Abstract: A total of 11 different varieties of cowpea were collected in this study to investigate their nutritional value. Total phenolic contents and total flavonoid contents were measured and correlated with antioxidant activities (ferric reducing antioxidant power, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and hydroxyl radical scavenging activity). Significant differences in phenolic contents and antioxidant activities among different varieties of cowpea were observed. The Xinza No.1 cultivar exhibited the highest levels of total phenolic content (5.59 mg GAE/g), total flavonoid content (4.12 mg CAE/g) and antioxidant activity (ferric reducing antioxidant power and DPPH radical scavenging activity). Total phenolic and total flavonoid contents showed highly significant correlations with ferric reducing antioxidant power and DPPH radical scavenging activity (P < 0.01), while weak correlation was observed with hydroxyl radical scavenging activity.

Key words: cowpea, total phenolic, total flavonoid, ferric reducing antioxidant power, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, hydroxyl radical scavenging activity