Physicochemical properties, bioaccessibility and antioxidant activity of the polyphenols from pine cones of Pinus koraiensis.

This study investigated the physicochemical properties, bioaccessibility and in vitro antioxidant ability of the polyphenols isolated from the pine cones of Pinus koraiensis (PKP) under the simulated gastrointestinal digestion. The results found that PKP was mainly composed by derivatives of apigenin, phloretin, quercetin, myricetin, ellagitannin, and chlorogenic acid, and possessed the flat and smooth lump surface morphology. Through respective establishment of saliva, gastric fluid and small intestinal fluid digestive model in vitro, the compositions of phenolic compounds were totally different due to biotransformation. Compared with the phenolic composition of undigested PKP, the derivatives of apigenin, quercetin and ellagitannin were still detected after simulated digestion. A decrease of antioxidant capacity on free radical in vitro was observed throughout the simulated digestion processes, corresponding to the variation in phenolic content and composition. Our results highlighted that gastrointestinal digestion process might essentially influence the absorption of polyphenols, leading to the reduction of bioavailability.