DITERPENES

PURPOSE: To obtain new diterpenes isolated from Stellerae radix as a specific kind of herb crude drug, expressed by a specific formula, having potent anti- AIDS virus action, thus useful as an anti-AIDS virus agent. CONSTITUTION: The subject new compounds are expressed by formula I (R1 is CH2 CO or of formula II; R2 is CH3 CO, CH3 (CH2 )8 CO or of formula II) and obtained by the following process: an ester extracted by a lower alcohol from the ground and/or underground portion(s) of Stellerae radix as a kind of herb crud drug is subjected to silica gel chromatography, and the eluted part obtained using a hexane-ethyl acetate (1:4) mixed solvent is subjected to reversed phase chromatography and methanol/water treatment to obtain gnidimacrin, stelleramacrin and simplexin, and the fraction with high anti-AIDS virus activity containing the above substances is purified through open column chromatography, and the resultant diterpenes are further purified through dispensing thin-layer chromatography.