Advances in Natural and Applied Sciences, 2(1): 31-34, 2008 ISSN 1995-0772 © 2008, American Eurasian Network for Scientific Information This is a refereed journal and all articles are professionally screened and reviewed ORIGINAL ARTICLE 31 Corresponding Author: Liasu, M.O., Department of Pure and Applied Biology, Ladoke Akintola University of Teghnology, Ogbomoso. E-mail: laideliasu@yahoo.com Antimicrobial Activity of Aqueous and Ethanolic Extracts from Tithonia diversifolia and Bryum Coronatum Collected from Ogbomoso, Oyo State. Nigeria Liasu, M.O. and Ayandele, A.A. Department of Pure and Applied Biology, Ladoke Akintola University of Teghnology, Ogbomoso. Liasu, M.O. and Ayandele, A.A.,: Antimicrobial Activity of Aqueous and Ethanolic Extracts from Tithonia diversifolia and Bryum Coronatum Collected from Ogbomoso, Oyo State. Nigeria,: Adv. in Nat. Appl. Sci., 2(1): 31-34, 2008 ABSTRACT Bioassays for antimicrobial activities were carried out using stem, leaves and flowers of Tithonia diversifolia and Byrum coronatum plants. Crude aqueous and ethanolic extracts from leaves, stem and flowers of T. diversifolia and whole plant of B. coronatum were prepared and tested against gram positive bacteria i.e. Bacillus subtilis and Staphylococcus sp, gram negative bacteria Proteus vulgaris, Pseudomonas aeruginosa and Escherichia coli and fungi i.e. Penicillium atrovenetium, Aspergillus niger, Geotrichum candidium and Fusarium flocciferum .Both the aqueous and ethanolic extracts showed considerable activity against all the test organisms while ethanolic extracts of leaves and stem of T. diversifolia and B. coronatum, aqueous extract of T. diversifolia showed no activity against Proteus vulgaris. Both the aqueous and ethanolic extracts showed considerable antifungal activity against all the test fungi except the aqueous extracts of T. diversifolia leaf and B coronatum which showed no activity against Penicillium atrovenetium. The Minimum Inhibitory Concentration MIC of the plant extracts ranged from 0.01 mg/ml to 100 mg/ml. The antibacterial and antifungal activities of both the ethanolic and aqueous plant extracts were comparable to those of selected chemical antibiotics suggesting their potential as alternatives to orthodox antibiotics in the treatment of infections caused by these microorganisms. Key words: Bioassays, Ethanolic extract, Antimicrobial activity, Agar diffusion, Minimum inhibition Concentration (MIC) INTRODUCTION Medicinal plants are gifts of nature to cure limitless number of diseases among human beings (Bushra and Ganga, 2003). The abundance of plants on the earth’s surfaces has led to an increasing interest in the investigation of different extracts obtained from traditional medicinal plants as potential sources of new antimicrobial agents. (Bonjar and Farrokhi, 2004). Researches have shown that all different parts of the plants which include; stem, root, flower, bark, leaves, e.t.c. possess antimicrobial property, work of Jalalpure et al., 2004, showed that the extracts of flowers and seeds of C. auriculata possess antidiabetic activity. Recently several workers have reported antibacterial activities of local plants i.e. Euphorbia hirta (Ogbulie et al, 2007), Kigelia africana (Omokehin et al 2007), Hibiscus sabdariffa (Olaleye 2007) and Mucuna pruriens (Salau and Odeleye, 2007). Tithonia diversifolia Hemsley. Gray is a plant belonging to the family asteraceae (compositae) found widely distributed” throughout the humid and sub-humid tropics in central and south America, Asia and Africa. Chemical