Betulinic Acid from Antimicrobial Root Wood Extract of Dalbergia saxatilis Hook f.(Fabaceae)

Abstract

Aims: The root wood of Dalbergia saxatilis was studied to assess its antimicrobial activity and chemical constituents and confirm its traditional medicinal uses. Study Design: The source of the plant was identified and the plant material was collected at a particular time of the year and authenticated. The crude 95% ethanol extract of the dry root wood was obtained and screened for phytochemicals and antimicrobial activity against pathogens of economic interests. A process for isolation and identification of bioactive components was then developed using standard procedures. Place and Duration of Study: The study was undertaken between October 2011 and November 2012 at the Department of Chemistry, University of Abuja, Nigeria. Methodology: The 95% ethanol crude extract was obtained by percolation and then fractionated into acidic, basic, polar and non-polar neutral fractions. The crude extract and fractions were subjected to antimicrobial screening against Staphylococcus aureus, Escherichia coli, Bacillus subtillis and Streptococcus viridans. The crude extract was also subjected to phytochemical screening. The active non-polar neutral fraction was purified using flash column chromatography. The isolates were characterized by spectral analyses. Results: The extracts, with the exception of the acidic fraction, were found to possess antimicrobial activity against some of the test organisms, particularly E. coli and B. subtilis. Phytochemical screening of the crude 95% ethanol extract showed the presence of phenols, flavonoids, sterols, terpenoids, carbohydrates and saponins. Column chromatography of the antimicrobial non-polar neutral fraction gave a partially pure compound which on spectral analyses led to the identification of the previously known bioactive pentacyclic triterpenoid, betulinic acid. Conclusion: This is the first report of the presence of betulinic acid in the genus, Dalbergia. Based on this a crude management drug for some globally important infections such as HIV/AIDS, malaria and cancer may be formulated using betulinic acid as a biomarker.