Extraction and Pharmacological Evaluation of Some Extracts of Tridax procumbens and Capparis decidua

Summary: Free and bound flavonoids of different parts of Tridax procumbens L. (Asteraceae) and Capparis decidua Forsk (Edgew) (Capparaceae) have been studied for their antimicrobial activities using disc diffusion assay, against two Gram negative bacteria (Escherichia coli MTCC 46 and Proteus mirabilis MTCC 425), one Gram positive bacteria (Staphylococcus aureus MTCC 87), and a fungi (Candida albicans MTCC 183). Minimum inhibitory concentration (MIC) of the extracts was evaluated by micro broth dilution method, while minimum bactericidal/ fungicidal concentration determined by subculturing the relevant samples. Both plants exhibited broad spectrum antimicrobial activity. Free and bound flavonoids of T. procumbens flowers and C. decidua stem were found to be more potent. C. albicans was found to be most susceptible organism followed by S. aureus, P. mirabilis, and E. coli. Among 14 extracts tested, 12 were found to be active, while 2 extracts showed no activity at tested concentration. Total activity (TA) was calculated for the extracts, to relate MIC of the extracts with its amount isolated from 1 g dried plant part. Results of the present study indicate that T. procumbens and C. decidua can be exploited for future antimicrobial drugs. Industrial relevance: Adverse effects of popular antibiotics and multidrug resistant strains of pathogens have lead rapid search for new antimicrobials. Because of the long history of plants in the treatment of different human ailments, most of the herbal drugs are believed to be safer than the synthetic drugs with no side effects; therefore medicinal plants have gained more importance as possible source of alternative and effective drugs. Plants and natural products remain as an untapped reservoir of potentially useful chemical compounds not only as drugs but also as unique templates that could serve as a starting point for synthetic analogues. Over 50% of all modern clinical drugs are of natural product origin and natural products play an important role in the drug development programmes in the pharmaceuticals industries.