from six plants, majority were active against Gram-positive bacteria [Table - 1], of which, the ethanol extracts were more active than aqueous extracts. The aqueous extract of Acyranthus aspera L. could inhibit Staphylococcus epidermidis to a certain extent; while rest of the bacteria was resistant to both aqueous and ethanolic extract of this plant. Aqueous extract of Calotropis gigantea L. could not inhibit any of the bacterial strains investigated except Proteus mirabilis. The ethanolic extract was most active against Klebsiella pneumoniae. Carissa congesta Wt. showed similar trend as that of Calotropis gigantea L. in which aqueous extract showed some activity only against Bacillus cereus, while ethanol extract could show antimicrobial activity to some extent. The ethanolic extract of Fagonia cretica L. and Rauvolfia serpentina L. could inhibit some of the bacterial strains studied to some degree while aqueous extract of both these plants did not show any activity at all. M. indica L. (both extracts) displayed remarkable activity. The most susceptible bacteria were Klebsiella pneumoniae followed by Bacillus cereus, Escherichia coli and Alcaligenes fecalis. Salmonella typhimurium was the most resistant bacteria. All the aqueous extracts were inactive against C. tropicalis and only three ethanolic extracts viz. Calotropis gigantea L., Carissa congesta Wt. and Rauwolfia serpentina L. showed anticandidal activity . These observations are likely to be the result of the differences in cell wall structure between Gram-positive and Gram-negative bacteria, with Gram-negative outer membrane acting as a barrier to many environmental substances, including antibiotics.[6] The results can be compared with the standard antimicrobials [Table - 1]. In conclusion, the results of the present study support the folkloric usage of the studied plants and suggest that some of the plant extracts possess compounds with antimicrobial properties that can be further explored for antimicrobial activity. References
Copyright 2005 - Indian Journal of Pharmacology The following images related to this document are available:Photo images[ph05110t1.jpg] |
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