Syntheses and pharmacological activities of the derivatives of furanosesquiterpenes from Ligularia virgaurea.

Four benzofuranosesquiterpenes, 1-hydroxy-2-(3'-pentenyl)-3,7-dimethylbenzofuran (1), 1-hydroxy-2-(3'-pentenyl)-3,7-dimethylbenzofuran (2), cacalol (13), and 1,2-dehydrocacalohastin ( 14) were isolated from the rhizomes of Ligularia virgaurea (Compositae). A lipophilic group and an aqueous-favoring group were introduced to the compounds 1 and 13 to afford twelve new derivatives. Their structures were elucidated by spectroscopic methods. The results of the pharmacological test indicated that some of them can block Ca (++) influx by occupying binding sites of dihydropyridine.