Anti-neoplastic effect of halocynthiaxanthin, a metabolite of fucoxanthin.

We have reported that fucoxanthin, a natural carotenoid, inhibited the growth of human neuroblastoma GOTO cells. In the present study, we show that a metabolite of fucoxanthin, halocynthiaxanthin, which is isolated from sea squirt Halocynthia roretzi, has a more potent inhibitory effect. Halocynthiaxanthin (5 micrograms/ml) caused complete suppression of GOTO cell proliferation, whereas fucoxanthin reduced the growth rate by only 88.8% compared with the control, at day 2 after the drug treatment. Furthermore, halocynthiaxanthin also inhibited the growth of other human malignant tumor cells. Thus halocynthiaxanthin seems to be a promising anti-neoplastic agent.