After orally administering varying amounts of β-carotene dissolved in oil or of vitamin A palmitate in oil to a healthy male adult, the changes in serum vitamin A and carotene levels were traced. Comparing the maximum values for serum vitamin A increase after administering the same I.U. of vitamin A palmitate or β-carotene, the value following β-carotene administration was about 25% of that for vitamin A palmitate. After ingesting varying amounts of cooked squash, carrot and spinach, respectively, the increase in serum vitamin A and carotene levels was compared with that after ingesting pure β-carotene solution. The maximum values for increase in serum vitamin A levels after ingesting vegetables were about 31-55% of those after ingesting the same I.U. of β-carotene solution and those for increase in serum carotene levels were about 50% of those after ingesting β-carotene. The absorbability of carotenes in vegetables, therefore, is considered to be about 30-50% of that of pure β-carotene solution.

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The reaction product of riboflavin with P_2S_5 was hydrolysed in 1 N NaOH solution, and urea was isolated as dixanthydrylurea. As the control experiment 2-thiolumiflavin was hydrolysed, and thiourea was detected. It was thereby confirmed that the chemical structure of S-derivative was 4-thioriboflavin. Vitamin activity of this compound was not more than one tenth of that of riboflavin.

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In albino rats fed on a synthetic diet, contraction and reepithelization of skin wound were hastened by the administration of orotic acid. Orotic acid injection also caused a slight promotion of wound healing in rats and adult dogs whose liver had been damaged by an intramuscular injection of carbon tetrachloride. Furthermore, the mortality of the poisoned rats was remarkably lowered by the administration of orotic acid.

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The acetate replacing activity of DL-α-lipoic acid used for the growth of Streptococcus faecalis R was markedly affected by the composition of the medium. When a semisynthetic basal medium supplemented with casamino acid (Difco) as an amino acid source was used, the ability of DL-α-lipoic acid to replace acetate was greatly enhanced in the presence of sodium citrate or pyruvate. In the absence of the substances, however, DL-α-lipoic acid has no activity to support the growth of St. faecalis R. Such activity enhancing effect of sodium citrate and pyruvate was not observed when a synthetic medium was used. In the synthetic medium, DL-α-lipoic acid acted for acetate without help of other substances. From the results mentioned above, two assay methods of DL-α-lipoic acid using St. faecalis R were proposed. The first is to calculate from the acetate replacing activity in the semisynthetic medium supplemented with sodium citrate. The second consists of utilizing the antagonistic activity of DL-α-lipoic acid to the growth inhibiting activity of propionic acid. In the latter, the assay medium was that described by Stokstad but modified a little. In this simplified medium, the irreguler response of St. faecalis R which was observed occasionally was fairly diminished.

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In rats orally administered with 200 mg/kg/day of Aureomycin, the thiamine content and α-ketoglutarate oxidizing activity in the liver decreased for the first two weeks, increased slightly in the third week, and again decreased in the fourth to sixth week, always both in parallel. In the brain both did not change till the forth week, they, however, decreased in the fifth to sixth week. Ratio of free to esterified forms of thiamine did not decrease in brain and liver. When cocarboxylase was added to homogenized brain or liver tissues with low thiamine content and α-ketoglutarate oxidation activity, an imperfect improvement was observed. While in the control animals no influence was caused. The magnecium ion content which is indispensable for α-ketoflutarate oxidation was 9×10^<-3> M in brain and 6×10^<-3> M in liver. In addition of 4μg/ml of Aureomycin or Achromycin, in vitro, α-ketoglutarate oxidation was checked by chelation to Mg". This action was stronger in brain than in liver.

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When 20mg/kg/day of Aureomycin was given to young rats, a promotion of growth was observed, while 200mg/kg/day of Aureomycin retarded the growth. In this case no parallelism was noticed between the nitrogen content of brain and that of liver tissue. The thiamine content and α-ketoglutarate oxidizing activity in the liver of rats, orally administered with 20mg/kg/day of Aureomycin, increased slightly in parallel at the biginning, but there was no considerable change on the whole, and the ratio of free to esterified forms of thiamine was not considerably changed. When Aureomycin was added to brain tissue homogenate of the control animals, α-ketoglutarate oxidizing activity was almost unchanged.

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When 20mg/kg/day of Achromycin was given to young rats the growth was promoted, while it was checked when 200mg/kg/day was administered. The effects were, however, slighter than those by Aureomycin. No significant relation was noticed between the growth promotion and the nitrogen contents of liver and brain tissues. Thiamine content and α-ketoglutarate oxidizing activity in the liver of rats, administered with 200mg/kg/day of Achromycin, decreased in parallel in the second week, increased slightly in the third week and again decreased in the fourth week. In the brain they underwent no change till the sixth week. No change of the ratio of free to esterifled thiamine was observed.

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Thiamine content and α-ketoglutarate oxidizing activity in liver of rats, orally administered with 20mg/kg/day of Achromycin increased in parallel temporarily at the beginning, decreased during the second and the third weeks, and again increased in the fourth week. No change in the ratio of free to esterified thiamine was noticed. By addition of cocarboxylase to liver homogenate, with lowered α-ketoglutarate oxidizing activity, the activity was regained but not to a sufficient degree. In the control rats, the α-ketoglutarate oxidizing activity of liver or brain homogenate showed a slight increase by the addition of Achromycin.

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An assay method for determining of the forms of the thiamine in bakers' yeast was investigated. Inactivation of the phosphatases in yeast by heating before extraction was found to be most suitable. Using this method, the thiamine in yeast was proved to be all in an esterified form. Further, the thiamine formed from the pyrimidine and thiazole moieties by living yeast cells was also estimated. The cells washed with water converted the esterified thiamine to the free form during incubation. This conversion to the free form was less marked in unwashed cells.

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The vitamin requirement of distillers' yeast was examined with six strains, used in the distillers' factory. One strain required pantothenic acid and five strains pantothenic acid and biotin as essential growth factors. Inositol, pyridoxine and thiamine had the growth stimulating action for most of the strains, while in one pantothenic acid requiring strain biotin had also stimulatory action. The necessary concentration of the vitamins for maximal growth was as follows : pantothenic acid 200-400 mμg/ml, inositol 2μg/ml, and biotin 5 mμg/ml.

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Distillers' yeast requires both biotin and pantothenic acid as essential growth factors and thiamine as a growth stimulant as shown in the preceding paper. However thiamine exerts a significant inhibitory action on the yeast growth and consequently alcohol production, when it is added to the medium which contains one of the two essential vitamins in enough amount and the other only in small quantity. The inhibitory effect is observed more clearly in the case of biotin deficiency. In the presence of enough amount of biotin, the optimal ratio of pantothenic acid to thiamine for alcoholic fermentation is 2 : 1 to 1 : 1. From these results it is considered that well balancing of the vitamins is important for an alcoholic fermentation in yeast.

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