Journal of Ethnopharmacology 74 (2001) 113 – 123 Antimicrobial and phytochemical studies on 45 Indian medicinal plants against multi-drug resistant human pathogens Iqbal Ahmad *, Arina Z. Beg Department of Agricultural Microbiology, RAK Institute of Agricultural Sciences, Aligarh Muslim Uniersity, Aligarh 202002, India Received 8 February 2000; received in revised form 10 August 2000; accepted 15 August 2000 Abstract Ethanolic extracts of 45 Indian medicinal plants traditionally used in medicine were studied for their antimicrobial activity against certain drug-resistant bacteria and a yeast Candida albicans of clinical origin. Of these, 40 plant extracts showed varied levels of antimicrobial activity against one or more test bacteria. Anticandidal activity was detected in 24 plant extracts. Overall, broad-spectrum antimicrobial activity was observed in 12 plants (L. inermis, Eucalyptus sp., H. antidysentrica, H. indicus, C. equistifolia. T. belerica, T. chebula, E. officinalis, C. sinensis, S. aromaticum and P. granatum). No correlation was observed between susceptibility of test strains with plant extracts and antibiotic resistance behaviour of the microbial strains (Staphylococcus aureus, Salmonella paratyphi, Shigella dysenteriae, Escherichia coli, Bacillus subtilis, Candida albicans ). Qualitative phytochemical tests, thin layer chro- matography and TLC-bioautography of certain active extracts demonstrated the presence of common phytocom- pounds in the plant extracts including phenols, tannins and flavonoids as major active constituents. © 2001 Published by Elsevier Science Ireland Ltd. Keywords: Medicinal plants; Antimicrobial activity; Multidrug resistance; TLC-bioautography www.elsevier.com/locate/jethpharm 1. 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; Dia- mond, 1993). In the present scenario of emergence of multiple drug resistance to human pathogenic organisms, this has necessitated a search for new * Corresponding author. 0378-8741/01/$ - see front matter © 2001 Published by Elsevier Science Ireland Ltd. PII:S0378-8741(00)00335-4