Abstract: A process for extracting essentially oligomeric catechin polyphenols from a potentilla plant, including the steps: treating at least part of the plant with a polar organic solvent to form a first extract, evaporating the first extract to dryness at a temperature of not more than 60.degree. C. to form an evaporation residue, adding water to the evaporation residue to form an aqueous solution, exhaustively extracting the solution with a water-immiscible solvent capable of dissolving oligomeric catechin polyphenols to form an organic solution, evaporating the organic solution to dryness at a temperature of not more than 60.degree. C. to form a second extract of essentially oligomeric catechin polyphenols. The second extract can be used as a compound having a free radical-scavenging action and/or action against UV rays.

Abstract: Polyphenol derivative compositions including oligomer or polymer esters containing N+2 monomer moieties, whose monomer moieties correspond to the following formula ##STR1## in which N is a number from 0 to 100, A represents a group --OR, a hydrogen atom or a substituent R, at least a majority of the substituents R represent a group --COR.sub.1, R.sub.1 is a saturated or unsaturated, linear or branched alkyl radical of at least two carbon atoms, or an aryl, aralkyl or aralkylene radical, a remainder of the substituents R is a hydrogen atom, an alkyl group, an acyl group --CO--C.sub.6 H.sub.2 --(OH).sub.3, a monosaccharide or a polysaccharide, and n.sub.1 and n.sub.2, which are identical to or different from each other, are numbers from 1 to 3, corresponding to the number of substitutions on a ring, and the diastereoisomers and the regioisomers of said monomer moieties, whereby the monomer moieties are connected by carbon--carbon bonds or by ether bridges between the rings which make up a flavan ring system.

Abstract: Process for esterifying a polyphenolic oligomer extract of plant origin by the action of an acid chloride, the compositions obtained by this process and their use in human therapy or in cosmetics are described. The extract is placed in a liquid medium which is not a solvent for the extract but which is a solvent for the ester(s) to be obtained, so as to obtain a suspension. At least one aliphatic tertiary amine of low boiling point is added to the suspension in the presence of a catalytic amount of at least one organic base other than pyridine. At least one fatty acid chloride is introduced into this mixture, the reaction mixture being stirred at a temperature below 40.degree. C. and then concentrated by evaporation in order to obtain an esterified extract.