At the interface of antioxidant signalling and cellular function: Key polyphenol effects

Abstract

The hypothesis that dietary (poly)phenols promote well‐being by improving chronic disease‐risk biomarkers, such as endothelial dysfunction, chronic inflammation and plasma uric acid, is the subject of intense current research, involving human interventions studies, animal models and in vitro mechanistic work. The original claim that benefits were due to the direct antioxidant properties of (poly)phenols has been mostly superseded by detailed mechanistic studies on specific molecular targets. Nevertheless, many proposed mechanisms in vivo and in vitro are due to modulation of oxidative processes, often involving binding to specific proteins and effects on cell signalling. We review the molecular mechanisms for 3 actions of (poly)phenols on oxidative processes where there is evidence in vivo from human intervention or animal studies. (1) Effects of (poly) phenols on pathways of chronic inflammation leading to prevention of some of the damaging effects associated with the metabolic syndrome. (2) Interaction of (poly)phenols with endothelial cells and smooth muscle cells, leading to effects on blood pressure and endothelial dysfunction, and consequent reduction in cardiovascular disease risk. (3) The inhibition of xanthine oxidoreductase leading to modulation of intracellular superoxide and plasma uric acid, a risk factor for developing type 2 diabetes.

Modulation of VEGF signaling in a mouse model of diabetes by xanthohumol and 8‐prenylnaringenin: Unveiling the angiogenic paradox and metabolism interplay

“…MAPK directly up‐regulates pro‐inflammatory mediators such as IL‐1β and NF‐κB that are augmented in T2DM. In contrast, these animals exhibit a reduction in the number of vessels in left ventricle, which can be explained by the decreased VEGF‐A levels and VEGFR‐2 signaling pathway impairment.…”

Steam radish sprout (Raphanus sativus L.): active substances, antioxidant activities and non‐targeted metabolomics analysis

“…Radish sprouts ( Raphanus sativus L.) are a rich source of versatile biologically active compounds. In addition to the general nutrients found in most vegetables such as polyphenols and vitamin C (Li et al , ; Yamagata et al , ; Kerimi & Williamson, ), radish sprouts also contain isothiocyanates (the degradation products of glucosinolates), with documented antioxidant, anticancer and anti‐inflammatory activities (Martinez‐Villaluenga et al , ). However, we previously found that these active substances are highly vulnerable to external environmental conditions owing to the high moisture content of sprouts (Pi et al , ; Li & Zhu, ).…”

Full 1H and 13C NMR spectral assignment of conjugated valerolactone metabolites isolated from urine of black tea consumers by means of SPE‐prepLC–MS–LC–MS‐NMR

“…The health benefits of tea have been linked to the presence of polyphenols, which are phytochemicals that share the motif of an aromatic ring with two or more hydroxyl groups. The mechanism of their direct antioxidant activity in the body has been abandoned, instead more specific and subtle effects of polyphenols and their metabolites have been proposed . It is now well appreciated that direct bioavailability of tea polyphenols is low, but their metabolites enter circulation at significant concentrations, in particular those originating from gut microbial catabolism .…”

“…The mechanism of their direct antioxidant activity in the body has been abandoned, instead more specific and subtle effects of polyphenols and their metabolites have been proposed. [5,6] It is now well appreciated that direct bioavailability of tea polyphenols is low, but their metabolites enter circulation at significant concentrations, in particular those originating from gut microbial catabolism. [7] These catabolites can undergo different conjugations by the human host, which adds significant compositional diversity to the circulating metabolites.…”