Abstract

Recently, an inverse correlation between bean consumption and age related diseases such as breast and prostate cancer has been established. Furthermore, beans can easily be grown with minimum cost across the globe. In the present study, we investigated anthocyanin, proanthocyanidin and antioxidant activity of five (black, brown, white, brown and black spotted) common bean species (Phaseolus vulgaris L.) grown in Mashonaland Central, Zimbabwe. The five common bean species exhibited variations in anthocyanins, proanthocyanidin and antioxidant activity. Anthocyanin content estimated using a UV spectrophotometer by a pH differential method varied significantly in the order: brown (0.59 ± 0.01) > black (0.43 ± 0.01) > white  (0.28 ± 0.01). Brown seeds also exhibited superior proanthocyanidin contents (0.18 mg g^-1 ± 0.01). Bean seeds consisting of greater amounts of anthocyanins exhibited superior antioxidant activity. All species showedantioxidant activity which was concentration-dependent. The present results suggest that screening programs should be done to come up with superior bean species for targeted animal feeds and human food.

Key words: Anthocyanin, proanthocyanidin, antioxidant activities, bean species, Phaseolus vulgaris L.