Does squalene alter the antioxidant potential of astaxanthin and fucoxanthinol? In vitro evidence in RAW264.7 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.