.Rapid Communication. Two New Bis-labdanic Diterpenoids from Alpinia calcarata

Abstract: Two novel bis-labdanic diterpenoids named calcaratarin G and calcaratarin H were isolated from the rhizomes of Alpinia calcarata Rosc. Their structures were elucidated to be a pair of stereoiso-mers on the basis of the spectral evidence. The 2D NMR techniques including 1H-1H COSY, HMQC, HMBC, NOESY and HRFABMS were extensively applied to establish the structures. Key words: Alpinia calcarata; bis-labdanic diterpenoids; calcaratarin G; calcaratarin H The labdanic diterpenoids are a class of typical com-pounds isolated from plants of the genus Alpinia which are used as traditional herbs in some areas of China and other countries (Jiangsu College of New Medicine, 1977). In recent years, more and more labdanic diterpenoids were isolated from the plants of Zingiberaceae, but the bis-labdanic diterpenoids are rare in plants. Only two bis-labdanic diterpenoids, an ester of labda-8 (17), 11, 13-trien-15-al-16-oic acid and isocoronarin D as well as moldenin were isolated from Hedychium coronarium (Nakatani e