Chemical and chemotaxonomical studies on filices. LI. Chemical studies on the constituents of Costa Rican ferns. 3.

The constituents of three Costa Rican ferns of Pteridaceae were investigated. From Jamesonia scammanae A. TRYON, a new pterosin-type compound (I), named jamesonin, along with two pterosin derivatives and six ent-kaurane-type diterpene derivatives were isolated, and I was established as (2R, 3R)-3-hydroxy-6-(2-hydroxyethyl)-2, 7-bishydroxymethyl-2, 5-dimethylindan-1-one by spectroscopic methods. From Dicksonia gigantea KARST., two known pterosin derivatives were isolated, and from Paesia anfractuosa C. CHR., two flavonol glycosides.