Screening Togolese medicinal plants for few pharmacological properties

Abstract

Terminalia macroptera Guill. et Perr. (Combretaceae), Sida alba L. (Malvaceae), Prosopis africana Guill et Perr. Taub. (Mimosaceae), Bridelia ferruginea Benth. (Euphorbiaceae), and Vetiveria nigritana Stapf. (Asteraceae) are traditionally used in Togolese folk medicine to treat several diseases including microbial infections. This study aimed to investigate the antimicrobial, antioxidant, and hemolytic properties of the crude extracts of the above-mentioned plants. The antimicrobial and the antioxidant activities were assayed using the NCCLS microdilution method and the DPPH free radical scavenging, respectively. Human A+ red blood cells were used to perform the hemolytic assay. Phenolics were further quantified in the extracts using spectrophotometric methods. Minimal inhibitory concentrations in the range of 230–1800 µg/ml were recorded in the NCCLS broth microdilution for both bacterial and fungal strains with methanol extracts. The DPPH radical scavenging assay yielded interesting antioxidant activities of the extracts of P. africana and T. macroptera (IC50 values of 0.003 ± 0.00 µg/ml and 0.05 ± 0.03 µg/ml, respectively). These activities were positively correlated with the total phenolic contents and negatively correlated with the proanthocyanidin content of the extracts. The hemolytic assay revealed that great hemolysis occurred with the methanol extracts of T. macroptera, S. longepedunculata, and B. ferruginea. These results support in part the use of the selected plants in the treatment of microbial infections. In addition, the plant showed an interesting antioxidant activity that could be useful in the management of oxidative stress.

Keywords: Antimicrobial; antioxidant; hemolytic; phenolics