Antimicrobial activity of certain Indian medicinal plants used in folkloric medicine

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Abstract

Fifty medicinal plants belonging to 26 families were studied for their antimicrobial activity. Among 50 plants tested, 72% showed antimicrobial activity. About 22 plant extracts from 15 families exhibited activity against both Gram-positive and Gram-negative bacteria. Fourteen plants belonging to 11 families did not show activity against any of the bacteria tested. Only nine plant extracts showed antifungal activity. The bulb extracts of A. cepa and A. sativum exhibited activity against both filamentous and non-filamentous fungus. Eight plant extracts belonging to seven families exhibited both antibacterial and antifungal activity.

Introduction

In India, medicinal plants are widely used by all sections of people either directly as folk remedies or in different indigenous systems of medicine or indirectly in the pharmaceutical preparations of modern medicines. According to National Health Experts, 2000 different plants are used for medicinal preparations for both internal and external use in India alone. Among them only 200 are of animal origin, and 300 of mineral origin, while 1500 drugs are extracted from various plants.

A survey by UNCTAD has shown that 33% of total drugs produced by the industrialized nations are plant derived and microbes are considered, 60% of medicinal products are of natural origin (UNCTAD/Gatt, 1974).

Rigveda mentions 67 plants having therapeutic effects, Yajurveda lists 81 plants and Atharveda 290 plants (Nabachandra and Manjula, 1992). The world health organization recently compiled an inventory of more than 20 000 species of medicinal plants. Indian medicinal plants and their products are used to control diverse disease such as catarrh, bronchitis, pneumonia, ulcers and diarrhoea. Researchers are increasingly turning their attention to folk medicine looking for new leads to develop better drugs against cancer, as well as viral and microbial infections (Galal et al., 1991, Hoffmann et al., 1993). Although hundreds of plant species have been tested for antimicrobial properties, the vast majority have not yet been adequately evaluated (Balandrin et al., 1985).

In every developing country it is necessary that the documentation of medicinal plants be treated as a matter of extreme urgency. The present paper deals with the screening of Indian medicinal plants for antimicrobial activity. The pathogenic organisms were selected for the study on the basis of their clinical, pharmaceutical importance as well as for their potential to cause contamination of food and drugs.

Section snippets

Plant collection

Plant materials were collected in fresh condition from the Maruthamalai Hills of Western Ghats, and identified after critical examination, and the plants were deposited in the Herbarium of the Department of Botany, Bharathiar University, Coimbatore.

Preparation of crude extract

Fresh matured leaves, flowers and bulb (25 g) were collected and washed with distilled water. Samples were cut into small pieces and crushed in a mechanical mortar with 25 ml of sterilized distilled water. The extract was filtered off and transferred

Results

The crude extracts of 50 medicinal plants belonging to 26 families were screened for their antimicrobial activity against ten bacterial pathogens and four fungal strains. Among 50 plants tested, 72% showed antimicrobial activity. About 54% of plants showed antibacterial activity, while 2% and 16% exhibited antifungal and combined antibacterial and antifungal activity respectively.

Discussion and conclusions

In the present study, extracts of 50 plants were tested for antimicrobial activity against 14 microbial pathogens. Among them are included Staphylococcus aureus, a pyrogenic bacterium known to play a significant role in invasive skin diseases including superficial and deep follicular lesions Salmonella spp. which infect a number of animal species (Furowicz and Terzolo, 1975) and Salmonella typhi, which causes typhoid fever to human beings. Among fungal pathogens Candida albicans was also chosen

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