We investigated the effects of in vitro human digestion on the content and bioavailability of onion quercetin and grape resveratrol caused by the composition of saliva or gastric, duodenal, or bile juice. We observed the digestibility of extracted onion quercetin and grape resveratrol, respectively, in the small intestine of the in vitro human digestion system. By liquid chromatography–mass spectroscopy, we found that the degradation of quercetin and resveratrol was influenced by small intestine digestion. Before and after in vitro human digestion, the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities of homogenized water- and ethanol-extracted grapes were higher than those of onion extracts. DPPH radical scavenging activity in both quercetin and resveratrol was decreased by in vitro digestion. These results will improve our understanding of how human digestion influences the contents and free radical scavenging activities of quercetin and resveratrol.

中文翻译：

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体外人体消化过程中洋葱槲皮素和葡萄白藜芦醇含量和生物利用度的变化。

我们调查了体外人消化对唾液或胃液，十二指肠汁或胆汁的成分引起的洋葱槲皮素和葡萄白藜芦醇含量和生物利用度的影响。我们观察了提取的洋葱槲皮素和葡萄白藜芦醇在人体体外消化系统的小肠中的消化率。通过液相色谱-质谱联用，我们发现槲皮素和白藜芦醇的降解受到小肠消化的影响。在体外人体消化之前和之后，均质水和乙醇提取的葡萄的2，2-二苯基-1-吡啶并肼基（DPPH）清除自由基的活性高于洋葱提取物。槲皮素和白藜芦醇中的DPPH自由基清除活性通过体外消化而降低。