A violet-fluorescent compound produced in addition to riboflavin by a partially purified enzyme preparation obtained from the spinach was identified as 6-methyl-8-ribityl-2, 4, 7-trioxo-hexahydropteridine. This compound was shown to be directly derived from 6, 7-dimethyl-8-ribityllumazine just like riboflavin.

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The stoichiometry of the enzymatic formation of riboflavin and 6-methyl-8-ribityl-2, 4, 7-trioxo-hexahydropteridine from 6, 7-dimethyl-8-ribityllumazine was examined with a crude enzyme preparation obtained from the spinach.
1. One mole of 6-methyl-8-ribityl-2, 4, 7-trioxo-hexahydropteridine was produced from two moles of 6, 7-dimethyl-8-ribityllumazine.
2. The molar ratio of the riboflavin enzymatically produced to 6-methyl-8-ribityl-2, 4, 7-trioxo-hexahydropteridine produced varied in the presence of cysteine.
3. Formation of 6-methyl-8-ribityl-2, 4, 7-trioxo-hexahydropteridine from 6, 7-dimethyl-8-ribityllumazine was inhibited by ascorbic acid.
4. Pyruvate was incorporated enzymatically neither into riboflavin nor into 6-methyl-8-ribityl-2, 4, 7-trioxo-hexahydropteridine.

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1. The coupled oxidation of dihydrothiamine by phenolase-phenol system was demonstrated when catechol, p-cresol or hydroquinone was used as the substrate.
2. The oxidation of tyrosine by the enzyme was completely inhibited by addition of dihydrothiamine, producing no thiamine.
3. It was reconfirmed that dihydrothiamine was oxidized non-enzymatically to thiamine by a crystalline preparation of coenzyme Q₁₀, plastoquinone or menadione.
4. The stoichiometry of the oxidation reaction between dihydrothiamine and p-qinone was observed spectrophotometrically. The nature of the by-product formed by oxidation of dihydrothiamine was discussed.

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1. The urinary transaminase activity was elevated in patients with hepatitis whose serum transaminase activity was high.
2. The urinary transaminase activity was elevated in patients with high proteinuria, but there was no relation between protein quantity in the urine and the transaminase activity.
3. The urinary transaminase activity was not changed by dialysis or addition of pyridoxal phosphate.
4. Some electrolytes did not influence the GOT activity in the urine.
5. A peak of GOT and GPT activity in the urine existed in the globulin region of urine protein fractions.

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1. Additive effect of inosinic acid on the activation of diphosphothiamine in liver-pyruvate oxidase system was studied, and the increase in enzyme activity was confirmed by the addition of inosinic acid or adenosine triphosphate in vitro.
2. Further, feeding experiments were carried out with thiamine-deficient rats, and the response was studied after oral administration of inosinic acid. No effect of it on the growth curve was seen, but a marked increase of liver-pyruvate oxidase system was recognized after oral administration of thiamine plus inosinic acid.
3. The results seem to suggest that inosinic acid may contribute to the activation of diphosphothiamine in liver-pyruvate oxidase system.

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Fat-soluble riboflavin derivatives, riboflavin-2′, 3′, 4′, 5′-tetrapalmitate, -tetracaprate, -tetrabutyrate and -tetrapropionate, were synthesized by esterification of riboflavin with, fatty acid chloride or by the reaction of the vitamin with fatty acid anhydride.
Their physicochemical properties were reported.

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1. Fatty acid esters of riboflavin were hydrolyzed to the vitamin by pancreatic lipase. In the case of butyrate (R-BUT, ) the optimum pH and temperature were 7.3 and 37° respectively. Rates of hydrolysis of palmitate (R-PAL), caprate (R-CAP), R-BUT, propionate (R-PROP) and acetate (R-ACET) by this enzyme were 1.2, 3.4, 45.4, 4.3, and 2.0 respectively.
2. Fatty acid esters of riboflavin were not decomposed by saliva or gastric juice. They are decomposed to the vitamin by duodenal juice. In the case of R-BUT, the optimum pH and temperature were 8.5 and 40°. Rates of hydrolysis of R-PAL, R-CAP, R-BUT, R-PROP and R-ACET were 1.4, 3.5, 42.0, 18.4 and 9.4 respectively.

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Comparing the chemical properties and surface activity of thiamine dialkylsulfate with that of sodium alkylsulfate and the absorbability of thiamine dicetylsulfate with that of thiamine hydrochloride after oral administration to rabbits, the following results were obtained.
1. When the cation of sodium alkylsulfate is substituted by thiamine, an elevation of about 15° in the Krafft point resulted. Likewise, a remarkable increase in the efficiency of micelle formation and solubilizing power, and also an increase in lipophilic property are observed.
2. As the result of measurement of hydrophilic-lipophilic balance values in emulsification test, a marked increase in the lipophilic property and excellent emulsifying power are recognized.
3. The absorbability of thiamine by rabbits was indicated by the mean of the total sum of the maximal absorption as, for instance, they were 8.22 and 14.55μg per 100ml in thiamine hydrochloride and thiamine dicetylsulfate respectively.

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1. It was found that an unknown flavin compound was synthesized from riboflavinylglucoside in the culture of Rhizopus oryzae.
2. No liberation of riboflavin was observed during the culture.
3. Using several solvent systems this new compound was chromatographically distinguishable from any known flavin compounds.
4. Upon hydrolysis with H₂SO₄, flavin monophosphate-like substance was produced releasing glucose.
5. The enzymatic cleavage of this new compound by the phosphomonoesterase in Takadiastase produced riboflavinylglucoside and phosphate.
6. Each one mole of glucose and phosphate per mole of this new compound were determined chemically.
7. In the absorption spectrum there was no remarkable difference between the new compound and flavin mononucleotide.
8. This new flavin compound was suggested to be a riboflavinylglucoside mononucleotide, whose phosphate was attached to one of other ribityl carbons than 5′.
9. The biosynthesis of flavin-mononucleotide-like substance from riboflavin by the same mold was also reported.

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Purification of vitamin K₃ reductase in sweet potato was tried and a highly purified enzyme preparation, having the specific activity of approximately 5, 000 times higher than the starting crude extract, was obtained by relatively simple procedures.

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New two crystalline isomers of vitamin A palmitate are reported. These isomers are: 6-cis- and 2, 6-di-cis-vitamin A palmitates. Only neoneo-vitamin A palmitate was non-crystallizable. The corresponding vitamin A acetates were all oily products except all-trans. These esters were prepared from each crystalline vitamin A isomer.

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Orotic acid shows a whitish blue primary fluorescence which is remarkably intensified on addition of H₂O₂. Utilizing this property a histochemical method was devised. The histological technique and fundamental critical tests were described. Using this method the distribution of orotic acid in the rats loaded with orotic acid was observed. The following results were obtained.
1. Histochemical detection of orotic acid can be made by both frozen section and paraffin section method, but the latter is better.
2. Orotic acid is resorbed from the small intestine and excreted from the liver cells into the bile and from the kidneys into the urine.
3. The acid is mostly detected in the liver, brain, spinal cord, spleen, bone marrow and testes.
4. In the cells, the acid is at first taken into the cytoplasm, then into the chromatin nets and nucleoli of the nuclei.
5. In nervous cells the acid is mostly taken into Nissl's substances.

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