Occurrence, metabolism and physiological functions of L-ascorbic acid have not been reported in Euglena gracilis, a flagelate protozoon. In view point of the unique phylogenetic position of Euglena, plant-like on one hand and animal -like on the other, elucidations of the pathway and subcellular distribution of L-ascorbic acid biosynthesis and of the physiological functions of the acid are highly interesting and might make contributions to understanding the functions of L-ascorbic acid in other organisms. The present review describes the biosynthesis of L-ascorbic acid, effect of light on the cellular acid content and disposal of peroxides by new L-ascorbic acid peroxidase in E. gracilis, with special emphasis on its role in protection of the cells from oxygen toxicity.
To study the effect, of vitamin B_<12>-deprivation on methylmalonic acid (MMA) excretion in urine, weanling rats were fed on vitamin B_<12>-deprived diet for 130 days. Growth rate and hematological change of peripheral blood were also observed. Furthermore, urinary MMA was determined by isotachophoresis. Growth of the group fed on the vitamin B_<12>-deprived diet was retarded, and decreased in food intake and food efficiency. Red blood corpuscle, hemoglobin and hematocrit value of peripheral blood were decreased compared with vitamin B_<12>-supplemented group. The determination of MMA by isotachophoresis, that was reported previously, was compared with colorimetric method, and this new method was expected to be used as simple assay procudure of urinary MMA. As the result of the MMA determination, it was observed that urinary MMA excretion was increased with the progress of experimental period.
The effect of intravenous administration of vitamin C (15 mg per day, corresponding to 40〜50 g for human adults) upon the immune response was investigated in mice. In vivo antibody production to sheep erythrocytes (SRBC) was not influenced. Similarly, in vitro immunoglobulin production and DNA synthetic response of spleen cells to pokeweed mitogen were hardly affected by vitamin C administration. On the other hand, delayed-type hypersensitivity to SRBC was strongly suppressed by vitamin C intake. Cell transfer experiments revealed that only the expression phase but not the induction phase of delayed hypersensitivity was suppressed.
The changes of forms of cobalamins in human serum and urine following oral and intramuscular administration of CN-B12, OH-B12, DBCC and CH3-B12 were measured by chromatographic microbioassay. The total serum cobalamin levels after a single oral dose of 3,000 /μg of cobalamins reached the maximum of 150〜160 per cent in 3 hours as compared with the respective pre-treatment levels, being due to an increase of the similar forms as cobalamins given orally. As to the excretion of cobalamins in the urine after oral administration of cobalamins, it was found that 1.3〜1.9 μg of the similar forms as cobalamins given orally was excreted in the first 8 hours. When the changes of serum cobalamin levels in human after oral dose of 1,500 μg cobalamins daily were compared among respective cobalamins, no significant differences were observed. After continuous intramuscular administration of cobalamins, serum CN-B_<12> level was low and urinary excretion of CN-B_<12> in-creased in the CN-B_<12>-administered group as compared with other cobalamins -administered groups.