Caffeic acid as biomarker of red wine intake

The alcoholic component of red wine cannot be considered the unique cardioprotective factor, since red wine limits the risk for CHD more than other alcoholic beverages. Therefore, other components are implicated in the cardioprotective capacity of red wine. These are the polyphenols, which are present in red wines at levels averaging 1200 mg/liter, while only one-sixt of that concentration is found in white wines. These polyphenols comprise flavonoids and nonflavonoids. The first include anthocyanins, flavan-3-ols (e.g., catechins and their polymers known as proanthocyanidins), and, to a low extent, some flavonols (e.g., rutin, quercetin, and myricetin). Nonflavonoids are represented by hydroxybenzoates, hydroxycinnamates and trihydroxystilbenes (resveratrol isomers). All these polyphenols have free radical scavenging ability, depending on their reduction potential, and are able to break the propagation of oxidising lipids, depending on their lipophilicities. However, the detection of red wine polyphenols in humans has been scarcely investigated. Total phenol plasma concentration was recently measured with the Folin-Ciocalteau method. Unfortunately, this method is rather unspecific, as it is sensitive to nearly all oxidable compounds. Anthocyanins have been detected in human urine after red wine intake, while there is no report on the analysis in human plasma of the hydroxycinnamates caffeic acid, ferulic acid and p-coumaric acid. Recently, these acids have been identified in the urine of subjects after high intake of fruit. Extending this work, the same authors have reported on the urinary excretion of ferulic acid after a single bolus of tomatoes. The present study describes the pharmacokinetics of caffeic acid, that has been selected as a biomarker of hydroxycinnamates in plasma of subjects who received different amounts of red wine (RW) or dealcoholized red wine (DRW).