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Masahiro Kono, Patrice Goletz, Anne M Hanneken; Flavonoid effects on rod and cone opsins. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4520.
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© ARVO (1962-2015); The Authors (2016-present)
Flavonoid supplementation has been implicated in improved vision and/or protection against retinal degeneration. One explanation has been linked to antioxidant properties of flavonoids. More recent studies have suggested that there could be allosteric effects or some kind of effect on dark adaptation. The purpose of this study was to study the effects of several flavonoids on rod and cone opsins’ ability to activate transducin.
Rod and cone opsins were expressed in COS cells, and membrane preparations from those cells were isolated. We tested four flavonoids (eriodictyol, fisetin, quercetin, and myricetin) as ligands for S-cone, M-cone, and rod opsins by measuring their effects on transducin activation using a radioactive filter binding assay. Using crystal structures of rhodopsin as templates, we modeled the docking of these flavonoids into the opsin binding pockets with Autodock Vina.
Flavonoids have different effects on opsin activity depending flavonoid and opsin type. Eriodictyol and quercetin acted as agonists to rod opsin; whereas, fisetin and myricetin had no effect. All four flavonoids acted as inverse agonists to the M-cone opsin. On the other hand, eriodictyol, quercetin, and myricetin are agonists for S-cone opsins; whereas, fisetin had no effect. These results are reminiscent to how beta ionone effects the different opsins’ ability to activate transducin. Molecular modeling results further suggest the feasibility of the flavonoids to occupy the retinal binding pocket of rod and cone opsins.
Non-retinoids can interact with rod and cone opsins to effect structural changes that lead to activation or deactivation of opsins. Thus, while the rod and cone opsins are similar, they are not identical. Furthermore, differences between the M- and S-cone opsins are evident.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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