Peak Journal of Medicinal Plant Research Vol.1 (2):13-18, July, 2013 https://www.peakjournals.org/sub-journals-PJMPR.html ©2013 Peak Journals Full Length Research Paper Phytochemical evaluation and antibacterial activity: A comparison of various extracts from some Nigerian trees Tor-Anyiin, Terrumun Amom* and Anyam, John Vershima Accepted 23 July, 2013 Six Nigerian trees; Stereospermum kunthianum, Syzygium guineense (stem barks); Maytenus senegalensis, Piliostigma thonningii, Terminalia avicennoides and Burkea Africana (root barks); which are important in African ethno-medicine were investigated. Phytochemical analysis of their alcoholic extracts revealed the presence of tannins, saponins and terpenoids in all the plants; flavonoids absent only in P. thonningii, and alkaloids found in B. Africana and M. senegalensis. The inhibitory properties of different extracts from these plants at 150 mg/ml were performed on select organisms: Escherichia coli, Salmonella typhii and Staphylococcus aureus. Zones of inhibition ranging from 0 to 8 mm were observed and compared graphically. All extracts from P. thonningii and S. guineense were inactive against all the test microbes. Key words: Phytochemical analysis, antimicrobial activity, extracts, root bark, stem bark, Nigerian trees. INTRODUCTION Seeking remedies for humans from the environment has been the basis of therapeutics. Plants constitute a rich untapped pool of natural resource. Man has depended on plants as a source of food, shelter, medicine, clothing etc. Medicinal plants are an important natural wealth of a country, serving as therapeutic agents and important raw materials for the manufacture of modern medicine. Development of resistance to most available antimicrobial agents and high cost of treatment consequent upon this resistance has necessitated a search for new, safe, efficient and effective agents for the management of infection. The primary focus of these investigations naturally should be on establishing the efficacy and toxicity of medicinal plants commonly employed in ethnomedicine. Burkea africana Hook (Caesipinoioideae), Maytenus senegalensis (Lam.), Excell (Celastroceae), Piliostigma thonningii (Schum.), Milne-Redhead (Caesipinoioideae), Stereospermum kunthianum Cham. (Bignoniaceae), Syzygium guineense Wild. DC (Myrtaceae) and Terminalia avicennoides Guill. & Perr. (Combretoceae) are important plants in Nigerian phytomedicine (Falodun et al., 2006; Domo and Kela, 2009; Ugbabe et al., 2010; Igoli et al., 2011; Mann et al., 2011a). Some have been variously studied for anti-venom and toxic effects (Igoli et al., 2011), anti inflammatory and anti-oxidant effects (Abubakar et al., 2007; Danjuma et al., 2011; Atawodi, 2005), antidiarrhoeal properties (Tanko et al., 2011), antischistosomal behavior (Domo and Kela, 2009), antiplasmodial (Bernadina et al., 2002; Madara et al., 2012), antimicrobial effects (Audu et al., 2007; Ugbabe et al., 2010), and antitrypanosomal tendencies (Atawodi et al., 2011). Many medicinal agents have been isolated from some of these plants (Gbogomu-Tih et al., 1985; Bernadina, et al., 2002; Djoukeng et al., 2005;Falodun et al., 2009; Mann et al., 2011b). Phytochemicals are known to vary with variations in climate, weather, soil conditions as well as time of collection. Though these plants have been variously investigated, their phytochemical and antimicrobial properties have never been compared. Owing to their ethnomedicinal importance and compounds isolated and identified from some of them, it became expedient to examine them under identical conditions. This study compares these important plants along the lines of their behavior towards three important pathogens; Escherichia coli, Staphylococcus aureus and Salmonella typhi at a concentration of 150 mg/ml. Phytochemical screening of the plants have also been carried out with Department of Chemistry, University of Agriculture P.M.B. 2373, Makurdi, Nigeria. *Corresponding author. E-mail: toranyiint@yahoo.com. Tel.: +2348037816585.