In the protein depleted rats, plasma total protein and albumin were decreased remarkably by the operative stress, but by the administration of orotic acid the postoperative decrease of them was improved and the postoperative increase of α- and β- globulin was supressed. These disturbances were improved more evidently dy the addition of orotic acid to all amino acids than the latter only.

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This paper reports the inhibiting action of riboflavin in the light condition on the activity of tyrosinase, extracted from the potato tubers. Both riboflavin and its photolized products, i. e., lumiflavin and lumichrome, inhibit the tyrosinase activity in the light and each inhibiting effect is the following descending order : lumiflavin>riboflavin>lumichrome. The tyrosinase activity was inhibited by both Na-diethyldithiocarbamate and KCN, but not by Naethylenediaminetetraacetate, among the chelating reagents used in this experiment. The addition of Cu^<2+> reversed considerably the inhibition of tyrosinase activity by Na-diethyldithiocarbamate and KCN, but not by riboflavin.

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For the determination of vitamin A in pharmaceuticals, Mulder's method has advantages in rapidity and precision, compared with U.S.P. method. But Mulder's method tends to give higher values, which vary according to the forms of preparations. The authors proved that the cause of higher value was chiefly in the washing process by KOH, i.e. benzene was dissolved into water phase to some extent while vitamin A not, thus resulting in a relative concentration of vitamin A. This phenomenon was not recognized in the use of cyclohexane instead of benzene as extracting solvent. The cyclohexane method was applied to U.S.P. vitamin A reference standard and various forms of vitamin A preparations, and it was proved that the results were in good agreement with those of U.S.P. method.

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Several studies relating to the separation and estimation of L-ascorbic acid and erythorbic acid were reported about the method using acetonitrile system and the method using methylethyl ketone system. The authors scrutinized these two methods for the purpose of separation and estimation of the both acids in foods and confirmed that the method using methylethyl ketone system was excellent. At the same time, it was found that some part of the both acids was oxidized in process of paper chromatography. Therefore, in order to estimate exactly the both acids, it was necessary to make the curve of survival ratio in process of paper chromatography and amend detection ratio. In case of using methylethyl ketone system for the separation and estimation of the both acids added to several foods and amending detection ratio, detective error was about 10% for the both acids.

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In order to ascertain the correct dosis of thiamine for treatment of thiamine deficiency, experiments were made on rats which were repeatedly made thiamine deficient, and it was noticed that the necessary curative dosis of thiamine varied from physiological requirements. Larger doses of thiamine were necessary when the rats were in a state of chronic thiamine deficiency. The same can be considered in the treatment of men.

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In the normal persons, ^<35>S is excreted in urine amounting 91-99% of injected lipoic acid-^<35>S within 24 hours. After peritoneal injection of lipoic acid-^<35>S in mice, ^<35>S invaded rapidly into the tissues and disappeared rapidly. With seven eczematic patients, the excretion of ^<35>S was less than that with normal subjects and the excretion peak was seen with the latter but not with the former. Unkown 5 spots of ^<35>S were seen on paper chromatogram. It seems that some relationships exist between disturbance of lipoic acid metabolism and hepatic, renal and adrenal disfunction and disorder of serum protein and blood sugar.

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The quantities of total and each flavin, and the activities of D-amino acid oxidase in the liver and kidney of vitamin D deficient, vitamin D administered rats and rats fed on standard diet were studied. Total flavins in the vitamin D deficient group was almost the same as those of the control (vitamin D deficient diet+vitamin D). However, in the normal group (fed on standard diet) higher levels of flavins than these two groups were found. In separative determinations of flavins, FAD of vitamin D deficient group were lower than that of the other. Activities of D-amino acid oxidase of these three groups were compared with each other and lower activities were found in the vitamin D dificient group.

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Quantities of flavins and activities of D-amino acid oxidase in the liver and kidney of vitamin D injected rats (100,000 I.U. or 150,000 I.U.) were estimated. The quantities of total flavins and FAD in the liver and kidney of hypervitaminotic rats were considerably lower than those of normal rats. D-Amino acid oxidase activities of hypervitaminotic rats were slightly lower than those of normal rats.

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Thiaminase II, a hydrolytic enzyme, catalyzes the reaction between thiamine and water. On the other hand, it can also be presumed that the reaction between thiamine and OH ion may be an essential one. In either case of these two types, the reaction belongs to a second order reaction. Thus the general enzyme-kinetics in the second order enzymatic reaction were studied under the condition that one of two substrates was kept at a constant concentration throughout the reaction. New equations of the second order enzymatic reaction were presented. From these equations the following results are expected, when the two substrates are represented as A and B, and when the substrate B is kept at a constant concentration during the reaction : In the case of high concentration of B such as H_2O, the type of equation becomes similar to the Briggs-Haldane's type of Michaelis-Menten's equation. In the case of low concentration of B such as OH ion, the equations suggest that the inhibitory effect may be brought about by the substrate A, and that the values corresponding to Km may be changed by the concentration of B. The thiaminase II catalysis showed practically such results as expected from the consequences in the case of low concentration of B. Then the enzymatic reaction should essentially be a second order reaction between thiamine and OH ion.

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Intraperitoneal administration of benzenesulfonylthiamine disulfide (I) (5mg equivalent to thiamine-HCI) to rats resulted in such a low urinary thiamine excretion in 24 hours as 3% of the dosage, suggesting destruction of I in animals instead of the reduction to benzenesulfonylthiamine (II). On incubation of I with the homogenate of rat liver at pH 6.0 for 3 hours, the majority of I was decomposed, showing less than 10% the recovery of I, while on the incubation at pH 4.5,I was more stable and more than 75% of I were recovered as II. The reaction was shown to be non-enzymatic, because the boiled homogenate was also capable of decomposition and reduction. The reduction of I to II by cysteine or thioglycolic acid was checked at the ranges of pH between 3 and 8 : A quantitative recovery to II was observed only at pH 3-4 and such a poor recovery less than 10% at the higher pH than 6 was shown with the simultaneous formation of thiamine-anhydride which was isolated as crystals of mp. 110℃. When I was given intraperitoneally to rats, I was probably decomposed to thiamine-anhydride and its further metabolites, and only a metabolite similar but not identical to thiamine-anhydride sulfoxide was detected on its paper chromatogram. Biological activity of I to thiamine-deficient rats, was proved to be non-effective for growth-stimulation at the dosage of 20μg equivalent to thiamine-HCl on every other day, but at the 200μg level, I was shown to be effective by both oral and intraperitoneal administration.

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By adding hydroxocobalamin to the culture medium modified by the authors, biosynthesised amounts of DBCC were found to increase strikingly in the cells of Pr. shermanii. From the cells so obtained, crystalline coenzyme was prepared very easily by adopting chromatography on column of P-cellulose as the main purification procedure.

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Cyanocobalamin was found to be utilized as the precursor of DBCC by Propionibacterium shermanii as well as hydroxocobalamin, when added to the culture medium. Based upon the results, more useful method for preparing DBCC was established. It consists of cultivating Pr. shermanii in the presence of cyanocobalamin, harvesting the cells by centrifugation, extracting DBCC by homogenizing the cell paste with absolute alcohol, concentrating the extracts under reduced pressure, chromatographic separation on column of DEAE-cellulose or P-cellulose, treatment with phenol and crystallization by addition of acetone.

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