This review is the current summary of vitamin B₆ (B₆) biosynthesis in Escherichic coli and other microorganisms. The de novo biosynthesis of B₆ has been studied extensively for last three decades. However, the de novo biosynthesis of B₆ still remains unclear in spite of its simple structure. For the first two decades, B₆ biosynthesis had been mainly studied with E. coil using genetic, nutriticnal, and isotopic labeling experiments. According to these studies, some compounds including glycolaldehyde were identified as the precursor. During the last decade, gene manipulate techniques were rapidly developed, and complete genome sequences of some microorganisms became available. Using these new tools, valuable information has been provided. The complete DNA sequence of pdx genes and other genes, which are possibly involved in B6 biosynthesis, were shown. The roles of some genes and precursors were proposed. Besides K coil, B6 biosynthesis in other microorganisms has been also studied. In some microorganisms, snz/sno was reported to be involved in B6 bio-synthesis. Intriguingly, these genes show no similarity to any of the E. coil pdx genes, and are not found in E. coil. Microorganisms having snz/sno gene homologues lack homologues to pdxA/pdxJ genes, whereas those with homologues to pdxA/pdxJ lack snz/sno gene homologues. Therefore, it is most likely that there are at least two kinds of B6 biosynthetic pathways in microorganisms. These studies provided important clues of B₆ biosynthesis, but the entire picture of the B₆ biosynthetic pathway remains unclear.

View full abstract

The oxidant properties of iron-overload and simultaneous ethanol consumption have received much interest, due to evidence reporting from hereditary hemochromatosis (HC). The full form of this disease is often associated with chronic alcoholism. An additive effect of toxicity of iron and ethanol was assumed. In this study, we examined nutritively iron-loaded wistar rats (n=59) (TMH-Ferrocene) additionally fed with ethanol up to 8% in drinking water for 36 wk. Methods: By reverse-phase HPLC we measured the concentration of ascorbic acid, tocopherole and retinol in serum and liver homogenates as well as transaminases in the serum. Lipid peroxidation was assessed utilizing the ethane-exhalation method. Iron concentration in the liver was measured with the Bathophenanthrolinmethod. Liver histology was performed to investigate the iron deposits and the organ damage (H. E., Azan and Berlin-blue-stainings). Results: 1. Vitamin C: A linear decrease of the concentration of vitamin C in serum and liver was found independent of alcohol and iron uptake. 2. Vitamin E: Animals fed iron and alcohol showed elevated vitamin E concentrations in the serum but not in the liver. 3. Vitamin A: Elevated levels in serum but strongly decreasing levels in liver could be measured. 4. Histology: All iron-fed animals showed massive deposits of iron in the liver. Iron diet caused liver cirrhosis, while an additional administration of ethanol could prevent this. 5. Lipid peroxidation increased in animals fed ethanol and iron, but was significantly lower in animals only receiving an iron diet. Conclusion: Evidence indicates that the additional exposition to ethanol in iron-loaded animals could modulate the organ damage and oxidative stress. The biochemical findings are positively correlated to the histology.

View full abstract

Iron-deficiency or anemia in pregnancy is a major public health problem in China. This cross-sectional study was carried out to observe the association between iron status and multiple vitamin levels of Chinese pregnant women in the third trimester. We measured iron, ascorbic acid, retinol, folate and vitamin B₁₂ in serum, and riboflavin in urine specimens of 1, 163 pregnant women in four sites throughout rural and city areas in China. Based on hemoglobin concentrations (Hb), the subjects were divided into an anemia group with Hb<110g/L or Hb≤100g/L as severe anemia group, and nonanemia group with Hb≥110g/L. Results showed that 41.58% of the population with serum iron < 700 μg/L and 51.04% of the population with ferritin < 12 μg/L in the anemia group, percentages that were much higher than those in the nonanemia group. Relationships between five vitamins and hemoglobin concentrations of all subjects were observed. There was a lower level of serum ascorbic acid (291.05μg/dL) in the Hb≤-100g/L group than in the Hb≥120g/L group (487.79 μg/dL) (p<0.001). Serum levels of vitamin B12 and folate were 445.67 μg/mL and 5.94 ng/mL in the Hb≤100g/L group, whose levels were much lower than the levels of 502, 01pg/mL (p<0.012) and 8.07ng/mL (p<0, 010) respectively in the Hb≥120 g/L group. Further, cross-sectional analysis showed positive correlations between abnormal hematological results and prevalences of vitamin deficiencies. The subjects with iron-deficiency anemia had much higher rates of vitamin C, folate and vitamin B₁₂ deficien-cies than those in the nonanemic subjects, and especially in the deficient rates of ascorbic acid and folate in the anemia (Hb<110g/L) group, which reached 64.04% and 22.70% respectively. Moreover, we observed that the decreasing trends of hemoglobin concentra-tions were accompanied by the decreases of serum levels of vitamin A, ascorbic acid, folate and vitamin B₁₂. In conclusion, multiple vitamin deficiencies, especially ascorbic acid, ret-inol and folic acid, may be associated with anemia or iron deficiency in pregnant women in the last trimester. The study suggested that anemic pregnant women in China should be supplemented with iron and multiple vitamins simultaneously.

View full abstract

Resistant starch (RS) includes the sum of starch and degradation products of starch that resist small intestinal digestion and enter the colon. This study was planned to examine the effect of resistant starch on hypolipidemic actions, blood glucose, insulin levels and humoral immune responses in healthy overweight subjects. Healthy overweight sub-jects (over 120% of their ideal body weights) were fed either 24 g/d of resistant corn starch (RS) or regular corn starch (CS) for 21 d with their regular meals. Although this double-blind feeding regiment resulted in no significant changes in their weights or other physical parameters for the relatively acute period of intakes, there were significant lowering effects of serum total cholesterol (p<0.05) and serum LDL-cholesterol (p<0.05) in subjects supple-mented RS. Compared with the control starch group, the RS supplementation also reduced the mean fasting serum glucose concentrations (p<0.05). Resistant starch supplement resulted in the increase in serum immunoglobulin G (IgG) concentrations. Serum insulin and complement 3 (C₃) were unaffected. Tested resistant starch supplementation was reported to be palatable with minimal bowel discomfort. These results suggest that RS sup-plementation improves the blood lipid profile and controls the blood glucose levels in healthy overweight subjects without bowel discomfort, Therefore, RS has a potential to be used as one of the promising food ingredients for reducing risk factors involved in the development of atherosclerosis and type 2 diabetes in overweight individuals. However, in order to prove RS as a novel therapeutic agent of cardiovascular diseases and diabetes, controlled trials with larger sample sizes and longer duration are warranted.

View full abstract

The aim of this study was to evaluate the effects of Sedum sarmentosum Bunge (SS) on the lipid on serum and the collagen content of the connective tissues in ovariecto-mized estrogen-deficient rats. Three groups were surgically ovariectomized. The fourth group was sham operated. From day 2 until day 37 after the ovariectomy, Sprague-Dawley female rats were randomly assigned to the following groups: sham-operated rats (sham), ovariectomized control rats (OVX-control), ovariectomized rats supplemented with an ethyl ether fraction of SS at 10mg/kg bw/d (OVX-EE), ovariectomized rats supplemented an ethyl acetate fraction of SS at 10mg/kg bw/d (OVX-EA). The SS fractions were orally adminis-trated at 1 mL per day. The estrogenic effects of the ethyl ether and ethyl acetate fractions of SS, were investigated using one in vitro assay and two in vivo assays. The treatment of the partition of the ethyl ether and ethyl acetate layers of SS increased the transcriptional activ-ity 0.7-fold and 0.5-fold compared to those that were given 17β-estradiol treatment, respec-tively. The OVX rats were significantly heavier than the sham-operated rats at all times, but supplementation with the SS extracts tended to result in less weight gain than OVX-control. The serum triglyceride levels were significantly decreased after supplementation with the SS portion BE and EA layers. Supplementation with the SS extracts prevented a decrease in the collagen level in bone and cartilage tissues. This result indicates that the SS affects the col-lagen synthesis in ovariectomized rats. These results are consistent with the conclusions based on the estrogenic activities of SS. Therefore, it may be used to possibly improve the quality of life in menopausal women.

View full abstract

The beneficial effects of high-monounsaturated fat (high-MUFA) diets on dia-betic patients have been reported, whereas studies concerning the effects on animals have been few. Although experiments on animals should be useful in elucidating underlying mechanisms, it is not clear even whether there are benefits of a high-MUFA diet in animals. This study examined the short-term effects of a high-MUFA diet on normal and genetically diabetic mice. The high-MUFA diet supplied 38% of the total calories as fat (26% from MUFA), while a regular diet was 13% fat (3% from MUFA). Normal C57BL/6J and diabetic C5 7BL/KsJ-db/db mice were fed either the regular or the high-MUFA diet for 1 wk. Serum glucose and lipid levels were then measured. In normal mice, hepatic triglyceride production was also compared between the two dietary groups using the Triton WR 13 3 9 method, An oral glucose tolerance test was conducted on the diabetic mice. After 1 wk of feeding to nor-mal mice, the high-MUFA diet was seen to lower serum triglyceride levels and reduce hepatic triglyceride production in comparison with the regular diet; it is suggested that the lowering of triglyceride consists of mechanisms including reduced hepatic triglyceride production. When diabetic mice were fed the high-MUFA diet with a controlled caloric intake, the serum glucose levels lowered without an accompanying deterioration in lipid metabolism and the impaired glucose tolerance was ameliorated. This study demonstrates that a high-MUFA diet can lower serum triglyceride levels in normal mice and improve disorders of glucose metab-olism in diabetic mice.

View full abstract

A therapeutic agent of vitamin K₂ is approved for the treatment of osteoporosis in Japan. However, little is known about the efficacy of dietary intake of vitamin K₂ for bone health. We compared the effects of various levels of fermented soybeans (Natto) intake, which contains plenty of vitamin K₂, on bone stiffness and bone turnover markers in healthy premenopausal women. Seventy-three healthy premenopausal women were ran-domly divided into four groups matched for age and parity categories. Natto was supplied as follows; Group 1 (no intake), Group 2 (once per month), Group 3 (once per week) and Group 4 (three times per week). Subjects took Natto at a lunch for 1 y, and the stiffness index by quantitative ultrasound and bone turnover markers were assessed at baseline, 6 mo and 1 y There was no statistical difference in the stiffness index during the 1 y observation. How-ever, bone specific alkaline phosphatase (BAP) in Group 4 was higher than that in Group 3 at 1 y and undercarboxylated osteocalcin (Glu) in Group 4 was significantly lower than those in Groups 1, 2 and 3 at 6 mo. Logistic regression analysis showed that the risk of reduction of bone formation markers declined to 0.07 in Group 4 based on that in Group 1. In premenopausal women who had to keep the stiffness index as high as possible before menopause, Natto intake may have contributed to the promotion of bone formation.

View full abstract

In this study, we compared three acid-catalyzed methods and three base-cata-lyzed methods for the methylester preparation of conjugated dienoic fatty acids and conju-gated trienoic fatty acids in food and biological samples. Among the six methods examined, the sodium methoxide/methanol (NaOCH₃/MeOH) method and the tetramethylguanidine/ methanol (TMG/MeOH) method of niethylester preparation from tung oil were most efficient in preventing the artificial isomerization of α-eleostearic acid (α-ESA; 9c, 11t, 13t-18:3) to β-eleostearic acid (β-ESA; 9t, 11t, 13t-18:3) and for avoiding the artificial genera-tion of unknown byproducts. Hydrochloric acid/methanol (HCl/MeOH), sulfuric acid/meth-anol (H2SO₄/MeOH) and AOCS (boron trifluoride/methanol (BF₃/MeOH)) methods of methylester preparation from tung oil resulted in the breakdown of α-ESA due to their long reaction periods and high reaction temperatures. In addition, these three methods did not prevent the generation of β-ESA. For the methylester preparation of tung oil free fatty acids, the BF₃/MeOH method (30min at room temperature) did not lead to artificial β-ESA forma-tion or byproducts, while the trimethylsilyldiazomethane (TMSN₂CH₃) method did form artifacts. For the methylation of conjugated linoleic acid (CLA, free fatty acid), the BF₃/MeOH and TMSN₂CH₃ methods completely suppressed artificial isomerization of c, t-CLA and t, c-CLA to t, t-CLA. The results indicated that the BF₃/MeOH method for free fatty acids is the best method for the methylester preparation of both conjugated dienoic and trienoic fatty acids with respect to preventing artificial isomerization and the formation of byprod-ucts. The BF₃/MeOH method was applicable to both food and biological samples.

View full abstract

In the present study, we have investigated the effects of phycocyanin, a biliprotein of Spirulina platensis, on mucosal and systemic immune responses and allergic inflammation in C₃H/HeN and BALB/cA mice. To induce the antigen-specific antibodies in the peripheral lymphoid tissues such as Peyer's patches and mesenteric lymph nodes, biodegradable ovalbumin-entrapped poly (DL-lactide-co-glycolide) particles were used as an antigen. Two weeks after the onset of phycocyanin ingestion, mice were immunized with an aqueous ovalbumin (OVA) solution. Starting at one week after the primary immunization, the mice were subjected to oral immunization with the biodegradable OVA microparticles twice a week. IgA, IgE and IgG 1 antibodies were determined by ELISA. The OVA icroparticles of 4-μm diameter successfully induced antigen-specific antibodies. In the mice that received phycocyanin treatment for 6 wk, a marked increase in the antigen-specific, as well as the total, IgA antibody level was observed in the Peyer's patches, mesenteric lymph nodes and intestinal mucosa as well as in the spleen cells. Both antigen-specific IgG 1 and IgE antibody levels in the serum were suppressed by ingestion of phycocyanin for 8 wk. However, inflammation of the small intestine, monitored as vascular permeability by the Evans blueleaking method was reduced by phycocyanin at 6 wk, which preceded the suppression of antigen-specific IgG 1 and IgE antibody production by 2 wk. These results suggest that phycocyanin enhances biological defense activity against infectious diseases through sustaining functions of the mucosal immune system and reduces allergic inflammation by the suppression of antigen-specific IgE antibody.

View full abstract

This paper describes the antitumoral activity of branched-chain fatty acid (BCFA) in human breast cancer cells with an emphasis on its effect on fatty acid biosynthesis. First, the relationship between chain-length and antitumoral activity was studied. The highest activity was observed with iso-16.0, and the activity decreased with increase or decrease of the chain-lengths from C 16:0. Anteiso-BCFA, as well as iso-series, was cytotoxic to the breast cancer cells. Cytotoxicity of BCFA was comparable to that of conjugated linoleic acid known as antitumoral fatty acid. Incubation of breast cancer cells with BCFA (13-methyltetradecanoic acid) significantly reduced the [¹⁴C] acetate incorporation into free fatty acid and fatty acid esters, showing the inhibition of fatty acid biosynthesis by BCFA. Examination of substrate level effect found that BCFA slightly inhibited fatty acid synthetase and acetyl-CoA carboxylase, and significantly the glucose-6-phosphate dehydrogenase which was the main NADPH generating system in breast cancer cells. The present study thus suggests that BCFA synthetically lowers the fatty acid biosynthesis by reducing the precursors, in addition to its direct inhibitory effect on fatty acid synthetase.

View full abstract

Despite its toxicity, a great deal of attention has been paid to the anorexic effect of capsaicin in the treatment of obesity-related neurotransmitters/neuromodulators. To determine if capsaicin has any effects on the orexigenic or anorexigenic peptides, the neuropeptide Y (NPY) and cholecystokinin (CCK)-imunoreactivities were demonstrated in the rat hypothalamus by immunohistochemistry after capsaicin administration. There was a significantly lower concentration of NPY immunopositive cells in the arcuate and paraventricular nuclei of the capsaicin treated rats. In contrast, the CCK expressions level was higher in the paraventricular nucleus of the capsaicin treated rats than in the control rats. These results suggest that capsaicin influence neuropeptides such as orexigenic NPY and anorexigenic CCK related to control food intake.

View full abstract

We examined whether short-term ascorbic acid deficiency impairs antioxidant status in the lens of guinea pigs. Male guinea pigs aged 4 wk were given a scorbutic diet (20g/animal per day) with and without ascorbic acid (400mg/animal per day) in drinking water for 3 wk. The ascorbic acid-deficient group showed no lens opacity. The ascorbic aciddeficient group had 14% of serum ascorbic acid concentration, 6% of aqueous humor ascorbic acid concentration, and 18% of lens ascorbic acid content in the ascorbic acid-adequate group. There were no differences in the contents of lens reduced glutathione and thiobarbituric acid reactive substances, an index of lipid peroxidation, between the ascorbic acid-deficient and adequate groups, while the deficient group had higher lens vitamin E content than the adequate group. The ascorbic acid-deficient group had higher serum vitamin E concentration than the ascorbic acid adequate group, while there were no differences in the concentrations of serum reduced glutathione and tiobarbituric acid reactive substances between the deficient and adequate groups. These results indicate that short-term ascorbic acid deficiency does not impair antioxidant status in the lens of guinea pigs despite induction of severe ascorbic acid depletion in the tissue, which may result in no cataract formation.

View full abstract