10 ヤスデゴケ属(Frullania)の生理活性セスキテルペン

抄録

Some occupational allergies (contact dematitis) associated with the handling of European woods are caused by epiphytic Bryophytes, namely Hepaticae such as Frullania. We have previously described the isolation and the synthesis of (-)-frullanolide (1), a new sesquiterpene lactone possessing allergenic properties from Frullania tamarisci. Patients sensitive to crude extracts of Frullania are usually highly sensitive to pure frullanolide. However, there are a few exception, which led us to search for other components of Frullania extracts, and we describe now the isolation of seven further new lactones of eudesmane and eremophilane series (Ent-1, Ent-9, Ent-15, 11, 12, 13 and 14) possessing the unusual 7-α configuration from Frullania dilatata and β-cyclo-costunolide (17), a new 4-β-OH(ax)eudesmanolide (19) and a new sesquiterpene aldehyde (21) possessing the 7-β configuration from F. tamarisci subsp. obscura. Twelve patients sensitive to Frullania were tested to the new lactones isolated from F. dilatata. All our patients sensitive to Frullania are sensitive to at least one of the α-methylene-T-butyro lactone. It is noteworthy that (1) in F. tamarisci and (Ent-1) in F. dilatata are the major components, however 4-β-OH eudesmanolide (19) is the major one in F. tamarisci subsp. obscura and cis-lactones have not been detected from this species. The biogenesis of the present sesquiterpene lactones may be rationalized by assuming the strightworword acid-catalized cyclization of costunolide type (18) and of inunolide type (23) precursor.