Structures of Compounds with Antigonadotropic Activity Obtained byin vitroOxidation of Caffeic Acid

Abstract
Two new cyclolignan derivatives were isolated by HPLC from the mixture of substances obtained after oxidation of caffeic acid with KMnO4. Their structures were elucidated by spectroscopic methods as 2,3-dicarboxy-6,7-dihydroxy-l-(3′,4′-dihydroxy)-phenyl-1,2-dihydronaphthalene (1) and 3-carboxy-6,7-dihydroxy-l-(3′,4′-dihydroxy)-phenylnaphthalene (2). Compounds 1 and 2 exhibit antigonadotropic activity as do the extracts of crude drugs of Lycopus europaeus and Lithospermum officinale after oxidation by plant enzymes.