Preliminary studies on in vitro antioxidant and retardation of essential carbohydrate hydrolysing enzymes by some indigenous South African medicinal plants

•Leaf extracts of 11 South African plants were screened as potential hypoglycaemia agents.•Six species had high flavonoid, total phenolic and/or condensed tannin content.•These six species also had good antioxidant activity in two assays (DPPH and FRAP).•They had high α-glucosidase and moderate pancreatic α-amylase inhibitory potential.•Endostemon obtusifolius, Combretum kraussi and Catha edulis were the most promising therapeutic agents.