The Potential Health Benefits of Phenolic Wine Constituents

Specific goals of the 1995-6 proposal were:

  1. Determine the phenolic composition of a “standard” California red wine for the purposes of health experimentation.
  2. Develop a method to measure the levels of phenolic compounds in ripe Cabernet Sauvignon grapes grown in California.
  3. Develop a method to analyze human blood plasma for many wine phenolics.

We have made significant progress towards these goals and expect to have them completed by summer’s end. Goals 2 and 3 are finished but goal 1 is incomplete to date. For Goal 1 we have completed the measurement of standard wine parameters, such as ethanol, acid and sugar levels, but have not completed the chromatographic analysis of all the phenolic constituents and this task will be complete by summer’s end. Towards Goal 2, we developed sampling methodology that reduced the very high variability previously observed in the analysis of phenolics in grape samples. In this procedure, the skins were extracted with a 1:1 methanol/water solvent for 24 hrs., while the seeds were extracted with a 1:1 acetone/water solvent mixture. These extracts showed, when analyzed for many individual compounds including catechin by HPLC, coefficients of variance of between 1.5% and 16% on triplicates. For Goal 3, we now have a procedure to analyze for the presence of multiple phenolic compounds in human plasma. This procedure involves dilution of plasma into acetonitrile, evaporation of the supernatant and re-solution before HPLC analysis. In addition to catechin, we can detect epicatechin and caffeic acid. The recovery of catechin is 88%, epicatechin 82% and caffeic acid 68%.