Identification of pheophorbide a as an inhibitor of receptor for advanced glycation end products in Mallotus japonicus.

Accumulation of advanced glycation end products (AGEs) plays an important role in diabetes, immunoinflammation, and cardiovascular and neurodegenerative diseases. Since AGEs mediate their pathological effects through interaction with receptor for AGEs (RAGE), RAGE antagonists would provide a useful therapeutic option for various health disorders. Therefore, in this study, we aimed to identify phytochemicals that would inhibit binding of AGEs to RAGE, which may help develop new drug leads and/or nutraceuticals for AGE-RAGE-related diseases. On screening ethanol extracts obtained from 700 plant materials collected in Myanmar, we found that the ethanol extract from the leaves of Mallotus philippensis inhibited the binding of AGEs to RAGE. We also found that the leaves of M. japonicus, which belongs to the same genera and distributes abundantly in Japan, exhibited the inhibitory activity similar to M. philippensis. Activity-guided fractionation and LC/MS analysis of the ethanol extract of M. japonicus helped identify pheophorbide a (PPBa) as a major component in the active fraction, along with some other pheophorbide derivatives. PPBa exhibited potent inhibitory activity against AGE-RAGE binding, with an IC50 value (0.102 µM) comparable to that of dalteparin (0.084 µM). PPBa may be a valuable natural product for use as a therapeutic agent and/or a nutraceutical against various health complications arising from activation of the AGE-RAGE axis.

Evaluation of the prevalence of iodine intakes above the tolerable upper intake level from four 3-day dietary records in a Japanese population.

The Japanese population routinely consumes iodine-rich seaweed, thereby probably making Japan the nation with the highest iodine intake worldwide. The present study aimed to estimate the duration of dietary records (DRs) needed to calculate the usual iodine intake and to ascertain the frequency of iodine intakes above the tolerable upper intake level (UL) in the Dietary Reference Intakes for Japanese. Four 3-d DRs for the 4 seasons within a year were collected for 55 men and 58 women. On the basis of analysis of variance, the total variance in iodine intake was classified into inter-individual and intra-individual components. The frequency of appearance for high iodine intakes was estimated. The most commonly consumed types of iodine-containing food items were seaweed, milk and milk products, fish and shellfish, and tofu. The percentage contribution of intra-individual variance was markedly greater than that of inter-individual variance, and the excessive iodine intake was intermittent rather than continuous. The duration for which dietary records were required to assess the usual intake of iodine within 10% of their true mean was 6,276 d for men and 4,953 d for women. The period that transpired until a value was exceeded once was 6.3 d/occurrence for values above UL (2,200 µg), 8.5 d/occurrence for values above 3,000 µg, 9.8 d/occurrence for values above 4,000 µg, 11.2 d/occurrence for values above 5,000 µg, and 16.7 d/occurrence for values above 10,000 µg. To avoid errors in interpretation, it is inappropriate to assess the habitual nutrient intake of a nutrient that is intermittently consumed at maximal levels. It is important to assess the iodine intake in consideration of the range of the nutrient intake and of the time period in which the upper limit is exceeded.

Time reduction of vitamin B(6) and inositol assay by using lyophilized Saccharomyces cerevisiae ATCC 9080.

The purpose of this study was to improve the efficiency of the microbiological assays for vitamin B(6) and inositol by using lyophilized cells from Saccharomyces cerevisiae ATCC 9080. The use of lyophilized cells as an inoculum was assessed to avoid time-consuming processes like cell precultivation and washing. The authors also examined the effects of various protectants such as skim milk, lactose, maltose, and trehalose on the assay. The viable cell counts of the lyophilized cells were approximately equal. The standard curves for vitamin B(6) and inositol concentrations obtained using lyophilized cells with maltose and intact cells gave similar linear ranges. Furthermore, the measured vitamin concentrations of the standard reference material 1849 were in the range of the established values. Therefore, lyophilized cells with maltose are potential alternative inocula for the turbidimetric method. This will increase the overall convenience associated with microbiological assays.

Determination of 15 isoflavone isomers in soy foods and supplements by high-performance liquid chromatography.

Soy isoflavone is the generic name for the isoflavones found in soy. We determined the concentrations of 15 soy isoflavone species, including 3 succinyl glucosides, in 22 soy foods and isoflavone supplements by high-performance liquid chromatography (HPLC). The total isoflavone contents in 14 soy foods and 8 supplements ranged from 45 to 735 µg/g and from 1,304 to 90,224 µg/g, respectively. Higher amounts of succinyl glucosides were detected in natto, a typical fermented soy product in Japan; these ranged from 30 to 80 µg/g and comprised 4.1-10.9% of the total isoflavone content. In soy powder, 59 µg/g of succinyl glucosides were detected, equivalent to 4.6% of the total isoflavone content. These data suggest that the total isoflavone contents may be underestimated in the previous studies that have not included succinyl glucosides, especially for Bacillus subtilis -fermented soy food products.

Evaluation of cyanocobalamin in multivitamin tablets and their Standard Reference Material 3280 by HPLC with visible detection.

As a part of the development of an alternative to microbiological assay for vitamin B12, we performed a quantitative analysis of cyanocobalamin (CN-cbl) in a National Institute of Standards and Technology Standard Reference Material (SRM 3280) by HPLC. Using this method, the observed value (4.64 microg/g) of CN-cbl in SRM 3280 was found to be in good agreement with the certified value (4.80 microg/g). The accuracy was over 95%, with a corresponding measurement precision value of 5%. To evaluate the applicability of the method on commercial multivitamin tablets, the method was applied to a variety of these samples. The present method has a good accuracy and precision to evaluate CN-cbl with respect to all of the examined tablets.

Biotin, niacin, and pantothenic acid assay using lyophilized lactobacillus plantarum ATCC 8014.

The purpose of this study was to improve the efficiency of the microbiological assays for biotin, niacin, and pantothenic acid by using lyophilized cells from Lactobacillus plantarum ATCC 8014. The use of lyophilized cells as an inoculum was assessed to avoid time-consuming processes like cell precultivation and washing. The authors also examined the effects of various protectants such as skim milk, sucrose, sorbitol, and trehalose on the assay. The viable cell counts of the lyophilized cells were found to be approximately equal for different protectants. The standard curves for biotin, niacin, and pantothenic acid concentrations obtained using lyophilized cells with sucrose and intact cells gave similar linear ranges. Furthermore, the measured vitamin concentrations of the standard reference material 3280 were in the range of the established values. Therefore, lyophilized cells with sucrose are potential alternative inocula for the turbidimetric method. This will increase the overall convenience associated with microbiological assays.

Estimated average daily intake of antioxidants from typical vegetables consumed in Japan: a preliminary study.

The hydrophilic antioxidant content of 23 vegetables commonly consumed in Japan was assessed by the hydrophilic oxygen radical absorbance capacity (H-ORAC) method to estimate the dietary intake of total antioxidants in Japan. The estimated average H-ORAC value for "typical vegetables" consumed in Japan was 594.3 µmol Trolox equivalent (TE)/100 g. Hence, 2080 µmol TE/d of hydrophilic antioxidants would be ingested when 350 g of vegetables a day are consumed.

Reassessment of antioxidant activity of arbutin: multifaceted evaluation using five antioxidant assay systems.

Arbutin, a practically used skin-lightening agent, has been reported to possess a weak antioxidant activity compared to that of its precursor, hydroquinone. However, its antioxidant activity has not been systematically evaluated. Hence, this study reassessed its activity using five assay systems. Assays were first performed using model radicals, DPPH radical and ABTS(*+). Arbutin showed weak DPPH radical-scavenging activity compared to that of hydroquinone, but showed strong ABTS(*+)-scavenging activity. Its activity by ORAC assay was then evaluated using a physiologically relevant peroxyl radical. Arbutin exerted weak but long-lasting radical-scavenging activity and showed totally the same antioxidant activity as that of hydroquinone. Finally, it was shown that, in two cell-based antioxidant assays using erythrocytes and skin fibroblasts, arbutin exerted strong antioxidant activity comparable or even superior to that of hydroquinone. These findings indicate that the antioxidant activity of arbutin may have been under-estimated and suggest that it acts as a potent antioxidant in the skin.

Evaluation of characteristic deuterium distributions of ephedrines and methamphetamines by NMR spectroscopy for drug profiling.

We have established a method for quantitative analysis of the deuterium contents (D/H) at the phenyl, methine, benzyl, N-methyl and methyl groups of l-ephedrine/HCl, d-pseudoephedrine/HCl and methamphetamine/HCl by 2H NMR spectroscopy. Comparison of the 5 position-specific D/H values of l-ephedrine/HCl and d-pseudoephedrine/HCl prepared by three methods (chemical synthesis, semichemical synthesis, and biosynthesis) showed that chemically synthesized ephedrines and semisynthetic ephedrines have highly specific distributions of deuterium at the methine position and at the benzyl position, compared with the other positions. The classification of several methamphetamine samples seized in Japan in terms of the D/H values at these two positions clearly showed that the methamphetamine samples had been synthesized from ephedrines extracted from Ephedra plants or semisynthetic ephedrines but not from synthetic ephedrine. This isotope ratio analysis method should be useful to trace the origins of seized methamphetamine in Southeast Asia.

Cyclonatsudamine A, a new vasodilator cyclic peptide from Citrus natsudaidai.

A new cyclic heptapeptide, cyclonatsudamine A (1), cyclo (-Gly-Tyr-Leu-Leu-Pro-Pro-Ser-), has been isolated from the peels of Citrus natsudaidai and the structure was elucidated by 2D NMR analysis and chemical degradation. Cyclonatsudamine A (1) relaxed norepinephrine-induced contractions of rat aorta, which may be mediated through the increased release of NO from endothelial cells.

New cyclic peptides from Citrus medica var. sarcodactylis SWINGLE.

Two new cyclic peptides were isolated from the fruit peels of Citrus medica var. sarcodactylis SWINGLE. Their structures were elucidated as cyclo(-Gly-Asp-Leu-Thr-Val-Tyr-Phe-) and cyclo(-Gly-Leu-Pro-Trp-Leu-Ile-Ala-Ala-) by intensive two-dimensional (2D) NMR analysis and chemical evidence.