Hymenosides A-F, six new hemiterpene glucosides from the Japanese fern Hymenophyllum barbatum

In the course of investigation of the bitter-tasting substances of the Japa nese fern Hymenophyllum barbatum belonging to the family Hymenophyllaceae, six new hemiterpene glucosides called hymenosides A-F (1-6) have been isola ted from the methanol extract, together with an acyclic bis-bibenzyl deriva tive, perrottetin H. This paper deals with the structure elucidation of the newly isolated glucosides.