CHEMOSYSTEMATICS OF BRYOPHYTES .40. PRENYL BIBENZYLS FROM THE LIVERWORTS RADULA-PERROTTETII AND RADULA-COMPLANATA

A new dihydrobenzofuran and a new chromene derivatives have been isolated from the liverwort Radula perrottetii, together with the known 3,5-dihydroxy-2-(3-methyl-2-butenyl)bibenzyl, 2(R)-2-isopropenyl-6,7-dihydroxy-4-(2-phenylethyl)dihydrobenzofuran, 2,2-dimethyl-7-hydroxy-5-(2-phenylethyl)chromene, 3,5-dihydroxy-6-carbomethoxy-2-(3-methyl-2-butenyl)bibenzyl, three bis(bibenzyls) and perrottetins E, F and G. The structures of the new compounds have been characterized as 2(R)-2-isopropenyl-6-hydroxy-4-(2-phenylethyl)dihydrobenzofuran and 2,2-dimethyl-7,8-dihydroxy-5-(2-phenylethyl)chromene by H-1 and C-13 NMR spectral analysis and synthesis. The structures of the previously reported chalcone and three prenyl bibenzyls, perrottetins A, B and C, and the other two bibenzyls, isolated from R. perrottetii are revised by analysis of the H-1 and C-13 NMR data, difference NOE experiments and synthesis of their derivatives. Radulanin L, a new bibenzyl with a dihydrooxepin skeleton was isolated from R. complanata together with 2- and 4-(3-methyl-2-butenyl)-3,5-dihydroxybibenzyls and its structure elucidated by comparison of H-1 and C-13 NMR spectral data with those of radulanins A and H. The structures of the previously reported radulanins A and H isolated from F. complanata are confirmed as correct by difference NOE. Some prenyl-containing bibenzyls showed 5-lipoxygenase and calmodulin in hibitory activity and vasopressin antagonist activity. R. perrottetii is a chemically isolated species in the Radulaceae.