THE STRUCTURE OF RABDOPHYLLIN G,AN ANTITUMOR CONSTITUENT OF RABDOSIA MACROPHYLLA (Ⅱ)

The identification of four components of Rabdosia macrophylla was accomplished, three of them were shown to be identical with the known Amethystoidin A, ursolic acid and Enmenol. The 4th. is a new B-seco-ent-kaurene diterpenoid, to which the name Rabdophyllin G is suggested. Spectroscopic investigation and chemical conversion into dihydroisodonal (Ⅲ) and dihydroisodonal derivative (Ⅳ) established the structure of Rabdophyllin G. It exhibited significant inhibitory action against Ehrlich ascites carcinoma in mice.