Phytochemical profiles and antioxidant capacity of improved cowpea varieties and landraces grown in Ethiopia

The phytochemical profiles and antioxidant capacities of 14 cowpea varieties (7 improved and 7 landraces) grown in Ethiopia were studied. The total phenolic, flavonoids, and monomeric anthocyanin contents (mg/100 g flour dry matter basis, db) ranged from 1210 to 1610 gallic acid equivalents, 250 to 1110 catechin equivalents and 3 to 7 cyanidin-3-glucoside equivalents, respectively. The antioxidant capacity measured using the 2,2diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH), 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ferric reducing antioxidant power (FRAP) assays ranged from 26 to 92 and 89-125 mu mol Trolox equivalent (TE)/g, and 62-90 mu mol Fe2+/g db, respectively. p-Coumaric acid followed by sinapic acid predominated in the soluble fractions while salicylic acid followed by rosmarinic acid predominated in the bound fractions. The principal component analysis showed that most landrace cowpea grains showed higher total phenolic contents and antioxidant capacities than the improved grain varieties. The results suggested that landraces should be given due attention in future planning of cowpea breeding strategies