Free radical scavenging activity, phenolic contents and cytotoxicity of selected Nigerian medicinal plants

► We investigate Nigerian plant extracts to validate their use in traditional medicine. ► Plant extracts are non-toxic to human blood mononuclear cells, and A2.01 cell line. ► Antioxidant activities correlate with phenolics and flavonoid contents of extracts. ► Lipid peroxidation inhibition is related to extract phenolic and flavonoid content. ► Lipid peroxidation inhibition and antioxidant activity could yield medicinal potency.