The inhibition of Caco-2 proliferation by astaxanthin from Xanthophyllomyces dendrorhous.

PURPOSE: To investigate the efficiency of natural astaxanthin that has been extracted from Xanthophyllomyces dendrorhous in inhibiting the proliferation and viability of colorectal adenocarcinoma cell line (Caco-2; colon cancer cells).

METHODOLOGY: Caco-2 cells and normal human oralkeratinocytes (NOKs) were treated with different concentrations of extracted astaxanthin, ranging from 0.075 to 10 mg ml-1 , for 24, 48 and 72 h. The number of cells was determined via MTS assay and the proliferating cells were investigated by bromodeoxyuridine (BrdU) assay.Results/Key findings. Of the Caco-2 cells, 30-50 % remained viable, while the NOKs showed 110-120 % survival when treated with 5 mg ml-1 astaxanthin. The Caco-2 cells showed distinct structural shrinkage when treated with the same concentration of astaxanthin. Fluorescent labelling of the DNA of the proliferative cells with BrdU showed a significant decrease in the number of the proliferative Caco-2 cells when the concentration of astaxanthin was increased to 5 mg ml-1 .

CONCLUSION: The natural astaxanthin from X. dendrorhous, at an appropriate concentration, is effective in terminating the viability of, or retarding the proliferative activity of, Caco-2 cells, without harmful effects on NOKs.