Preliminary Screening Indicates Promising Antimicrobial Properties of the Stem Bark Extracts of Macaranga rosea

Background/Purpose: Medicinal plant extracts with potent antimicrobial activity are potentially useful sources of new and novel antimicrobial agents. We investigated the extracts from the stem bark of Macaranga rosea antimicrobial activity. Methods: Cold extraction procedures were used to obtain extracts followed by standard qualitative assays for phytochemicals. Agar well diffusion and macrobroth dilution assays were used to determine antimicrobial effects of the extracts. Thin layer and column chromatography were used to further separate the chemical entities for further clues on the active constituents. Results: The Methanolic extracts provided the greatest diversity of phytochemicals including reducing sugars, anthraquinones, Phlobatannins, glycosides, steroids, tannins, saponins and alkaloids. Ethanol extracts were the most effective against Staphylococcus aureus and Pseudomonas aeruginosa whilst methanolic extracts were more effective against Candida albicans. The MIC and MBC values were lowest with the methanolic extracts for S. aureus with values of 3.12 and 6.25 mg/ml for MIC and MBC respectively. For P. aeruginosa, the ethanolic extract gave the best MIC and MBC values of 1.56 and 3.12 mg/ml respectively. For C. albicans, the best MIC and MFC values were obtained from methanolic extracts at 0.78 and 3.12 mg/ml respectively. Fractions of the methanolic extracts were active against Pseudomonas aeruginosa and Candida albicans but not S. aureus at 250μg/ml. Conclusion: This study demonstrated the phytochemical richness and wide spectrum of antimicrobial activity of Macaranga rosea. The plant is currently endangered and this study appears to be the first documented on its antimicrobial properties.