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-1-(3', 4'-dihydroxy)-phenyl-1, 2-dihydronaphthalene (1) and 3-carboxy-6,7-dihydroxy-1-(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.