TY - JOUR T1 - A Comparison of Methods For Quantifying Oligomeric Proanthocyanidins From Grape Seed Extracts JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. SP - 383 LP - 389 DO - 10.5344/ajev.2000.51.4.383 VL - 51 IS - 4 AU - Andrew L. Waterhouse AU - Steve Ignelzi AU - Joseph R. Shirley Y1 - 2000/01/01 UR - http://www.ajevonline.org/content/51/4/383.abstract N2 - Grape seed extract (GSE) has become popular in recent years as a nutritional supplement that possesses antioxidant activity. These extracts contain a heterogeneous mixture of monomers, oligomers, and polymers composed of proanthocyanidin (or flavan-3-ol) subunits. The common colorimetric methods for analyzing the procyanidin concentration and/or composition of grape seed extracts and products containing it can give only crude information on the distribution of the sizes of the components. A normal phase HPLC method has proven to be very applicable to analyzing grape seed extract material and products thereof, and monomer, oligomer (2-7 subunits) and polymeric (8-24 subunits, and ∼24+ subunits) fractions can be discriminated. Values ranged from 5% to 30% for monomers, 17% to 63% oliogomers, 11% to 39% polymers and 2% to 50% for the large (24+) polymers. When specific attributes can be defined for particular size fractions, this method can provide the information needed to compare different samples for their relative potential effect. ER -