PRENYL BIBENZYLS FROM THE LIVERWORTS RADULA PERROTTETII AND RADULA COMPLANATA

Article abstract of DOI:10.1016/0031-9422(91)84130-K

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 1H and 13C 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 their 1H and 13C 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 1H and 13C NMR spectral data with those of radulanins A and H.The structures of the previously reported radulanins A and H isolated from R. complanata are confirmed as correct by difference NOE.Some prenyl-containing bibenzyls showed 5-lipoxygenase and calmodulin inhibitory activity and vasopressin antagonist activity.R. perrottetii is a chemically isolated species in the Radulaceae.