PURPOSE: An antitumor agent comprising a partially novel diterpenoide selected from O-methylshikoccin, epoxyshikoccin, O-methyl-epoxyshikoccin, shikoccidin, deoxyshikoccidin, and a specific shikoccin derivative, as an active ingredient.
CONSTITUTION: An antitumor agent comprising one or more diterpenoides selected from O-methylshikoccin, epoxyshikoccin, a novel O-methylepoxyshikoccin shown by the formula I (Ac is COCH3; Me is CH3), shikoccidin, deoxyshikoccidin, and a novel shikoccin derivative shown by the formula II, as an active ingredient. The above-mentioned compounds other than the compound shown by the formula II are obtained by concentrating ether extracts of the dry aerial parts of Raabdosia shikokiana (Makino) Hara var. occidentalis, washing it with water, removing saccharides, followed by separation through column chromatography. The compound shown by the formula II is obtained easily by oxidizing a shikoccin shown by the formula III, another component of the extracts, with chromic acid, etc. by a conventional procedure.
FUJI KAORU
NOIDE MANABU
ITOU NOZOMI
