Chemical Composition and Antimicrobial Activities of <i>Picralima nitida</i> Stem Bark Extracts

Abstract

Picralima nitida has varied applications in West African traditional medicine. The stem bark of the plant was  successively extracted with n-hexane and chloroform using cold extraction techniques. The phytochemical analysis and antimicrobial activity of P. nitida extracts were determined using established methods. Chemical composition of the n-hexane extract was determined by GC-MS. The phytochemical screening of the n-hexane and chloroform extract revealed the presence of alkaloids, phenols, glycosides, eugenols, terpenoids, reducing sugars and proteins. The GC-MS of the n-hexane extract of P. nitida stem bark revealed the presence of 54 compounds, representing 100% of the total identified components. The major components detected were found to be dodecanoic acid (lauric acid)(18.34%), 9 octadecanoic acid (Stearic acid) (7.49%) , n-hexadecanoic acid (palmitic acid) (5.95%) while among the minor component were phytol (1.73%) and 5cholesten-3-Beta, 2,6-dioic-16-one (0.36%). The result of the antimicrobial activity revealed that the n-hexane extract exhibited the highest inhibitory activity against Escherichia coli while the chloroform extract exhibited the highest inhibitory activity against Staphylococcus aureus. The activity of the extracts against the fungi isolates were found to insignificant at all test concentrations. The MIC value for of n-hexane was found to be 150 and125mg/ml for S. aureus and E. coli respectively while that of chloroform extract was found to be 125 and 125mg/ml for S. aureus and E. coli respectively. This study has shown that the n-hexane extract was more active against the Gram negative bacteria while the chloroform extract was more active against the Gram-positive bacteria .This investigation therefore revealed that the stem bark extracts possess some antimicrobial properties and could be a promising source of novel drugs.