Provitamins and vitamins D₂and D₃in Cladina spp. over a latitudinal gradient: possible correlation with UV levels

Provitamin D2, vitamin D2 and vitamin D3 were identified in the thallus of a lichen species, Cladina arbuscula (Wallr.) Hale and W.L. Culb. The identification of vitamin D3 was supported by: (1) co-chromatography in both reverse and straight phase HPLC (high performance liquid chromatography), (2) ultraviolet absorption spectrum, and (3) molecular ion peaks demonstrated by ESI (electrospray ionisation) mass spectrometry. The contents of vitamin D3 range from 0.67 to 2.04 μg g⁻¹ dry matter in the thalli of C. arbuscula specimens grown under different natural conditions, while provitamin D3 could not be detected. The ranges for provitamin D2 and vitamin D2 were 89-146 and 0.22-0.55 μg g⁻¹ dry matter, respectively, while the contents of provitamin D3 were below the detection limit (0.01 microg g(-1) dry matter). When C. arbuscula thalli collected at different latitudes from northern Finland to Greece were compared, a positive correlation of vitamin D2 and D3 contents with modelled UV-B radiation at the collection sites was found. A single sample of C. rangiferina from northern Finland gave much higher values for the vitamins. A possible reason could be the lower content of UV-B absorbing pigment in the latter species.

An improved procedure for the isolation of suprasterol2 I and II from a photochemical reaction mixture of ergocalciferol (vitamin D2)

An improved procedure for the isolateion suprasterol2 I and II from a photochemical reaction mixture of ergocalciferol (vitamin D2) and their spectral data are described in this paper. When a solution of ergocalciferol in ethanol was irradiated by UV light from a high-pressure mercury lamp, the reaction mixture gave six spots, including suprasterol2 I and II, on the thin-layer chromatogram, while the peaks corresponding to pyro-D2, isopyro-D2,5,b-trans-D2, suprasterol 2 I and II were observed in the gas chromatogram obtained from a capillary column GLC (Suprasterol2 I and II were main peaks). After purifying the mixture by column chromatography on silica gel containing 12% alumina as an absorbent, two main fractins were isolated. The data of their spectra, TLC and GLC showed that the former fraction was suprasterol2 II while the latter was suprasterol2 I and that the both fractions contained the respective compound only. Both suprasterol2 were crystallized as the 3,5-dinitro-benzoates.