Isolation Identification and Characterization of Diterpenes from the Stem bark of Detarium Microcarpum

Abstract

The antibacterial activity of the stem bark of Detarium microcarpum was investigated with the aim of isolating the most active ingredient. Extraction solvents used to prepare the crude extracts of the stem bark were, n-hexane, ethyl acetate, chloroform, methanol. Test bacteria included Escherichia coli, Salmonella enteriditis, Shigella dysenteriae, Staphylococcus aureus and Vibro cholerae. The extracts demonstrated a wide range of antibacterial activity on the microorganisms, with the ethyl acetate crude extract being the most active. Using liquid vacuum chromatography over silica gel, the extract was eluted with n- hexane, ethyl acetate and methanol and fifty- five fractions labeled Gl - G55 were obtained. Further antibacterial assays of the fractions led to the identification of fraction G34 as the most active fraction. This fraction was subjected to spectroscopic analysis using NMR, [(1H -1H NMR, 13C-NMR) and 2D-NMR (COSY and HMBC)]. The results showed good agreement with reported data on Copalic acid, a diterpene with chemical formula C O H O . This compound is 2 34 2 the most active ingredients of this plant and is likely to be responsible for its antibacterial activities.