Diterpenes of Cheilanthes argentea, a Fern from Asia

Abstract

Abstract The major components o f the white exudate or farina from the abaxial side of fronds of the fern Cheilanthes argentea are the diterpenoid acids ent-8(17),E-13-labdadien-15-oic acid and its 3 R-hydroxy derivative. This is the first report of the first o f these compounds as a natural product. Both are highly crystalline. Plants from the Asian mainland and Japan contain mostly the first compound whereas plants from Taiwan contain mostly the 3 R-hydroxy derivative. Thus, there are at least two distinct chemical races of the species Cheilanthes argentea.