Does squalene alter the antioxidant potential of astaxanthin and fucoxanthinol? In vitro evidence in RAW 264.7 cells, a murine macrophage.

Astaxanthin (Ax) and fucoxanthin/fucoxanthinol (FuOH) are marine xanthophylls exhibiting anti-oxidant effects. Squalene (SQ) is a triterpenoid and is a precursor of sterols. This study aimed to determine if SQ can improve the effect of Ax/FuOH on lipid peroxidation. RAW 264.7 cells were treated with different concentrations of Ax, FuOH and SQ and corresponding rate of cell survival was noted. In addition,combination groups - Ax + SQ and FuOH + SQ- were also run. Cells treated with Ax, FuOH, SQ, Ax + SQ and FuOH + SQ were stimulated with lipopolysaccharide and lipid hydroperoxides were estimated. Results showed that 5 μM Ax, 2 μM FuOH and 10 μM SQ supported cell survival. In presence of SQ, cell viability improved for higher concentrations of FuOH (5, 10 μM). Lipid hydroperoxides were supressed by Ax, FuOH, Ax + SQ and FUOH +SQ and were significantly lower in Ax + SQ, indicating the synergistic effect of Ax and SQ. To conclude, combination of Ax with SQ enhances its ability to supress lipid peroxidation while with FuOH, SQ attenuates the toxic effect at higher doses. Moreover, this is the first time that the combined effect of SQ and carotenoids has been studied and reported.