2.6. 2,2-Diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activity
The DPPH assay for the determination of free radical scavenging activity was done as outlined by Moyo et al. (2010). Methanolic DPPH (100 µM) was prepared freshly before the assay. Decrease in the purple colouration of the reaction mixtures was read at 517 nm in a Cary 50 UV–vis spectrophotometer. Ascorbic acid was used as a standard antioxidant. The assay was done using four replicates. The free radical scavenging activity (RSA) was calculated according to the formula: