Release of phenolic compounds and antioxidant capacity of Chinese hawthorn 'Crataegus pinnatifida' during in vitro digestion

In order to evaluate the release of phenolics and the changes in antioxidant activities, fruits of Crataegus pinnatifida were subjected to in vitro digestion including simulated oral, gastric, small/large intestine digestion. Results showed that totally 37.41 ± 3.09 and 31.51 ± 2.35 mg GAE/g fruit, DW of phenolics were released for Shanlihong and Dajinxing, respectively, and the phenolics released were mainly flavonoids. Catechin, chlorogenic acid, procyanidine B2, epicatechin, paracoumaric acid, hyperoside and isoquercitrin were identified in the soluble fractions by high-performance liquid chromatography (HPLC). Results indicated that procyanidine B2, epicatechin, chlorogenic acid and catechin are four major released antioxidants. Oxygen radical absorption capacity and rapid peroxyl radical scavenging capacity were significantly positive-correlated with the release amount of total phenolics or flavonoids, demonstrating the major roles of phenolics and flavonoids in antioxidant activities. Our results implied that Shanlihong and Dajinxing could be considered as good sources of natural antioxidants.