Pallidol

Abstract: Phenolics from grapes and wines can play a role against oxidation and development of atherosclerosis. Stilbenes have been shown to have cancer chemopreventive activity and to protect lipoproteins from oxidative damage. A method for the direct determination of stilbene oligomers (viniferin and pallidol) as well as astilbin in different types of wine using high-performance liquid chromatography with UV detection is described. In a survey of 21 commercial wines from the south of France, levels of pallidol and viniferin are reported for the first time in different types of wines. Viniferin was found to be present only in red and botrytized sweet white wines with levels between 0.1 and 1.63 mg/L; pallidol was not found in dry and sweet white wines but only in wines made by maceration with stems, with levels between 0.38 and 2.22 mg/L. Highest levels of astilbin were found in Egiodola (15.13 mg/L), Merlot (11.61 mg/L), and Cabernet Sauvignon (8.24 mg/L) for red wines and in Sauvignon (5.04 mg/L) for white varietal wines. Astilbin levels are highest for recent vintages, but pallidol is not found in older vintages. During noble rot development in Sauvignon or Semillon grapes from the Sauternes area, levels of trans-astringin, trans-resveratrol, trans-piceid, and pallidol are quite low (<0.5 mg/kg of grapes). Viniferin and astilbin levels become optimum at 2 and 30 mg/kg, respectively, during spot grape and speckle grape stages.

Abstract: Besides the already known stilbenes trans-resveratrol as well as isomeric piceids, seven novel stilbene derivatives have been isolated from a commercial Riesling wine. The newly identified compounds included the monostilbene 2,4,6-trihydroxyphenanthrene-2-O-glucoside, as well as two isomeric resveratrol-2-C-glucosides. In addition, four dimeric stilbenes, i.e., cis- and trans-e-viniferin diglucoside as well as pallidol glucoside and pallidol diglucoside, have also been obtained for the first time from Riesling wine. Keywords: Antioxidants; white wine; Riesling; resveratrol-2,4,6-trihydroxyphenanthrene 2-O-glucoside; resveratrol 2-C-glucosides; e-viniferin diglucosides; pallidol glucoside; pallidol diglucoside.