Antioxidant properties of some commonly consumed and underutilized tropical legumes

The antioxidant properties of some commonly consumed [cowpea (Vigna unguiculata)] and underutilized [pigeon pea (Cajanus cajan) and African yam bean (Sphenostylis sternocarpa)] legumes were assessed with regard to their Vitamin C, total phenol, and phytate content, as well as antioxidant activity as typified by their reducing power and free radical scavenging ability. The Vitamin C content of the cowpeas ranged from 0.5 to 0.9 mg/100 g, while that of underutilized legumes were 0.9 mg/100 g for pigeon pea and 0.8 mg/100 g for African yam beans. The phenol content of the cowpeas were 0.3–1.0 mg/g, African yam bean had 0.7 mg/g total phenols, while pigeon pea contained 0.4 (white) and 1.2 mg/g (brown) total phenol content, respectively. The phytate content of all the legumes [cowpea (2.0–2.9%), pigeon pea (2.0–2.4%), African yam beans (2.4%)] analyzed were generally high, while the reducing power and free radical scavenging ability for all the legumes were very low except in African yam beans (23.6%), cowpea brown (29.9%), and pigeon pea brown (54.5%) that had a relatively high free radical scavenging ability. Therefore, one of the commonly consumed cowpea V. unguiculata (brown) and underutilized legumes C. cajan (brown) and S. sternocarpa could be considered as a functional food due to their relatively higher antioxidant activity (free radical scavenging ability and redox potential) which could be as a result of their relative higher total phenol content.