The frequent intake of whole foods and dietary food variety is recommended due to their health benefits, such as prevention of multiple chronic diseases, including cancer, Alzheimer’s disease, cardiovascular diseases, and type 2 diabetes mellitus. Often, consuming whole fruits or vegetables showed the enhanced effects than consuming the individual dietary supplement from natural products, which is widely explained by the interactive effects of co-existing phytochemicals in whole foods. Although research relevant to interactive effects among the bioactive compounds mounted up, the mechanism of interaction is still not clear. Especially, biological influence factors such as bioavailability are often neglected. The present review summarizes the progress on the synergistic and antagonistic effects of dietary phytochemicals, the evaluating models for antioxidant interactions, and the possible interaction mechanisms both in vitro and in vivo, and with an emphasis on biological-related molecular mechanisms of phytochemicals. The research on the interaction mechanism is of value for guiding how to take advantage of synergistic effects and avoid antagonistic effects in daily diets or phytochemical-based treatments for preventing chronic diseases.

Accumulating evidence shows that oxidative stress and inflammation contribute to the development of cardiovascular disease. It has been suggested that propolis possesses antioxidant and anti-inflammatory activities. In this study, the antioxidant and anti-inflammatory effects of the main flavonoids of propolis (chrysin, pinocembrin, galangin, and pinobanksin) and propolis extract were researched. The results showed that the cellular ROS (Reactive oxygen species) levels, antioxidant enzymes, Nrf2 (Nuclear factor erythroid 2-related factor 2) nuclear translocation, and the expression of NQO1 (NAD(P)H:quinone oxidoreductase 1) and HO-1 (heme oxygenase 1) were regulated by different concentrations of individual flavonoids and propolis extract, which showed good antioxidant and pro-oxidant effects. For example, ROS levels were decreased; SOD and CAT activities were increased; and the expression of HO-1 protein was increased by chrysin. The results demonstrated that NO (Nitric Oxide), NOS (Nitric Oxide Synthase), and the activation of the NF-κB signaling pathway were inhibited in a dose-dependent manner by different concentrations of individual flavonoids and propolis extract. Moreover, the results revealed that the phytochemicals presented antioxidant effects at lower concentrations but pro-oxidant effects and stronger anti-inflammatory effects at higher concentrations. To maintain the balance of antioxidant and anti-inflammatory effects, it is possible that phytochemicals activate the Nrf2 pathway and inhibited the NF-κB (Nuclear factor kappa B) pathway.

The composition and antioxidant activity of bound phenolics in three legumes (soybean, vicia faba, and kidney bean), and their metabolism and bioaccessibility in the gastrointestinal tract were investigated in this study. The total phenolic content, total flavonoid content, and antioxidant activities (ABTS and FRAP) were evaluated. The phytochemical compositions of the three legumes after acid/alkaline hydrolysis, simulated gastrointestinal digestion, and colonic fermentation were identified and quantified by UPLC-ESI-QTOF-MS/MS and HPLC-ESI-QqQ-MS/MS. The results showed that the three legumes were rich in bound phenolic compounds, and possessed a strong antioxidant activity; among which kidney bean showed a higher bound flavonoid content and antioxidant activity than the other two legumes. Alkaline hydrolysis allowed a more thorough extraction of the bound phenolics of the three legumes than acid hydrolysis. The released contents of bound phenolics were extremely low in in vitro digestion, whereas colonic fermentation favored the release of more phenolic compounds. Kidney bean, which presented the highest bound flavonoid content and antioxidant activity, had the lowest bioaccessibility. Our study provides a wider insight into the constituents and bioavailability of bound phenolic compounds in the three legumes.