Evaluation of Selected Nigerian Medicinal Plants for Antioxidant, Antimicrobial and Cytotoxic activities

Abstract Background: Increased exposure to pathogens and free radicals contributed to the high incidence and mortality rate of various cancers in Nigeria and globally. Promotion of scientific research on medicinal plants in collaboration with traditional health practitioners to validate claims made on safety, efficacy and quality of traditional medicinal plants in the treatment of cancer is imperative. This study aims at screening extracts of selected Nigerian medicinal plants used traditionally for cancer treatment for antioxidant, antimicrobial and cytotoxic activities towards identification of potential source of new anticancer agents.Methods: Twenty-one extracts from sixteen medicinal plants species were screened for their cytotoxicity on RD, HeLa and Hep-2 cancer cell lines using MTT assay. The DPPH radical scavenging activity of the extracts as well as their Total Phenolic Content (TPC) were evaluated. The extracts were also evaluated for their antimicrobial activity using spectrophotometric growth inhibition method. Results: Extracts of Tetrapleura tetrapleura and Xylopia aethiopica showed high DPPH inhibitory activity and phenolic content. Extracts of X. aethiopica and Anchomanes difformis showed broad spectrum of antibacterial activities while root extracts of Crotolaria retusa and T. tetraptera exhibited antifungal activities comparable (P<0.05) to Ketoconazole. Extracts of Capcicum frutescens, Aspilia africana, X. aethiopica, T. tetraptera and C. retusa showed broad spectrum of cytotoxic activities.Conclusions: Extracts of T. tetraptera and X. aethiopica demonstrated satisfactory activities in all the biological tests which could be linked to their high phenolic contents. The findings support the ethno-medicinal uses of most of the tested medicinal plants.