The Ultraviolet Absorption of Vitamin B _c and Xanthopterin

Pharmaceuticals and Natural Drugs

“…The color thus formed can be examined in a suitable colorimeter. Bloom et al (27) have further discussed the assay of folic acid.…”

The Chemistry of the Pteridines.

“…The ultraviolet and visible light absorption of the pteridines has been thoroughly studied (7,13,22,39,49,71,82) and strongly resembles that of the flavines and alloxazines (7,50). Simple derivatives carrying functional substituents only in the 2-and 6-positions are yellow; those substituted in the pyrazine ring may be yellow or colorless according to the number and position of the substituents.…”

“…In addition to retaining water of crystallization tenaciously, they burn with difficulty in both carbon-hydrogen and Dumas nitrogen analyses. To point out that in spite of continuing work since 1925, the correct molecular formulas of the three most important pterins 7 No inconsiderable part was the collection of enough insects to insure reasonable quantities of material with which to work. A large number of cabbage butterflies were collected by school children during the summers of 1930-32 under the supervision of their teachers at the inducement of the Bavarian Ministry of Education, and a considerable number were also obtained from the Freiburg region.…”

Relation of Bacteria to Vitamins and Other Growth Factors

“…The L. casei factor appears to contain a free amino group as it becomes inactive on treatment with nitrous acid, on acetylation, or on benzoylation. L. casei factor and folic acid have been related to xanthopterin because of a similarity in ultraviolet absorption spectra (Stokstad 400, Hutchings et al, 125, Mitchell, 245, and Bloom et al, 36) and hence it seems probable that the several factors contain a unit structure similar to that of xanthopterin. Additional evidence of a relationship to xanthopterin is found in certain common physiological properties: cure of fish anemia, relation to one another in synthesis or destruction by rat liver, and inhibition of synthesis by Aerobacter aerogenes (Wright et al, 465, 467-469).…”