Seven compounds are isolated from the seeds of P. nagi (Podocarpaceae) and identified as nagilactone A (I, R1 = b-OH; R2 = R3 = R4 = H), 1-deoxy-2b:3b-epoxynagilactone A (I, R1 = R4 = H; R2, R3 = b-epoxide) (II), 1-deoxy-2a-hydroxy nagilactone A (I, R1 = R3 = R4 = H, R2 = a-OH) (III), nagilactoside A (IV), sugiol, b-sitosterol and sucrose by spectral anal. and chem. methods. I is a new compound Sugiol is reported for the first time to occur in this plant. 14Oassay results show that the first 3 norditerpenoid dilactones had strong cytotoxic activity and IV is inactive. The structures of II and III are modified for studying structure-cytotoxicity relationship.

Key words: LACTONES, ANTICARCINOGEN, STRUCTURE ACTIVITY RELATIONSHIP, DITERPENES, CHEMICAL COMPOSITION, PODOCARPACEAE