Cytotoxic effect of conjugated trienoic fatty acids on mouse tumor and human monocytic leukemia cells

The cytotoxicity of fatty acids from seed oils containing conjugated linole nic acids (CLN) was studied. Fatty acids from pomegranate, tung, and catalp a were cytotoxic to human monocytic leukemia cells at concentrations exceed ing 5 muM for pomegranate and tung and 10 muM for catalpa, but fatty acids from pot marigold oil had no effect at concentrations ranging up to 163 muM The main conjugated fatty acids of pomegranate, tung, catalpa, and pot mar igold were cis(c)9,trans(t)ll,c13-CLN (71.7%), c9,t11,t13-CLN (70.1%), t9,t 11,c13-CLN (31.3%), and t8,t10,c12-CLN (33.4%), respectively. Therefore, th e cytotoxicities of fatty acids from pomegranate, tung, and catalpa were su pposed to be due to 9,11,13-CLN isomers. To elucidate the cytotoxicity of t hese CLN, we separated each CLN isomer from the fatty acid mixtures by high -performance liquid chromatography and analyzed its cytotoxicity. The cytot oxicities of c9,t11,c13-CLN, c9,t11,t13-CLN, and t9,t11,c13-CLN were much s tronger than that of t8,t10,c12-CLN. Therefore, the higher cytotoxicity of fatty acids from pomegranate, tung, and catalpa than those from pot marigol d would be derived from the different activities of 9,11,13-CLN and 8,10,12 -CLN. Since there was little difference in the cytotoxicities of c9,lll,c13 -CLN, c9,tl l,tl 3-CLN, and t9,tl l,cl 3-CLN, it is suggested that the cis/ trans configuration of 9,11,13-CLN isomers had little effect on their cytot oxic effects. The mechanism of the cytotoxicity of the four fatty acids abo ve may involve lipid peroxidation, because the order of toxicity of the fat ty acids was consistent with their susceptibility to peroxidation in aqueou s phase. This was supported by the decrease in the cytotoxicity of the fatt y acids by addition of butylated hydroxytoluene.