ANTIOXIDANT ACTIVITY, DNA DAMAGED PROTECTION AND APOPTOSIS INDUCTION POTENTIAL OF VERNONIA AMYGDALINA LEAF EXTRACTS

The challenges of free radicals and tumour promoting agents are on the increase and this informed investigation of the antioxidant property and anticancer potential of Vernonia amygdalina, a most common medicinal vegetable in Nigeria. The leaf of Vernonia amygdalina was extracted in methanol and partitioned into hexane, ethyl acetate and aqueous layers successively. Activity guided fractionation further subjected the active ethyl acetate fraction to vacuum liquid chromatography (VLC). The antioxidant activity of the extracts was measured by the DPPH radical scavenging assay. The anticancer potential of the plant extracts was assessed by the DNA nicking assay and apoptosis induction assay. The sensitivity of the mitochondrial membrane transition pore was determined by studying the rate of change in absorbance at 540 nm under energized and de-energized conditions using Spectrum Lab UV-visible spectrophotometer. The antioxidant activity of the extracts varied considerably with respect to IC₅₀ values. The results proved that V. amygdalina extracts had significant reduction in the formation of nicked DNA but demonstrated increased native form of DNA. The column fractions induced apoptosis in isolated rat hepatic mitochondria by increasing the mitochondrial membrane permeability pore opening. The findings showed that V. amygdalina have constituents that possess promising antioxidant and anticancer properties.