Über das Tachysterin

Windaus, A.; Werder, F. v.; Lüttringhaus, Arthur

doi:10.1002/jlac.19324990116

“…Authentic vitamin D3 was incubated at 80 °C, and the product formed was shown to have the same retention time as previtamin D3. The identity of tachysterol was confirmed by its faster rate of addition to maleic anhydride (Windaus et al, 1932;Verloop et al, 1957;Hanewald et al, 1968). Integrated peak areas were corrected for differences in extinction at 254 nm.…”

Section: Methodsmentioning

confidence: 93%

Photoconversion of 7-dehydrocholesterol to vitamin D3 in synthetic phospholipid bilayers

Yamamoto¹,

Borch²

1985

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The incorporation of 7-dehydrocholesterol into synthetic phospholipid bilayers altered the distribution of products after photolysis. In liposomes, the relative amounts of 7-dehydrocholesterol and lumisterol were elevated, and tachysterol was reduced from the levels observed in hexane solution. Z to E isomerization of the previtamin to tachysterol is favored in organic solvents. The inhibition of this process is evidence that an ordered lipid matrix places a new constraint on the conformation of the ring B fission product--one in which the configuration is favorable for a return to a cyclized diene. Further, rate enhancements of up to 15-fold were observed for the thermal isomerization of the previtamin to vitamin D3 in liposomes. The free energies of activation for the reaction at 25 degrees C were reduced by 1.3-1.5 kcal/mol in the bilayer environment compared to that of hexane. As this reaction involves the concerted transfer of a hydrogen via a cyclic intermediate, it provides additional evidence for membrane stabilization of an all-cis conformation of the previtamin. Photoproduct ratios were also studied for 7-dehydrocholesterol adsorbed to a variety of solid supports. That nonspecific interactions of 7-dehydrocholesterol with lipid can influence product formation may have important implications with respect to the mechanism of vitamin D3 biosynthesis.

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“…However, in 1928, Bills et al [377] reported that the material with a wavelength of 250 nm that was isolated from the irradiated mixture had little antirachitic activity. Subsequently, Windaus et al [378] as well as Laquer et al [379] obtained preparations of irradiation products of ergosterol that absorbed near 250 nm. This material was devoid of any activity.…”

Section: Photoproduction Of Suprasterols and Toxisterols In Human Ski...mentioning

confidence: 99%

Solar radiation and human health

Juzeniene

¹

,

Brekke

²

,

Dahlback

³

et al. 2011

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The Sun has played a major role in the development of life on Earth. In Western culture, people are warned against Sun exposure because of its adverse effects: erythema, photoimmunosuppression, photoageing, photocarcinogenesis, cataracts and photokeratitis. However, Sun exposure is also beneficial, since moderate doses give beneficial physiological effects: vitamin D synthesis, reduction of blood pressure and mental health. Shortage of Sun exposure may be even more dangerous to human health than excessive exposure. Avoiding Sun exposure leads to vitamin D deficiency which is associated not only with rickets and osteomalacia, but also with increased risk of cardiovascular disease, multiple sclerosis, rheumatoid arthritis, diabetes, influenza, many types of cancer and adverse pregnancy outcomes. Solar radiation induces nitric oxide release in tissue and immediate pigment darkening which certainly play important roles, although these are still unknown. Action spectra relevant for health are described. We will also review what is known about spectral and intensity variations of terrestrial solar radiation as well as its penetration through the atmosphere and into human skin and tissue.

show abstract

“…However, in 1928, Bills et al [377] reported that the material with a wavelength of 250 nm that was isolated from the irradiated mixture had little antirachitic activity. Subsequently, Windaus et al [378] as well as Laquer et al [379] obtained preparations of irradiation products of ergosterol that absorbed near 250 nm. This material was devoid of any activity.…”

Section: Photoproduction Of Suprasterols and Toxisterols In Human Skimentioning

confidence: 99%

Solar radiation and human health

Moan

¹

,

Juzeniene

²

2010

Journal of Photochemistry and Photobiology B: Biology

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The Sun has played a major role in the development of life on Earth. In Western culture, people are warned against Sun exposure because of its adverse effects: erythema, photoimmunosuppression, photoageing, photocarcinogenesis, cataracts and photokeratitis. However, Sun exposure is also beneficial, since moderate doses give beneficial physiological effects: vitamin D synthesis, reduction of blood pressure and mental health. Shortage of Sun exposure may be even more dangerous to human health than excessive exposure. Avoiding Sun exposure leads to vitamin D deficiency which is associated not only with rickets and osteomalacia, but also with increased risk of cardiovascular disease, multiple sclerosis, rheumatoid arthritis, diabetes, influenza, many types of cancer and adverse pregnancy outcomes. Solar radiation induces nitric oxide release in tissue and immediate pigment darkening which certainly play important roles, although these are still unknown. Action spectra relevant for health are described. We will also review what is known about spectral and intensity variations of terrestrial solar radiation as well as its penetration through the atmosphere and into human skin and tissue.

show abstract

Über das Tachysterin

Cited by 31 publications

References 8 publications

Photoconversion of 7-dehydrocholesterol to vitamin D3 in synthetic phospholipid bilayers

Photoconversion of 7-dehydrocholesterol to vitamin D3 in synthetic phospholipid bilayers

Solar radiation and human health

Solar radiation and human health

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