Isolation, Characterization and Antimicrobial Screening of Betulinic Acid from the Stem Extract of Fadogia erythrophloea

Abstract

The stem bark of Fadogia erythrophloea (Rubiaceae) was extracted exhaustively using methanol by cold maceration. The crude extract was then sequentially partitioned into n-hexane, chloroform and ethyl acetate fractions. Purification of the chloroform fraction by column and preparative thin layer chromatography lead to the isolation of the pure compound. Structural elucidation using FTIR, 1H and C NMR spectroscopic techniques confirmed that the isolated compound was betulinic acid (a lupane-type triterpene). The antimicrobial property of the compound against gram-positive and gram-negative microbes was evaluated using well diffusion method with commercial antibiotics; ciprofloxacin and fluconazole, as controls. The antimicrobial screening revealed sensitivity of S. aureus, S. faecalis, B. cereus, E. coli, K. pneumonia, S. typhi, S. dysenteriae, C. albicans, C. Krusei; with resistance of S. pyogenes, B. subtilis, C. ulceran, P. aeruginosa to the isolated compound. The zone of inhibition ranges from 25 – 30 mm with the highest against Escherichia coli and the lowest against Klebsiella pneumonia on which both control drugs were not sensitive. The MIC and MBC / MFC values ranges from 6.25 – 25 µg/ml and 25 – 50 µg/ml respectively. The in vitro anti-microbial screening of the isolated compound (betulinic acid) supports the ethno medicinal claim on the uses of Fadogia erythrophloea for the treatment of malaria, childhood fever, dysentery diarrhea, colic and constipation.