Structural determinants of the platelet agonist activity of cotton bract condensed tannin

Previous studies on the platelet agonist activity of cotton bract condensed tannin have used tannins with apparent molecular weights >10,000 Da as measured by dialysis and/or ultrafiltration. However, because tannins in cotton dust are heterogeneous in terms of molecular weight, it was important to determine if platelet agonist activity was related to polymer length. To accomplish this, aqueous extracts of cotton dust were fractionated by a series of graded Amicon ultrafiltrations and the resulting fractions were examined for tannin content and platelet agonist activity. All tannins with apparent molecular weight >1000 Da were equally potent platelet agonists while those