Is the action spectrum for the UV-induced production of previtamin D3 in human skin correct?

Norval, Mary; Björn, Lars Olof; Gruijl, Frank R. de

doi:10.1039/b9pp00012g

Cited by 87 publications

(90 citation statements)

References 50 publications

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“…(Brooke-Wavell et al, 2008, Macfarlane et al, 2005. Solar radiation is composed of 90-99% UVA and 1-10% UVB (Norval et al, 2010), when it reaches the highest point at noon at the equator (Thieden et. al., 2008).…”

Section: Introductionmentioning

confidence: 99%

Vitamin D production in UK Caucasian and South Asian women following UVR exposure

Hakim

Hart

McCabe

et al. 2016

The Journal of Steroid Biochemistry and Molecular Biology

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Section: Introductionmentioning

confidence: 99%

Vitamin D production in UK Caucasian and South Asian women following UVR exposure

Hakim

Hart

McCabe

et al. 2016

The Journal of Steroid Biochemistry and Molecular Biology

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“…There is significant debate on the pre-vitamin D synthesis action spectrum (Norval et al 2009), however at the time of the data modelling this was the most appropriate weighting. This is the first time that a study has investigated the population level The cross-sectional analysis had several strengths and weaknesses.…”

Section: Natural Differences In Ambient Uvmentioning

confidence: 99%

Coastal climate is associated with elevated solar irradiance and higher 25(OH)D level

Cherrie

Wheeler

White

et al. 2015

Environment International

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Introduction There is evidence that populations living close to the coast have improved health and wellbeing. Coastal environments are linked to promotion of physical activity through provision of safe, opportune, aesthetic and accessible spaces for recreation. Exposure to coastal environments may also reduce stress and induce positive mood. In addition to these processes we hypothesised that coastal climate may influence the vitamin D status of residents and thus partly explain benefits to health. Materials and MethodsEcological and cross-sectional analyses were designed to elucidate the connection between coastal residence and vitamin D status. We divided residential data, from developed land use areas and the Lower Super Output Areas of the 1958 Birth Cohort participants, into the following coastal bands: <1km, 1-5km, 5-20km, 20-50km and over 50km. In the ecological analysis we used a multiple regression model to describe the relationship between UVvitd and coastal proximity adjusted for latitude. Subsequently, using the residential information of the participants of the 1958 Birth Cohort we developed a multiple regression model to understand the relationship between serum 25(OH)D (a marker of vitamin D status) and coastal proximity adjusted for several factors related to vitamin D status (e.g. diet, outdoor activity). ResultsWe found that coastal proximity was associated with solar irradiance; a 99.6 (96.1-103.3) J/m2/day regression coefficient was observed for settlements <1 km from the coast compared with those above 50 km. This relationship was modified by latitude with lower latitude exhibiting a greater effect. Individuals living in the <1 km coastal category had on average a 4 nmol/l higher vitamin D status compared to those living inland. ConclusionGeographic location in the UK may influence human biochemistry and health outcomes due to environmental factors. This can provide benefits in terms of vitamin D status but may also pose a risk due to higher skin cancer rates. We provide further evidence in support of the claim that coastal environments can provide opportunities for health and wellbeing. Exposure to coastal environments may also reduce stress and induce positive mood. 29In addition to these processes we hypothesised that coastal climate may influence 30 the vitamin D status of residents and thus partly explain benefits to health. 31 Materials and Methods 32Ecological and cross-sectional analyses were designed to elucidate the connection Results 43We found that coastal proximity was associated with solar irradiance; a 99.6 (96.1-

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“…However, since the regulative mechanism only works under irradiation of the spectrum of a black body emitter at the temperature of the sun, it is questionable to which extent the monochromatically derived action spectrum is capable to explain the photoequilibrium under the solar spectrum. At present, there is an ongoing dispute about the validity of several measured action spectra in the literature, 14 and a recent study has found that the action spectra vary between previously irradiated and unexposed skin sam-ples. 15 To date, the exact regulative mechanism of Vita photo production is still not well understood and no accurate quantitative predictions can be made.…”

Section: Introductionmentioning

confidence: 99%

The role of tachysterol in vitamin D photosynthesis – a non-adiabatic molecular dynamics study

Cisneros

Thompson

Baluyot

et al. 2017

Phys. Chem. Chem. Phys.

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To investigate the role of tachysterol in the photophysical/photochemical regulation of vitamin D photosynthesis, we studied its electronic absorption properties and excited state dynamics using time-dependent density functional theory (TDDFT), second-order approximate coupled cluster theory (CC2), and non-adiabatic surface hopping molecular dynamics in the gas phase. In excellent agreement with experiments, the simulated electronic spectrum shows a broad absorption band with a remarkably higher extinction coefficient than the other vitamin D photoisomers provitamin D, lumisterol, and previtamin D. The broad band arises from the spectral overlap of four different ground state rotamers. After photoexcitation, the first excited singlet state (S 1 ) decays with a lifetime of 882 fs. The S 1 dynamics is characterized by a strong twisting of the central double bond. In 96% of all trajectories this is followed by unreactive relaxation to the ground state near a conical intersection. The double-bond twisting in the chemically unreactive trajectories induces a strong interconversion between the different rotamers. In 2.3 % of the trajectories we observed [1,5]-sigmatropic hydrogen shift forming the partly deconjugated toxisterol D1. 1.4 % previtamin D formation is observed via hula-twist double bond isomerization. In both reaction channels, we find a strong dependence between photoreactivity and dihedral angle conformation: hydrogen shift only occurs in cEc and cEt rotamers and double bond isomerization occurs mainly in cEc rotamers. Hence, our study confirms the previously formed hypothesis that cEc rotamers are more prone to previtamin D formation than other isomers. In addition, we also observe the formation of a cyclobutene-toxisterol in the hot ground state in 3 trajectories (0.7 %).Due to its large extinction coefficient and mostly unreactive behavior, tachysterol acts mainly as a sun shield suppressing previtamin D formation. Tachysterol shows stronger toxisterol formation than previtamin D and can thus be seen as the major degradation route of vitamin D. Absorption of low energy ultraviolet light by the cEc rotamer can lead to previtamin D formation. In addition the cyclobutene-toxisterol, which possibly reacts thermally to previtamin D, is also preferably formed at long 2 wavelengths. These two mechanisms are consistent with the wavelength dependent photochemistry found in experiments. Our study reinforces a recent hypothesis that tachysterol constitutes a source of previtamin D when only low energy ultraviolet light is available, as it is the case in winter or in the morning and evening hours of the day.3

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Is the action spectrum for the UV-induced production of previtamin D3 in human skin correct?

Cited by 87 publications

References 50 publications

Vitamin D production in UK Caucasian and South Asian women following UVR exposure

Vitamin D production in UK Caucasian and South Asian women following UVR exposure

Coastal climate is associated with elevated solar irradiance and higher 25(OH)D level

The role of tachysterol in vitamin D photosynthesis – a non-adiabatic molecular dynamics study

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