There is an ongoing debate about the right amount of human sun exposure in order to maximize the health bene- ?ts arising from the photosynthesis of vitamin D in epidermal skin cells. The speci?c conditions of skin exposure to ultraviolet radiation lead to varying amounts of produced vitamin D photo isomers. Wavelength, intensity, and duration of light exposure, as well as skin pigmentation or the presence of sunscreen have signi?cant in?uence on the composition and amount of vitamin D photo isomers produced by irradiation. In order to give recommen- dations of healthy sun exposure, public health policy is in dire need of a detailed understanding of the underlying molecular mechanisms. In particular, it is necessary to quantitatively understand the relationship between irradia- tion conditions and production of vitamin D photoisomers. In applying non-adiabatic ab initio molecular dynamics simulations combined with experimental femtosecond-resolved spectroscopic measurements to investigate the photo dynamics of vitamin D isomers in phospholipid bilayers, this proposal seeks to unravel the mechanisms of vitamin D photosynthesis at physiological conditions. By explicitly including the chemical environment of the membrane, our approach goes signi?cantly beyond simpli?ed gas phase and solution phase studies and can be directly compared to vitamin D photosynthesis in vivo. This combined theoretical/experimental approach is unprecedented in vitamin D research and will lead to new insights, providing a molecular picture of the processes with femtosecond resolution in time. The results of this study will signi?cantly progress the understanding of the vitamin D photosystem on a molecular level that can be used to weigh up health bene?ts of sun exposure against its risks. Furthermore, the photochemical mechanism can be put in relation to other parts of vitamin D research in order to construct a comprehensive picture, providing a solid basis for public health recommendations.
There is an ongoing debate about the right amount of human sun exposure in order to maximize the bene?cial health effects arising from the photo production of vitamin D and its photo isomers in epidermal skin cells. The speci?c conditions, such as wavelength of light, length of sun exposure, skin pigmentation, and presence of sun- screen affect the amount and ratio of the produced vitamin D photo isomers. Here, we propose to carry out real- time quantum mechanical molecular dynamics simulations combined with experimental femtosecond-resolved spectroscopic measurements to unravel the mechanistic details of vitamin D photosynthesis in the natural envi- ronment of the cellular membrane with the aim to derive a direct relationship between the irradiation conditions and the production of vitamin D photo isomers.
| Tapavicza, Enrico; Thompson, Travis; Redd, Kenneth et al. (2018) Tuning the photoreactivity of Z-hexatriene photoswitches by substituents - a non-adiabatic molecular dynamics study. Phys Chem Chem Phys 20:24807-24820 |
| Thompson, Travis; Tapavicza, Enrico (2018) First-Principles Prediction of Wavelength-Dependent Product Quantum Yields. J Phys Chem Lett 9:4758-4764 |
