Antimicrobial Evaluation of Plant Parts of Rauwolfia Vomitoria

Aims: This study was aimed at evaluating the antimicrobial activities of fractions of Rauwolfia vomitoria against some isolates including; Salmonella typhi, Escherichia coli, Candida albicans, Aspergillus niger, Microsporon canis, and Trichophyton rubrum.

Methodology: Primary extraction was done on the dried and pulverized plant samples (leaves, barks, and root) using methanol, after which the crude extracts was fractionated using butanol, ethyl acetate, and n-hexane respectively. The samples were duly labelled according to the plant parts and solvents used. Agar diffusion and dilution methods on Mueller-Hinton agar (MHA) and Sabouraud dextrose agar (SDA) where used to determine the minimum inhibitory concentrations (MIC) and minimum bactericidal and fungicidal concentrations (MBC/MFC) respectively. The percentage inhibition diameter growth (PIDG) of the extracts and fractions were also determined.

Results: From the results, eleven (11) samples showed inhibitory activity on one or more of the test isolates. Extended spectrum activity was observed with five (5) of the samples, including; RVL ethyl acetate, RVL n-hexane, RVB crude, RVR crude, and RVR ethyl acetate against S. typhi, E. coli, and M. canis. Antifungal activity was observed only against M. canis. The ethyl acetate fraction of the leaves (RVLE) and crude methanol extract of the bark (RVBC) gave the least MIC both against M. canis at a concentration of 25 mg/ml, while the ethyl acetate fraction of the leaves (RVLE) at 12.5 mg/ml also against M. canis gave the least MBC/MFC. Using the inhibition zone diameters (IZD), the obtained PIDG showed apparently that the ethyl acetate fraction of the leaves (RVL ethyl acetate) was the most active against S. typhi (28.57%) and E. coli (20%).

Conclusion: The study lends support to the traditional use of the plant especially in treating gastro intestinal tract and skin infections.