Comparative evaluation of growth inhibitory effect of stereoisomers of fucoxanthin in human cancer cell lines

Abstract

Inhibitory effects of geometrical isomers of fucoxanthin – characteristic carotenoid of brown seaweeds – on the growth of various cancer cells and on human leukemia (HL-60), colon cancer (Caco-2) and prostate cancer cells (PC-3 and LNCap) were comparatively evaluated. All- trans fucoxanthin was the major geometrical isomer (∼88%) found in the fresh brown seaweed ( Undaria pinnatifida) apart from a small amount of 13- cis and 13′- cis isomers (∼9%). Incubation of the fucoxanthin isomeric mixtures, all- trans fucoxanthin with a small amount of 13- cis and 13′- cis isomers, produced 9′- cis isomer (5%) and increased the contents of 13- cis and 13′- cis isomers (27%). The antiproliferative effect of the mixture of 13- cis and 13′- cis isomers was stronger than all other geometrical isomers evaluated in the study. The inhibition of growth of HL-60 cells was higher in case of 13′- cis isomer followed by 13- cis and all- trans isomers. The potent inhibitory effect of 13- cis and 13′- cis fucoxanthin on HL-60 cells and Caco-2 cells could possibly be due to their higher apoptosis-inducing activity.