Provitamins and vitamins D-2 and D-3 in Cladina spp. over a latitudinal gradient: possible correlation with UV levels

Provitamin D-2, vitamin D-2 and vitamin D-3 were identified in the thallus of a lichen species, Cladina arbuscula (Wallr.) Hale and W.L. Culb. The ide ntification of vitamin D-3 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 demonstrate d by ESI (electrospray ionisation) mass spectrometry. The contents of vitam in D-3 range from 0.67 to 2.04 mug g(-1) dry matter in the thalli of C. arb uscula specimens grown under different natural conditions, while provitamin D-3 could not be detected. The ranges for provitamin D-2 and vitamin D-2 w ere 89-146 and 0.22-0.55 mug g(-1) dry matter, respectively, while the cont ents of provitamin D-3 were below the detection limit (0.01 mug dry matter) . When C. arbuscula thalli collected at different latitudes from northern F inland to Greece were compared, a positive correlation of vitamin D-2 and D -3 contents with modelled UV-B radiation at the collection sites was found. A single sample of C. rangiferina from northern Finland gave much higher v alues for the vitamins. A possible reason could be the lower content of UV- B absorbing pigment in the latter species. (C) 2001 Elsevier Science B.V. A ll rights reserved.