Abstract
(I) The various conditions for detemining vitamin D by thin-layer chromatography in Lentinus ededes were studied and the appropriate conditions were described. (2) The vitamin D contents of commerical dried fungus preparations were found to be in the range of 19 to 100 I.U./g of vitamin D. The contents less than 40 I.U./g could hardly be determined owing to the contaminations of much noncalciferol compounds as compared with those of vitamin D. The commercial fresh fungus contained the vitamin in the order of 20 I.U. per g dry weight. (3) After irradiation of the slices of the fungus with the "Erythemal Fluorescent Lamp", the content of viamin D increased with the time of irradiation. The content of the vitamin rose from 100 I.U./g before irradiation to 3000 I.U./g after irradiation for 120 minutes. (4) After irradiation of the under surface of the fungus with "Hitachi Mercury Lamp" at a distance of 10 cm, the vitamin rose from 10 to 50μg/g in 60 minutes and those of pre-D from 10 to 30 μg/g, whereby the ratio of pre-D to the sum of vitamin D and pre-D rose to 37 per cent in 60 minutes.
