Efeito protetor do vinho tinto contra oxidação em carne marinada e capacidade redox ativa do resveratrol em sistemas modelos

Abstract

The objective of this thesis was to evaluate and elucidate the action of red wine phenolic compounds on the oxidation reactions in marinated meat and the active redox capacity of resveratrol in model systems involving human serum protein and lactic acid bacteria. In the first study, the impact of marination with red wines produced from different grapes on oxidative stability and on the overall quality of beef (Longissimus lumborum) was evaluated during 7 days of refrigerated storage at 4 ºC and also in roasted beef. Four marking systems were conducted: Carbernet (CAB), Tempranillo (TEM) and Isabel (ISA), including a control, using water. In the steaks stored under refrigeration, it was observed that the specific phenolic components present in the wine were responsible for several bioativities. The ISA wine components protected proteins more effectively against oxidation, as well as improving the tenderness of steaks when compared to other treatments. However, CAB and TEM varieties, rich in procyanidins, were more effective against lipid oxidation. The phenolic composition and organic acid content of ISA wines may explain its antimicrobial effects against enterobacteria, while sugars may have promoted the growth of lactic acid bacteria in CAB and TEM treatments. In the steaks marinated and submitted to the cooking process it was verified that the ISA also demonstrated a greater protection capacity against the oxidation of the proteins, it was also effective in controlling the formation of volatile compounds derived from lipids, besides positive contributions were verified in the sensorial attributes two steaks. In general, the marination process with wine has brought benefits to bovine steaks, and in particular wines produced with Isabel grapes even being sensorially considered a wine of inferior quality, when compared to the wines produced with Vitis vinifera grapes can be used as functional ingredient in products meat. The second experiment evaluated the ability of a specific wine component, resveratrol (RES), to neutralize the oxidative damage caused by pathological concentrations of methylglyoxal (MGO) and glyoxal (GO) in human serum protein. Resveratrol neutralized both α-dicarbonyls by forming adducts and the antioxidant action resulted in a significant reduction of AGEs (Advanced glycation end products). However, pro-oxidant action of resveratrol was also observed, since resveratrol-α-dicarbonyl conjugates oxidized Cys34 (Tiol) and lysine, arginine and / or proline by a nucleophilic attack to SH (sulfhydryl group) and ε-NH amino) in HSA (human serum albumin). Future studies still need to be developed to further elucidate the pro-oxidative role of the RES-α-dicarbonyl conjugates as well as mechanisms of redox signaling and / or oxidative damage reflex and disease should also be considered in future studies. The third study provided an original insight into the genetic and molecular basis of Lactobacillus reuteri PL503 responses against oxidative stress induced by hydrogen peroxide (H2O2). Resveratrol (100 μM) has been shown to protect L. reuteri PL503 against plausible protein carbonylation through various mechanisms, including direct elimination of reactive oxygen species (ROS), up-regulation of the dhaT gene and promotion of the synthesis of compounds containing sulfur. Carbonylation of proteins as a reflection of oxidative damage to bacteria and their consequences, as well as the role of carbonyl proteins as signaling molecules implicated in bacterial responses to oxidative stress, need to be further investigated.