Polyphenols content and antioxidant capacity of eggplant pulp

The influence of organic and conventional farming practices on the phenolic content in eggplant samples belonging to two cultivars, Blackbell (American eggplant) and Millionaire (Japanese eggplant) grown under similar environmental conditions was evaluated. Phytochemical investigation of the eggplant extracts showed that N-caffeoylputrescine, 5-caffeoylquinic acid, and 3-acetyl-5-caffeoylquinic acid made up the bulk of total eggplant phenolics. In addition, this is the first report on identification of trace quantities of three additional flavonols, namely, quercetin-3-glucoside, quercetin-3-rhamnoside, and myricetin-3-galactoside in freeze-dried eggplant pulp. The phenolic content of the conventionally grown Blackbell variety was marginally higher or equal to those grown organically. However, the phenolic content of the Millionaire organic variety was much greater than the conventionally grown samples. Eggplant extract inhibition of cupric-ion mediated oxidation of low-density lipoproteins was highly correlated with the content of 5-caffeolquinic acid (R² = 0.9124), the most abundant phenolic acid identified.