Antimicrobial and phytochemical studies on 45 Indian medicinal plants against multi-drug resistant human pathogens
Introduction
Infectious diseases are the world's leading cause of premature deaths, killing almost 50 000 people every day. In recent years, drug resistance to human pathogenic bacteria has been commonly reported from all over the world (Piddock and Wise, 1989, Singh et al., 1992, Mulligen et al., 1993, Davis, 1994, Robin et al., 1998). However, the situation is alarming in developing as well as developed countries due to indiscriminate use of antibiotics. The drug-resistant bacteria and fungal pathogens have further complicated the treatment of infectious diseases in immunocompromised, AIDS and cancer patients (Rinaldi, 1991, Diamond, 1993). In the present scenario of emergence of multiple drug resistance to human pathogenic organisms, this has necessitated a search for new antimicrobial substances from other sources including plants.
Traditionally used medicinal plants produce a variety of compounds of known therapeutic properties (Iyengar, 1985, Chopra et al., 1992, Harborne and Baxter, 1995). The substances that can either inhibit the growth of pathogens or kill them and have no or least toxicity to host cells are considered candidates for developing new antimicrobial drugs. In recent years, antimicrobial properties of medicinal plants are being increasingly reported from different parts of the world (Grosvenor et al., 1995, Ratnakar and Murthy, 1995, Silva et al., 1996, David, 1997, Saxena, 1997, Nimri et al., 1999, Saxena and Sharma, 1999). It is expected that plant extracts showing target sites other than those used by antibiotics will be active against drug-resistant microbial pathogens. However, very little information is available on such activity of medicinal plants (Hasegawa et al., 1995, Lee et al., 1998). In the present study, we have selected 45 Indian medicinal plants to be screened against multi-drug resistant bacteria including Staphylococcus aureus, Salmonella paratyphi, Escherichia coli, Shigella dysenteriae and Candida albicans. The selection of medicinal plants is based on their traditional uses (32 plants) in India and our reported antimicrobial activity of 13 plants (Chopra et al., 1992, Ahmad et al., 1998, Mehmood et al., 1999). However most of these plants were not previously screened against multi-drug resistant, pathogenic organisms. Phytochemical analysis of active plant extracts for their major group of phytoconstituents and the active group of certain extracts is also reported here.
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Plant material
Thirty-five authenticated plant samples were collected locally and 10 plant samples were kindly provided by the Himalaya Drug Co. (New Delhi, India). All the plant materials were further identified in the Department of Botany, AMU, Aligarh, India by a senior plant taxonomist, Professor Wazahat Hussain. Voucher specimens have been deposited in the Department of Agricultural Microbiology, RAK Institute of Agricultural Sciences, AMU, Aligarh, India. The details of medicinal plants along with their
Results and discussion
Emergence of multi-drug resistance in human and animal pathogenic bacteria as well as undesirable side effects of certain antibiotics has triggered immense interest in the search for new antimicrobial drugs of plant origin. In the present study alcoholic extracts of 45 traditionally used Indian medicinal plants have been tested against drug-resistant bacteria and a pathogenic yeast, C. albicans. Ethnobotanical and phytochemical data, plant parts used along with their acquisition code number are
Acknowledgements
The authors wish to thank the Director of the RAK Institute of Agricultural Sciences, Aligarh Muslim University Aligarh, India for providing facilities for this work. We also thank Dr S. Farooq (Director, The Himalaya Drug Co., New Delhi) for providing some of the plant samples used in this study and Shaba Ansari and Fazlur-Rahman (A. M. U., Aligarh) for their technical help.
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