The root-bark of Dalbergia saxatilis (Fabaceae), a plant used traditionally in ethnomedicine in Nigeria, was extracted with 95% ethanol to give the crude extract. The crude extract was partitioned into acidic, basic and neutral polar and non-polar fractions. Preliminary phytochemical screening of D. saxatilis root bark crude extract revealed the presence of alkaloids, tannins, phenols, flavonoids, terpenoids, and glycosides. The antimicrobial screening was carried out on the crude extract and the fractions and all the samples were active against the test organisms: Staphylococcus aureus, Salmonella .typhi, Escherichia coli, Bacillus substilis and Candida albicans .The basic fraction was the least active against S. typhi while the neutral non-polar (hexane) fraction was the most active against B. substilis. Column chromatographic separation of the biologically active hexane fraction gave fractions which on GC-MS analysis and by comparison with the standard library computer MS data led to the identification of two azulene-type sesquiterpenes,1, 2,3,5,6, 7,8,8a-octahydro-1,4-dimethyl-7-(1-methylethenyl)azulene,and1H-3a,7-methanoazulene,2,3,4,7,8,8a-hexahydro-3,6,8,8-tetramethyl-.The presence of these constituents in the plant extract may account for the antimicrobial properties of the plant. Thus, the root bark of D. saxatilis can be harnessed for anti-infective purposes.
