Abstract: The contents of total phenols and flavonoids in artichoke bud juices prepared from receptacles and inner and outer bracts before and after gastrointestinal digestion in vitro were compared. Their antioxidant capacity was evaluated by four methods: total reducing power, and 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation and superoxide anion (O2-·) radical scavenging capacity. The results showed that the content of total phenols in receptacle juice was 2.46 mg/mL, which was 1.13 and 1.94 times higher than inner and outer bract juices, respectively. The content of total flavonoids in receptacle juice was 6.53 mg/mL, which was 1.15 and 2.06 folds increased relative to inner and outer bract juices. The antioxidant capacities of the three juices decreased in the following order: receptacle juice > inner bract juice > outer bract juice, and their radical scavenging capacity increased with phenolic concentration. After being treated with either simulated gastric juice or gastric acid, the antioxidant activity of receptacle juice was significantly enhanced (P < 0.05), whereas this was reversed by subsequent treatment with simulated intestinal juice. Therefore, pepsin, gastric acid, and trypsin could promote the release of antioxidant factors, thus improve antioxidant capacity.

Key words: artichoke, total phenols, total flavonoids, antioxidant activity, in vitro gastrointestinal digestion