VITAMINS

New biochemical processes for production of vitamins and coenzymes were developed with microorganisms selected by screening. Menaquinone-4-producing process was established with derivation of mutant from menaquinone-producing Flavobacterium sp., optimization of cultural conditions, and extracellular accumulation by detergent-supplemented culture. Intracellular content of α-tocopherol of Euglena gracilis was increased by mutagenization and optimization of cultural conditions. A new system of ATP production involving the oxidative phosphorylation, oxidation of methanol and salvage synthesis of adenine nucleotide was constructed with cells of a methylotrophic yeast. A high intracellular content of cytochrome c was achieved with a cyanide-resistant mutant of an obligate methylotrophic bacterium.

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The effects of α-tocopheryl succinate (Toc-suc), riboflavin (RF) and ascorbic acid (AsA) on chromate-caused DNA damage, enzyme inhibition and cellular reduction of chromium (VI) were investigated using Chinese hamster V-79 cells. Pretreatment with Toc-suc or AsA resulted in a decrease of DNA single strand breaks or alkali-labile sites produced by Na_2CrO_4, while similar pretreatment with RF enhanced levels of both DNA damages. In contrast, levels of DNA-protein crosslinks caused by Na_2CrO_4 were unaffected by Toc-suc or RF, but the levels were increased by AsA. Pretreatment with Toc-suc or AsA restored glutathione reductase activity suppressed by Na_2CrO_4, however, RF pretreatment enhanced the inhibition of this enzyme by this metal. Using a colony-forming assay, pretreatment with Toc-suc dramatically decreased the cytotoxicity of Na_2CrO_4, and similar treatment with RF was found to result in only a decrease of cell lethality of this metal, while the cytotoxicity of chromate was enhanced by AsA. The uptake of chromate was not affected by Toc-suc or RF, but increased by AsA pretreatment. Electron spin resonance (ESR) studies showed that pretreatment with Toc-suc or AsA reduced the level of chromium (V) complex in cells, whereas RF pretreatment enhanced the level of this intermediate. With respect to chromium (III), AsA pretreatment was found to increase, but Toc-suc or RF did not. These results indicate that vitamins are capable of altering the biological effects of carcinogenic chromium (VI) compounds, possibly through their abilities to modify levels of paramagnetic chromium in cells. the importance of the role of vitamins in chromium (VI)-induced carcinogenicity and toxicity is discussed.

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One-month old male rats who were treated with streptozotocin injection, were fed the diets containing 5% olive oil 5% fish oil for 2 weeks. Influence of the dietary fat on concentrations of triglyceride (TG), total cholesterol (Chol) and α-tocopherol (Toc) in serum and several organs of the rats was investigated. In the normal rats, serum TG, total Chol, Toc and liver Toc of the fish oil group were significantly lower than those of the olive oil group. In the diabetic rats however, this effect of the fish oil diet on the concentration of these lipids in serum and liver of rats was not significant, although the serum and liver lipids of the diabetic rats were elevated. On the other hand, ratio of 20:4/18:2 in liver phospholipids of the fish oil groups was lower on both normal and diabetic rats, as compared with those of the olivie oil groups. The ratio of 22:6/22:5 in liver phospholipids of the diabetic rats fed the fish oil diet was higher than that of the normal rats. These results suggest that the correction of the hyperlipidosis in serum and liver by fish oil diet may be difficult in diabetics, and that a desaturase activity may decrease with the fish oil diet in both the normal and diabetics rats.

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The vitamin C activity of L-threo-hexo-2-enaro-1,4-lactone ehtyl ester (ES-AsA) has been studied. Oral administration of 0.015 mmol/animal/day of ascorbic acid completely prevented development of scurvy in young male Hartley guinea pig fed on vitamin C free diet. 0.03 mmolar and 0.05 mmolar of vitamin C analogue (ES-AsA) did not prevent and cure scurvy. Vitamin C levels in tissues, serum alkaline phosphatase activities and hydroxyproline contents in tibia of ES-AsA administered groups were similar to those in vitamin C-free diet group animals. The results of this investigation indicate that the close relationship may exist between chemical structure of C-6 position of ascorbic acid analogues and the development of vitamin C activity, as ES-AsA does not prevent and cure scurvy in the guinea pigs.

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