Abstract
Purpose: :
Anecdotal clinical evidence suggests that flavonoids can improve visual function. The purpose of this study was to determine whether flavonoids modulate opsin signaling by binding to the retinal binding pocket of opsins.
Methods: :
We performed structure-based computational modeling of rod opsin to determine the binding free energies of flavonoids in the retinal binding pocket. Candidates with highly favorable binding energies were analyzed by 11-cis retinal competition studies, biochemical transducin activation assays and electrophysiological measurements of receptor sensitivity and adaptation.
Results: :
One of the candidates, eriodictyol, was tested using the methods described above. This compound competed with 11-cis retinal for binding to bovine rod opsin, and induced transducin activation in human rod and blue cone opsins and deactivation in green cone opsin. Treatment with eriodictyol desensitized bleached rods in the salamander retina.
Conclusions: :
We conclude that specific flavonoids have highly favorable binding free energies for the retinal binding pocket of rod and cone opsins, produce opsin-mediated changes in transducin activation consistent with such binding and desensitize salamander rod photoreceptors. These effects are consistent with the interaction that native retinoids have with rod and cone opsins, and suggest that these molecules may act as surrogate retinoids to modulate physiological changes of photoreceptor function.
Keywords: computational modeling • photoreceptors • nutritional factors