Structures and antioxidant activity of anthocyanins in many accessions of eggplant and its related species

Anthocyanins were detected in extracts from the peels of 123 accessions of eggplant (Solanum melongena) and its related species. Their anthocyanin profiles were classified into four types, including known Japanese eggplant type (type 1) and non-Japanese eggplant type (type 2). Although most of the eggplant accessions had one of the two known profiles, one accession had a novel profile (type 3). Two accessions of related species showed another novel profile (type 4). The major anthocyanins were identified as delphinidin 3-(p-coumaroylrutinoside)-5-glucoside (nasunin) (type 1), delphinidin 3-rutinoside (type 2), delphinidin 3-glucoside (type 3), and petunidin 3-(p-coumaroylrutinoside)-5-glucoside (petunidin 3RGc5G) (type 4). Delphinidin 3-caffeoylrutinoside-5-glucoside (delphinidin 3RGcaf5G) was isolated from the hybrid (F1) plants of a type 1 cultivar and a type 3 germplasm. Among the five purified anthocyanins, delphinidin 3RGcaf5G showed the highest radical-scavenging activities toward both 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and linoleic acid radical, followed in order by nasunin and petunidin 3RGc5G.