The information on B_6 conjugates in plants are summarized as follows. 1. A main component of B_6 in most plant foods is glycosylated B_6. In addition, a new type of B_6 conjugate releasing free B_6 when treated with alkali and then β-glucosidase was present in brans and legumes. Three new pyridoxine (PN) glycosides were isolated from rice bran and identified. 2. The hydroxyl radical generated during autoxidation of ascorbic acid was proposed to be responsible for a loss of B_6 activity during storage, processing and cooking of plant foods. 3. The main metabolite of PN in plant seedlings was 5'-O-(β-D-glucopyranosyl) pyridoxine (PNG), and minor ones in seedlings of podded pea, Pisum sativum L. cv. Kinusaya, were 5'-O-[6-O-(3-hydroxy-3-methyl-4-carboxybutanoyl)-β-D-glucopyranosyl] pyridoxine and 5'-O-(6-O-malonyl-β-D-glucopyranosyl) pyridoxine. A UDP-glucosyltransferase catalyzing formation of PNG seemed to be widely distributed in plants. Properties of the particulate enzyme isolated from seedlings of podded pea were examined.

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1) Determination of total thiamin: Blood was deproteinized and the supernatant was adjusted to pH 4.5 with CH_3COONa. Then diastase was added to the supernatant and incubated at 37℃ for 8〜10 hours. For HPLC, the mobile phase (0.2M NaH_2PO_4) was eluted at a flow-rate of 0.3ml/min. A sample was loaded on the sample loop and then injected into the column. Potassuim ferricyanide (0.05%) in sodium hydroxide (15%) solution applied at 0.3ml/min by a proportioning pump was mixed with the column effluent to convert thiamin into a fluorophore. The intensity of the fluorophore was measured with a spectrofluorophotometer and recorded graphically. Using this method, thiamin concentrations in the blood of humans and animals were determined. Average thiamin concentrations in the blood were 1.54×10^<-7>mol/l, 8.09×10^<-7>mol/l and 8.57×10^<-7>mol/l in humans, rats and rabbits, respectively. This method is simple and highly reproducible, and its sensitivity is sufficient for determination of the thiamin content of as low as 20μl blood samples. 2) Determination of thiamin and its phosphate esters: Blood was deproteinized and centrifuged. Aliquots of the samples are applied to a μBondapak C_<18> column attached to a high-performance liquid chromatograph. The mobile phase (0.2M NaH_2PO_4 in 0.3% acetonitril) was eluted at a flow-rate of 1.0ml/min. Addition of potassium ferricyanide/sodium hydroxide solution to the column effluent with a proportioning pump converted thiamin phosphate into fluorophores, the intensities of which were measured with a spectro-fluorophotometer. In human blood, thiamin pyrophosphate was present in the highest concentration, followed by thiamin triphosphate. Thiamin monophosphate and thiamin were present in small amounts. In rat blood, thiamin pyrophosphate was found in the largest amount, followed by thamin monophosphate. Thiamin triphosphate and thiamin were present in small amounts. Reliability and sensitivity of these methods were satisfactory.

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Neonatal vitamin K deficiency causes early and classic HDN (hemorrhagic diseases of the newborn). There have been some suggestions as to how to prevent from having vitamin K deficiency in babies. However, early HDN could not be prevented by vitamin K administration after birth even as soon as possible. To prevent early HDN, we have attempted to administer vitamin K_2 syrup to 15 mothers before delivery, and measured vitamin K_2 in maternal and umbilical cord plasma at birth and breast milk 5 days after delivery. The mean K_2 values in maternal and umbilical cord plasma and in breast milk were significantly high as compared with those of 15 cases of control. Therefore, oral administration of vitamin K_2 syrup to mother before delivery is more preferable than intramuscular injection to neonate, which involves a certain degree of danger. This preventive method is safe, and causes early and continuous transportation of vitamin K_2 from mother to neonate.

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Nutritional status of water-soluble vitamins in the elderly was studied from a few points of their intestinal absorption, metabolism, metabolic aspects and effects of oral administration of the vitamins. Furthermore, the relationship between several immunologic indices and the blood concentrations of vitamin B_6 (B_6) was also investigated. 1) Nine of 16 cases showed low blood concentrations of B_6, while a few cases showed low blood concentrations of vitamins B_1 and C. 2) In. B_6 compounds, pyridoxine hydrochloride was well absorbed from the intestine, and mainly converted into its active form, pyridoxal phosphate. 3) Blood concentrations of vitamins B_2 (B_2) and B_<12> (B_<12>) were in the range of normal values, and oral administration of B_2 and B_<12> did not elevate their concentrations in sera. 4) Weak relationship between serum concentration of B_6 and T_8 lymphocyte ratio was recognized.

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