Ochratoxin A presence in Cabernet Sauvignon wine changes antioxidant activity in vitro and oxidative stress markers in vivo.

Ochratoxin A (OTA) is a mycotoxin found in grape products and oxidative stress has been reported as an important mechanism involved in its toxicity, classified as possible carcinogenic to humans. Conversely, phenolics are known bioactive compounds in grapes and display great antioxidant properties. However, the biological effects of the concomitant presence of phenolic compounds and OTA remains unclear. The aim of this study was to evaluate, for the first time, the effect of OTA presence in Cabernet Sauvignon wine on antioxidant activity in vitro and on oxidative stress markers in vivo. In addition, the phenolic composition of wine was evaluated by LC-DAD-MS/MS. In vitro assays were based on spectrophotometric methods, while in vivo assays were performed evaluating oxidative stress markers in the nematode Caenorhabditis elegans, an alternative model to animal testing. A total of 23 phenolic compounds were identified in the Cabernet sauvignon red wine, including the anthocyanins delphinidin-3-O-glicoside and malvidin-3-O-glicoside, the flavonol quercetin-3-O-glucuronide and the phenolic acids caffeic, verbascoside and caftaric. Trans-resveratrol and trans-piceid were the only stilbenes found in the samples. OTA presence in the red wine was accompanied by reduction in GSH content and increase in hydroxyl radical generation in vitro. The presence of OTA in wine also increased lipoperoxidation and induced overexpression of the antioxidant enzymes superoxide dismutase and catalase in vivo. This study demonstrates that OTA presence in red wine can reduce its antioxidant potential in vitro and induces oxidative stress in vivo, without affecting the phenolic compounds levels in the samples. Thus, this work provides insights into the negative effects of the presence of OTA in wine, not only by its known toxicity, but also by prejudicing the antioxidant potential of wine. It is important to be aware of these effects when developing a complete description of OTA toxicity in humans.

Composição fenólica e perfil antioxidante do suco de uva Concord / Phenolic composition and antioxidant profile of Concord grape juice

O suco de uva apresenta na constituição química uma diversidade de substâncias com ações benéficas, especialmente compostos fenólicos. O trabalho teve como objetivo analisar a composição fenólica e a capacidade antioxidante in vitro do suco de uva Concord. A atividade antioxidante foi avaliada pelos métodos de oxidação da GSH, geração do radical ABTS e ensaio da desoxirribose. A análise da composição fenólica foi realizada utilizando HPLC-DAD-MS. O suco reduziu a geração dos radicais ABTS e hidroxil bem como elevou o conteúdo de GSH. Os compostos fenólicos majoritários no suco de uva Concord foram antocianinas, ácidos fenólicos e flavonols. Os resultados obtidos demonstram o potencial antioxidante do suco da variedade Concord, possivelmente associado à sua composição fenólica.