Methanolic extract of <i>Nauclea diderrichii</i> (stem-bark) show anti-microbial, anti-oxidant and anti-inflammatory bioactivities

Abstract

The aqueous stem-bark extract of the tropical plant Nauclea diderrichii is used in ethnomedicine to manage symptoms of rheumatism through minimally examined mechanisms. The objective of the study is to examine the scientific bases for the ethnomedicinal use of the plant for the management of rheumatism. As part of this effort to explain its ethnomedicinal efficacy, this study compared and contrasted the anti-microbial, anti-oxidant and anti-inflammatory activities of the methanolic extract with that of the diethylether extract. Broth dilution assay, DPPH radical scavenging assay and carrageenan-induced foot swelling of 7-day old chicks were utilized for the experimental assessment of the bioactivities of Nauclea diderrichii. Polar methanolic extract exhibited a higher antioxidant status in vitro as estimated quantitative differences in total phenolic content, in total antioxidant capacity and in DPPH and H2O2 radical scavenging converged to show the methanolic extract as a more potent anti-oxidant. The methanolic extract also possess better in vivo anti-inflammatory activity as demonstrated by the 1.5-fold lower ED50 relative to that of the diethylether. The methanolic extract demonstrated better broad-spectrum anti-microbial activity against a panel of six clinical isolates of bacterial and fungi pathogens in vitro. The relative strength of the bioactivities of the methanolic extract derives from a higher slew of phytochemical content that is a 3-fold difference larger. The results of this study support the beneficial effect of Nauclea diderrichii in its continuing ethnomedicinal use to target rheumatism chemotherapeutically.