INHIBITION OF GROWTH AND INDUCTION OF DIFFERENTIATION OF PROMYELOCYTIC LEUKEMIA (HL-60) BY CAROTENOIDS FROM CROCUS-SATIVUS L

The effects of carotenoids of Crocus sativus L. (saffron) on cell prol iferation and differentiation of HL-60 cells have been studied and com pared with those of all-trans retinoic acid. Our results demonstrated that the doses inducing 50% inhibition of cell growth were 0.12 mu M f or all-trans retinoic acid (ATRA) and for carotenoids of saffron 0.8 m u M for dimethylcrocetin (DMCRT), 2 mu M for crocetin CRT and 2 mu M f or crocins (CRCs). At 5 mu M, all these compounds induced differentiat ion of HL-60 cells, at 85% for ATRA, 70% for DMCRT, 50% for CRT and 48 % for CRCs. In these experiments, leukemic cells were cultured for 5 d ays in the absence or in the presence of up to 5 mu M ATRA or seminatu ral and natural carotenoids. Since retinoids have a potential applicat ion as chemopreventive agents in humans, their toxicity as an importan t limiting factor for their use in treatment should be extensively exp lored. The seminatural (DMCRT and CRT) and natural carotenoids (CRCs) of Crocus sativus L. are not provitamin A precursors and could therefo re be less toxic than retinoids, even at high doses.