The absorption and antioxidant activity of polyphenols from grape pomace (GP) are important aspects of its valorization as a feed additive in the diet of weaned piglets. This study aimed to evaluate the presence of polyphenols from GP both in vitro in IPEC cells and in vivo in the duodenum and colon of piglets fed with diets containing or not 5% GP and also to compare and correlate the aspects of their in vitro and in vivo absorption. Total polyphenolic content (TPC) and antioxidant status (TAS, CAT, SOD and GPx enzyme activity, and lipid peroxidation-TBARS level) were assessed in duodenum and colon of piglets fed or not a diet with 5% GP. The results of UV-Vis spectroscopy demonstrated that in cellular and extracellular medium the GP polyphenols were oxidized (between λmax = 276 nm and λmax = 627.0 nm) with the formation of o-quinones and dimers. LC-MS analysis indicated a procyanidin trimer possibly C2, and a procyanidin dimer as the major polyphenols identified in GP, 12.8% of the procyanidin trimer and 23% of the procyanidin dimer respectively being also found in the compound feed. Procyanidin trimer C2 is the compound accumulated in duodenum, 73% of it being found in the colon of control piglets, and 62.5% in the colon of GP piglets. Correlations exist between the in vitro and in vivo investigations regarding the qualitative evaluation of GP polyphenols in the cells (λmax at 287.1 nm) and in the gut (λmax at 287.5 nm), as oxidated metabolic products. Beside the presence of polyphenols metabolites this study shows also the presence of the unmetabolized procyanidin trimers in duodenum and colon tissue, an important point in evaluating the benefic actions of these molecules at intestinal level. Moreover the in vivo study shows that a 5% GP in piglet’s diet increased the total antioxidant status (TAS) and decreased lipid peroxidantion (TBARS) in both duodenum and colon, and increased SOD activity in duodenum and CAT and GPx activity in colon. These parameters are modulated by the different polyphenols absorbed, mainly by the procyanidin trimers and catechin on one side and the polyphenols metabolites on the other side.

Grape pomace (GP) represents a very reliable source of polyphenols because it could be found globally as a remnant of the wine industry. During the winemaking process, two types of GP are generated: red GP and white GP, according to the produced wine, red or white. Grape pomace represents a viable source of polyphenols, mainly flavanols, procyanidins anthocyanins, and resveratrol which possess antioxidant and anti-inflammatory activities. Multiple differences were observed between red and white GP in terms of their antioxidant and anti-inflammatory activity in both in vitro and in vivo studies. Although most studies are focused on the antioxidant and anti-inflammatory effect of red grape pomace, there are still many variables that need to be taken into consideration, as well as extensive study of the white GP. It was observed that in both in vitro and in vivo studies, the GP polyphenols have a direct antioxidant activity by acting as a free radical scavenger or donating a hydrogen atom. It also possesses an indirect antioxidant and anti-inflammatory activity by reducing mitochondrial reactive oxygen species (ROS) generation, malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), interleukin-1-beta (IL-1β), interleukin-6 (IL-6), nuclear factor kappa-light-chain-enhancer of activated B cells (NF- κβ), and inhibitor of nuclear factor kappa-B kinase subunit beta (Iκκβ) levels or nitrate oxide-4 (NOX4) expression and by increasing the levels of antioxidants enzymes like superoxide dismutase (SOD), catalase (CAT) glutathione reductase (GRx) and glutathione peroxidase(GPx). Besides these activities, many beneficial effects in ischemic heart diseases were also observed, such as the maintenance of the ventricular function as close as possible to normal, and the prevention of infarcted area extension. In this context, this review intends to present the actual knowledge of grape pomace’s potential antioxidant and anti-inflammatory activity in ischemic heart disease, knowledge gathered from existing in vitro and in vivo studies focused on this.

The stilbene derivative resveratrol (3,5,4′-trihydroxy-stilbene; RESV) has become the subject of interest of many researchers and the pharmaceutical industries due to its well-acclaimed beneficial biological activities. Although earlier research tended to focus on the effects of RESV on cardiovascular disorders, many other studies have described the beneficial effects of RESV in the areas of cancer chemoprevention and inflammation and interest of researchers on this compound is still increasing. It is now well accepted that the effect of RESV is not just due to its so called “antioxidant” activity but mainly (if not only) because of the ability of this compound to trigger cell signaling pathways and gene expression involved in cellular defense systems. Many “in vitro” studies on RESV did not take into account that although its oral absorption is about 75% it undergoes rapid metabolism and the concentration in the blood stream is almost undetectable. For this reason interest in the topical usage of RESV by cosmeceutical skin care brands has exponentially increased in the last decade reporting in general very promising results on its beneficial effect in protecting the skin from outdoor insults, but there is still some controversy on its topical usage mainly surrounding the concentration used. Therefore, more basic research on the topical application of RESV should be performed to better understand the way it prevents cutaneous damage and whether it could be recommended as a preventive skin aging agent for all skin insults.