Isolation and identification of previtamin D3 from the skin of rats exposed to ultraviolet irradiation

Abstract

The process of the photolytic activation of vitamin D precursor(s) in the skin was elucidated by a detailed analysis of the products formed after UV light exposure. The photolytic product isolated from the skin of rats exposed to UV irradiation was identified as previtamin D3 by several criteria including its characteristic UV absorption spectrum, mass spectrum and thermal isomerization to vitamin D3, which itself was identified also by mass spectroscopy. Vitamin D3 per se was not formed by UV irradiation.sbd.vitamin D3 arises exclusively from the thermal conversion of previtamin D3. Detectable amounts of lumisterol3 or tachysterol3 were not seen.