A process for isolating polyphenolic antioxidants from purine-containing plant material, comprising the steps of: (a) extracting the plant material with a hydroxylic extracting liquid preferably at low temperature; (b) selectively adsorbing the extract obtained in step (a), preferably at low temperature; and (c) desorbing the adsorbed material with a hydroxylic desorbing liquid, preferably at relatively high temperature. The process is especially suitable for producing cocoa antioxidants of use in pharmaceutical, cosmetic and nutritional compositions.