fAside from the antioxidant impact of AX on membranes, AX as well as other carotenoids also changed the membrane dynamics of model membrane structures and microsomes [25,27]. The effect on membrane dynamics can be influenced by the properties of each (i) the carotenoid, and (ii) the membrane. (i) With respect to the influence of carotenoid properties, it can be identified that xanthophylls increase the order of phospholipid membrane packing, and decrease alkyl-chain motion inside the fluid phase. These effects are strongest for dipolar xanthophylls (i.e., AX), drastically weaker for monopolar xanthophylls (i.e., -cryptoxanthin), and negligible for nonpolar carotenes (i.e., -carotene) [51]. Along with carotenoid polarity, the concentration of carotenoids within the membrane may perhaps also influence the dynamics. (ii) Cell membranes are composed of a variety of lipids and several distinctive proteins, whose distribution isn’t homogeneous. Hence, even though AX slightly improved membrane rigidity in microsomes, this effect might not be ubiquitous across all biological membranes. Membranes of distinctive cell organelles have distinct lipid compositions, and characteristic regions inside membranes may coalesce specific kinds of lipids to kind defined regions called microdomains. Carotenoids might have characteristic distributions across various cellular organelles or membrane microdomains. As an example, membrane regions enriched in sphingolipids and cholesterol are named lipid rafts, which are defined as “small (1000 nm), heterogeneous, highly dynamic, sterol- and sphingolipid-enriched domains that JAK1 Inhibitor list compartmentalize cellular processes. Little rafts can at times be stabilized to kind bigger platforms via HDAC11 Inhibitor Source Protein rotein and protein ipid interactions” [52]. Lipid rafts have elevated membrane thickness at the same time as characteristic membrane dynamics, and they play very important roles in membrane protein signaling, and sorting via the secretory and endocytic pathways [52]. Normally, extremely polar xanthophylls with hydroxyl groups are not predominant in lipid rafts; rather, they may be enriched inside the fluid-phase of phospholipid model membranes that happen to be predominantly composed of unsaturated fatty acids. In contrast, low-polarity carotenes are localized in both forms of membranes: the extra ordered lipid rafts, and the much more fluid membranes are wealthy in unsaturated fatty acids. While the direct relationship involving carotenoids and their distribution in membrane microdomains continues to be unclear, some carotenoids have inhibited the translocation of significant membrane receptor proteins into lipid rafts (e.g., immunoreceptors) [53,54] or affected the function of lipid raft proteins by means of their antioxidant activity (e.g., rhodopsin) [51]. Cholesterol is yet another crucial modulator of membrane dynamics and function in lipid rafts and elsewhere. AX has been shown to interact with cholesterol by inhibiting the peroxidation of cholesterol to 7-keto-cholesterol better than other popular carotenoids [55]. We also reported that following insulin administration, AX had an acute effect within a type of lipid raft known as a caveolae, whereby AX modulated the association between an insulin receptor and its adaptor protein [56]. Although it can be unclear no matter if this effect was as a result of AX’s antioxidant activity or other components, AX acutely enhanced the insulin-dependent glucose uptake signaling via phosphatidylinositol 3-kinase (PI3K)/Protein Kinase B (Akt) activation. Simultaneously, when cytokines and cost-free fat