Influence of boiling and subsequent phases of digestion on the phenolic content, bioaccessibility, and bioactivity of Bidens pilosa (Blackjack) leafy vegetable

The effects of boiling and in vitro human simulated digestion on phenolic compounds and bioactivity of the African leafy green vegetable, Bidens pilosa, known as Blackjack in South Africa, was investigated and compared to the leafy green vegetable Spinacia oleracea (Spinach). Metabolites such as 3-caffeoylquinic acid, catechin, 4-caffeoylquinic acid, quercetin-3-O-robinobioside, rutin and quercetin-3-O-glucoside were dominant in the boiled methanolic compared with the raw methanolic extracts of the Blackjack. The total phenolic and flavonoid content generally decreased after in vitro complete digestion for both raw and boiled extracts, indicating that pH and environment associated with digestion alters the bioactivity of the extracted phenolics. Both leafy green vegetables had beneficial effects, but all Blackjack extracts were more effective in preventing the AAPH-mediated oxidation of Caco-2 cells, low-density lipoprotein and deoxyribonucleic acid than those of the spinach. This study identified the health benefits of eating Blackjack and therefore, the cultivation and consumption of this leafy green vegetable should be promoted.