Light-dependent synthesis of cholecalciferol in a green plant

Provitamins and vitamins D2 and D3 in Cladina spp. over a latitudinal gradient: possible correlation with UV levels

“…In the grass, Trisetum flavescens [9], as well as in tomato leaves [18,19], vitamin D 3 is formed only under UV-irradiation, which suggests a similar mechanism of vitamin D 3 biosynthesis in plants as that in the vertebrate and human skin [13]. There is a positive correlation between the vitamin D 3 content of C. arbuscula and the calculated UV-B exposure at the place and day of sample collection ( Fig.…”

“…In S. malacoxylon, vitamin D 3 may be hydroxylated by a similar pathway as in animals [12]. It has been suggested that the synthesis of vitamin D in plants is similar to the photolytic reactions occuring in the skin of vertebrates [9,13], but in some plants or plant cells vitamin D 3 can be formed also without the action of ultraviolet-B radiation ( [14] and own results to be published separately). The biological functions of vitamin D 3 and its metabolites in plants remain unclear.…”

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“…Often as much provitamin D3 and vitamin D3 are produced (Zucker et al 1980, Prema & Raghuramulu 1996. Even 1,25-dihydroxy vitamin D3 has been found in plants (Napoli et al 1977), as well as a glycoside of this compound, sometimes at concentrations high enough to poison grazing animals (Wasserman et al 1976).…”

“…Plants produce provitamins D, vitamins D and related compounds in their leaves (Napoli et al 1977;Wasserman 1975;Prema & Raghuramulu 1994Zucker et al 1980;Rambeck et al 1981;Horst et al 1984). …”

A Vitamin D3 Steroid Hormone in the Calcinogenic Grass Trisetum flavescens

“…Most of these symptoms are known from hypervitaminosis D and it was therefore not surprising when a strong antirachitic activity of the plant was demonstrated [10][11][12], From a diethyl ether extract of Trisetum flavescens we isolated a fraction showing a strong vitamin Dlike activity in several bioassays. A gas chromato graphic-mass spectrometric analysis of the purified extract revealed that the calcinogenic plant actually contains vitamin D3, the "animal vitamin D " [13], at a concentration of about 0.1 ppm [14], In analogy to the formation of the vitamin in the skin of verte brates, vitamin D3 in T. flavescens is synthesized only under the influence of UV light [15], Part of the vitamin D3 is present as an ester, but neither the vitamin itself nor the esterified form would be cal cinogenic at this concentration [16,17], Peterlik et al [18] were the first to report a vitamin D-like substance in Trisetum flavescens that requires no further metabolism in order to exert its effects. Active compounds are l,25(O H )2D3, l,25(OH)2D2, la(O H )D 3 or structural analogs.…”