Accumulation of Caffeoyl-D-quinic Acids and Catechins in Plums Affected by the Fungus Taphrina pruni

Claus T. Fuchs and Gerhard Spiteller Institut für Organische Chemie I, Universität Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany Z. Naturforsch. 53c, 799-805 (1998); received February 20/April 16, 1998 Taphrina pruni, Plums, Catechins, Caffeoyl-D-quinic Acids, Photometric Determination Plums (Prunus domestica) affected by the fungus Taphrina pruni and healthy ones were harvested in intervals of about four days. Photometric comparison of their methanolic ex­ tracts proved that infected fruits contained ten times more compounds with phenolic hy­ droxyl groups. Further structure elucidation and quantification of these phenolic differences by gas chromatography and gas chromatography / mass spectrometry revealed that the content of caffeoyl-D-quinic acid isomers and (+)-catechin had changed: The amount of chlorogenic acid and its isomers was increased in infected fruits about 15 times compared to non­ affected ones. Contrary, (+)-catechin content was decreased. Additional photometric assays demonstrated that (+)-catechin reduction is accompanied by a corresponding increase of proanthocyanidins in infected fruits. All the compounds identified in infected plums in increased concentrations had a common structural feature: they were o-diphenols. After oxi­ dation to corresponding o-quinones they are able to add to substances with active hydrogen atoms, e.g. fungal enzymes. Consequently, the accumulation of a high concentration of odiphenols may be a defence response directed towards fungal enzymes.