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Flavones, which are distributed in a variety of plants and foods in nature, possess significant biological activities, including antitumor and anti-inflammatory effects, and are metabolized into glucuronides by uridine 5'-diphosphate (UDP)-glucuronosyltransferase (UGT) enzymes in humans. In this study, apigenin, acacetin, and genkwanin, flavones having hydroxyl groups at C5, C7, and/or C4'positions were focused on, and the regioselective glucuronidation in human liver and intestinal microsomes was examined. Two glucuronides (namely, AP-7G and AP-4'G for apigenin, AC-5G and AC-7G for acacetin, and GE-5G and GE-4'G for genkwanin) were formed from each flavone by liver and intestinal microsomes, except for only GE-4'G formation from genkwanin by intestinal microsomes. The order of total glucuronidation activities was liver microsomes intestinal microsomes for apigenin and acacetin, and liver microsomes intestinal microsomes for genkwanin. The order of CL

Phthalic acid (PA) diesters are widely used in consumer products, as plasticizers, and are ubiquitous environmental pollutants. There is a growing concern about their adjuvant effect on allergic diseases. Although its precise mechanism remains unknown, possible involvement of transient receptor potential ankyrin 1 (TRPA1) has been suggested. Hence, in this study, the activation of human and mouse TRPA1s by a series of PA di- and monoesters was investigated using a heterologous expression system in vitro. Consequently, it was found that monoesters activated human TRPA1, where EC

Introduction Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus causing coronavirus disease 2019 (COVID-19), has been expanding globally since late 2019. SARS-CoV-2, an RNA virus, has a genome sequence that can easily undergo mutation. Several mutated SARS-CoV-2 strains, including those with higher infectivity than others, have been reported. To reduce SARS-CoV-2 transmission, it is crucial to trace its infection sources. Here, we developed a simple, easy-to-use genotyping method to identify SARS-CoV-2 variants using a high-resolution melting (HRM) analysis. Methods We investigated five mutation sites, A23403G, G25563T, G26144T, T28144C, and G28882A, which are known strain determinants according to GISAID clades (L, S, V, G, GH, and GR). Results We first employed synthetic DNA fragments containing the five characteristic sites for HRM analysis. All sequences clearly differentiated wild-type from mutant viruses. We then confirmed that RNA fragments were suitable for HRM analysis following reverse transcription. Human saliva did not negatively affect the HRM analysis, which supports the absence of a matrix effect. Conclusions Our results indicate that this HRM-based genotyping method can identify SARS-CoV-2 variants. This novel assay platform potentially paves the way for accurate and rapid identification of SARS-CoV-2 infection sources.

Bitter taste receptors (TAS2Rs) are expressed by oral cavity cells in mammals and classically function as sensors for bitter compounds. There are 25 functional isoforms of human TAS2Rs, with individual bitter ligands. Each human TAS2R isoform is distributed in several tissues, such as the airway epithelia and gastrointestinal tract, and plays an important role in physiological functions. However, quantification of each isoform is difficult because of highly homologous sequences between some TAS2R isoforms. Therefore, differentiating the isoforms by their expression levels is suitable for clarifying the tissue-specific effects of bitter compounds. In this study, we developed a real-time quantitative PCR (qPCR) method to determine the expression of each TAS2R isoform. Using plasmid standards harboring each isoform, we confirmed that the current assay can quantify the gene expression of each isoform, with negligible interference from other isoforms. In addition, our methods can successfully discriminate between the mRNA expression of each isoform in human cell lines and tissues. Therefore, this qPCR method can successfully quantify the mRNA level of each TAS2R isoform. This method will contribute to a better understanding of the molecular mechanisms underlying the TAS2R ligand-activated signal transduction.

Favipiravir is an antiviral agent effective against several RNA viruses that is converted into an inactive oxidative metabolite (M1), mainly by aldehyde oxidase, in humans. In the present study, the biotransformation of favipiravir into M1 in male and female humans, monkeys, rats, and mice was examined in an in vitro system using liver cytosolic fractions. The kinetics for M1 formation followed the Michaelis-Menten model in all species. The Km , Vmax , and CLint values in humans were 602 µM, 466 pmol/min/mg protein, and 776 nl/min/mg protein in males, respectively, and 713 µM, 404 pmol/min/mg protein, and 567 nl/min/mg protein in females, respectively. Species differences in CLint values were monkeys > humans > mice > rats in both males and females, and the variations for males and females were 120- and 96-fold, respectively. Sex differences in CLint values were males > females in humans and mice, females > males in monkeys and rats, and marked variation (4.3-fold) was noted in mice. This suggests that the roles of aldehyde oxidase in the hepatic metabolism of favipiravir differ extensively depending on the species and sex, and this study will aid in the assessment of the antiviral activities of favipiravir against novel and/or variant viruses.

Bisphenol A (BPA) is an endocrine-disrupting chemical, and is predominantly metabolized into glucuronide in mammals. The present study was conducted in order to examine the hepatic and intestinal g...

Manganese (Mn) poisoning may result in a neurological disorder called manganism. Although the neurotoxic mechanism of Mn is unclear, oxidative stress may be involved based on the interactions between neurotransmitter catecholamines and metals such as iron. Here, we propose a novel mechanism in which Mn oxidizes catecholamines and inhibits cellular transcription. Mn accelerated the oxidation of adrenaline (Ad) and produced adrenochrome (AdC) more effectively than iron. Furthermore, the oxidation of DNA bases increased when Ad, Mn, and iron were present. However, despite the absence of iron, cell viability decreased in the presence of AdC or Ad with Mn, which suggests there is another mechanism independent of oxidative DNA damage. AdC or preincubated Ad with Mn reduced mRNA synthesis in T7 RNA polymerase-driven transcription. RNA synthesis decreased in AdC-treated cells dose-dependently. These results show that Mn disrupts neuronal function via catecholamine oxidation-mediated transcriptional inhibition.

A novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strain, the Omicron variant (Pango lineage B.1.1.529), was identified in South Africa in late September 2021. This variant has multiple spike protein deletions and mutations, with 15 amino acid substitutions detected in the receptor-binding domain (RBD). These RBD substitutions are hypothesized to increase infectivity and reduce antibody affinity, which is supported by recent data showing that the Omicron variant spreads faster than the Delta variant (Pango lineage B.1.617.2). Thus, this increase in infectivity should lead to Omicron being the dominant variant and developing screening tests that discriminate between Omicron and Delta variants is urgently needed. In this study, we successfully developed a novel screening assay using high-resolution melting analysis, in which two genotypes at G446/L452 and S477/T478 RBD were determined (G446S/L452 and S477N/T478K for Omicron; G446/L452R and S477/T478K for Delta). Using synthetic DNA fragments, we confirmed both melting point and melting peak shape of the RBD Omicron variant was distinguishable from those of wild-type and the Delta variant. Although this study was conducted without clinical samples, these results suggest that our high-resolution melting (HRM)-based genotyping method can readily identify the Omicron and Delta variants. This simple method should contribute to the rapid identification of SARS-CoV-2 variants and thus prevent potential widespread infection and inflow of the Omicron variant.

Cyanogenic glycosides in loquat (Eriobotrya japonica) seeds, which are used in so-called health foods, pose a public concern in Japan due to their potential health risks. Several pretreatment methods, such as the steam distillation and Conway microdiffusion methods, have been established for the determination of cyanogenic glycoside concentrations in foods. However, these methods are time-consuming and have extremely low throughput. Therefore, we developed a simple and rapid method, called the purge method, to analyze cyanide compounds in seed-derived food products. Under this method, the aqueous extract of cyanogenic glycosides is treated with β-glucosidase in a midget impinger, after which the liberated cyanide is purged into an absorbing solution. The concentration of cyanide in the adsorbent is then quantified using 4-pyridinecarboxylic acid-pyrazolone reagent. A single-laboratory method validation study was performed using amygdalin at a concentration of 10 ppm as cyanide ion. The validation parameter results (trueness, 83.9%; repeatability, 1.18%; intermediate precision, 4.67%) indicated that the developed method was suitable, precise and accurate. The purge method was used to analyze cyanide concentrations in commercially available food samples. Of the 10 samples tested (loquat seed powder, apricot kernel powder, and plum seed powder), three samples were found to contain cyanogenic glycosides at concentrations of >10 ppm as hydrogen cyanide, with the highest concentration detected being 861 ppm. These results clearly demonstrated the applicability of our method in determining cyanogenic glycosides in seed-derived food samples.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission has been reported worldwide and novel SARS-CoV-2 variants continue to emerge. A novel SARS-CoV-2 strain, the Delta variant (B.1.617.2), is spreading worldwide. The Delta variant has reportedly high infectivity and immune evasion potency. In June 2021, the World Health Organization categorized it as a variant of concern (VOC). Therefore, it is vital to develop tests that can exclusively identify the Delta variant. Here, we developed a rapid screening assay to detect characteristic mutations observed in the Delta variant using high-resolution melting (HRM) analysis. In this assay, we determined L452R and T478K, among which T478K is an identifier of the Delta variant since L452R is seen in other strains (Kappa and Epsilon variants). Additionally, nested PCR-based HRM analysis, which involved RT-PCR (1st PCR) and HRM analysis (2nd PCR), was developed to improve the specificity and sensitivity. Our method discriminated between the L452R mutant and wild-type L452. In addition, HRM analysis distinguished the T478K mutant from the wild-type T478. Seven clinical samples containing the Delta variant were successfully identified as L452R/T478K mutants. These results indicate that this HRM-based genotyping method can identify the Delta variant. This simple method should contribute to rapid identification of the Delta variant and the prevention of infection spread.

Di(2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer that is rapidly metabolized to mono(2-ethylhexyl) phthalate (MEHP), an active metabolite, in mammals. In the present study, the hydrolysis of DEHP by the liver and intestinal microsomes of humans, monkeys, dogs, rats, and mice was examined. The kinetics of liver microsomes fit the Michaelis-Menten model for humans, monkeys, and rats, and the Hill model for dogs and mice. Km or S50 values were similar among species, whereas Vmax exhibited species differences of approximately 9-fold. CLint or CLmax values were in the order of mice > dogs > monkeys ≥ rats > humans. Hydrolytic activity towards DEHP was not detected in the intestinal microsomes of humans or dogs. The kinetics of monkeys, rats, and mice followed the Hill model. In comparisons of the liver microsomes of each species, S50 values were similar, while Vmax and CLmax values (mice > rats > monkeys) were considerably lower (approximately 5–25%). These results suggest that hydrolytic activity towards DEHP in the liver and intestines markedly differ among humans and non-rodent and rodent experimental animals, and imply that species differences are closely associated with the toxicity of DEHP.

Human estrogens prescribed for hormone replacement therapy (HRT) are known to be potent carcinogens. To find safer estrogens, several chlorinated estrogens were synthesized and their carcinogenic potential were determined. A pellet containing either 2-chloro-17β-estradiol (2-ClE2) or 4-chloro-17β-estradiol (4-ClE2) was implanted subcutaneously for 52 weeks into August Copenhagen Irish (ACI) rats, a preferred animal model for human breast cancer. 17β-Estradiol (E2) frequently induced mammary tumors while both 2-ClE2 and 4-ClE2 did not. Their 17α-ethinyl forms, thought to be orally active estrogens, were also synthesized. Neither 2-chloro-17α-ethinylestradiol (2-ClEE2) nor 4-chloro-17α-ethinylestradiol (4-ClEE2) induced tumors. The less carcinogenic effects were supported by histological examination of mammary glands of ACI rats treated with the chlorinated estrogens. A chlorine atom positioned at the 2- or 4-position of E2 may prevent the metabolic activation, resulting in reducing the carcinogenicity. 2-ClE2 and 4-ClE2 administered subcutaneously and 2-ClEE2 and 4-ClEE2 given orally to ovariectomized rats all showed uterotrophic potency, albeit slightly weaker than that of E2. Our results indicate that less carcinogenic chlorinated estrogens retaining estrogenic potential could be safer alternatives to the carcinogenic estrogens now in use for HRT.

Individuals living in an indoor environment are typically exposed to a greater variety of air pollutants than in an outdoor environment. Numerous sources of chemical emissions are found in the indo...

The transferability of phthalic acid esters (PAEs) and other plasticizers, from model polyvinyl chloride (PVC) sheets to the skin of 11 subjects was assessed by measuring the amount of substance transferred using PVC sheets containing PAEs and alternative plasticizers of different types and contents. For all subjects, the transferred amount, from sheets containing 28 wt% PAE or from mixed sheets containing 14 wt% each of di (2-ethylhexyl) phthalate (DEHP) and other PAE, was greater than that from sheets containing 15 wt% each of PAE or alternative plasticizer only. A comparison of the transferability of five types of PAE showed that transfer tended to occur more readily as the

Estrogen is reported to be involved in mammary tumorigenesis. To unveil metabolic signatures for estrogen-induced mammary tumorigenesis, we carried out serum metabolomic analysis in an estrogen-induced mammary tumor model, female August Copenhagen-Irish/Segaloff (ACI/Seg) rats, using liquid chromatography-mass spectrometry. In contrast to the control group, all rats with an implanted 17β-estradiol (E2) pellet developed mammary tumors during this experiment. E2 treatment significantly suppressed body weight gain. But no significant differences in food consumption were observed between the two groups, suggesting that metabolic alteration depended on E2 treatment. Serum metabolomic analysis detected 116 features that were statistically different (p 0.01) between the groups. Quantitation analysis revealed that several phospholipids such as phosphatidylcholines and lysophosphatidylcholines (LPCs) were identified as significantly different metabolites. E2-treated rat serum stimulated the proliferation of human breast cancer MDA-MB-231 cells. In addition, the proliferation effect was diminished by pretreating cells with either autotaxin inhibitor or antagonist for lysophosphatidic acid receptor whose ligands are metabolites of LPCs via autotaxin-mediated hydrolysis. In summary, our results suggest that not only are phospholipids potential biomarkers for mammary tumors but importantly, LPCs themselves could be associated with E2-induced mammary tumorigenesis in female ACI/Seg rats.

Currently, indoor air quality guidelines for formaldehyde and acetaldehyde are set by the Ministry of Health, Labour and Welfare of Japan. Aldehydes are widely used in adhesives and preservatives, and exposure to these compounds via indoor air is a matter of concern. Considering that contact with indoor air is part of daily life, evaluation of indoor air quality is extremely important. 2,4-Dinitrophenylhydrazine (DNPH) derivatization is widely used for quantitative analysis of aldehydes. A certified reference material with traceability to the International System of Units (SI) is required for this method. However, currently, there are no certified reference materials available for aldehyde-DNPH derivatives, which means that the quantified values obtained by this method are not sufficiently reliable. In this study, we determined the actual content and purity of commercially available aldehyde-DNPH derivatives using 1H-quantitative NMR (qNMR), which can be measured with SI-traceability. Although the commercial DNPH derivatives of formaldehyde and acetaldehyde were low concentration solutions, we were able to determine their purities using 1H-qNMR. Furthermore, we were able to separate and quantify the acetaldehyde isomers generated by the derivatization reaction. In conclusion, it is possible to obtain highly accurate results using 1H-qNMR with commercially available reagents that are not certified metrologically.

Naringenin, a flavanone found in citrus fruits, is mainly metabolized into glucuronide(s) by UDP-glucuronosyltransferase (UGT) enzymes in mammals. In the present study, the glucuronidation of naringenin in the liver and intestine microsomes of humans, monkeys, rats, and mice was examined. The kinetics of 7-glucuronidation in human liver and intestine microsomes followed the Michaelis-Menten model. Kinetics in mouse liver and intestine microsomes also followed the Michaelis-Menten model, whereas those in monkey and rat liver microsomes fit the biphasic model. Kinetics in monkey and rat intestine microsomes fit the Michaelis-Menten and substrate inhibition models, respectively. CLint values were mice > monkeys > rats > humans for liver microsomes, and mice > rats > monkeys > humans for intestine microsomes. In 4´-glucuronidation, activities in human liver microsomes and monkey liver and intestine microsomes were negligible or very low. Kinetics in rat and mouse liver microsomes followed the biphasic and Michaelis-Menten models, respectively. CLint values were rats > mice for liver microsomes, and rats > mice > humans for intestine microsomes. These results suggest that the metabolic abilities and regioselectivity of UGT enzymes toward naringenin in the liver and intestines generally differ between primates and rodents.

Phthalates, known as reproductive toxicants and endocrine disruptors, are widely used as plasticizers in polyvinyl chloride products. The present study was conducted for risk identification of dermal exposure to phthalates. When dibutyl phthalate was applied to the skin of hairless rats and humans, only monobutyl phthalate appeared through the skin, and the permeability of the skin was higher than that after the application of the monoester directly. The inhibition of skin esterases made the skin impermeable to the metabolite following dermal exposure to dibutyl ester, whereas removal of the stratum corneum from the skin did not change the skin permeation behavior. Similar phenomena were observed for benzyl butyl phthalate. The skin permeability of monobenzyl phthalate was higher than that of monobutyl phthalate in humans, although the reverse was observed in rats. Species difference in skin permeation profile corresponded to the esterase activity of the skin homogenate. Di(2-ethylhexyl) phthalate, which was not metabolized by esterases in the skin, was not transported across the skin. These results suggest that highly lipophilic phthalates may be transported easily across the stratum corneum lipids. The water-rich viable layer may become permeable to these phthalates by their metabolism into monoesters, which are relatively hydrophilic. Skin metabolism is essential to the percutaneous absorption of phthalates. Because esterase activity has large inter-individual differences, further study will be needed for individual risk identification of dermal exposure to phthalates.

Selenium (Se) is an essential trace element and is regarded as a protective agent against cancer. In particular, antioxidant effects of selenoenzymes contribute to cancer prevention. Se can also produce reactive oxygen species and, thereby, exert cancer-selective cytotoxicity. Selenodiglutathione (SDG) is a primary Se metabolite conjugated to two glutathione (GSH) moieties. SDG increases intracellular Se accumulation and is more toxic than selenous acid (H2SeO3), but the mechanisms for importing Se compounds into cells are not fully understood. Here, we propose a novel mechanism for importing Se, in the form of SDG. Cellular intake of Se compounds was assessed based on Se accumulation, as detected by ICP-MS. SDG incorporation was decreased in the presence of thiols (GSH, cysteine or their oxidized forms, GSSG and cystine), whereas H2SeO3 uptake was increased by addition of GSH or cysteine. Cellular SDG uptake was decreased by pretreatment with specific inhibitors against gamma-glutamyl transpeptidase (GGT) or the cystine/glutamate antiporter (system xc-). Furthermore, siRNA against xCT, which is the light chain component of system xc-, significantly decreased SDG incorporation. These data suggest an involvement of SDG in Se incorporation, with SDG processed at the cell surface by GGT, leading to formation of selenodicysteine which, in turn, is likely to be imported via xCT. Because GGT and xCT are highly expressed in cancer cells, these mechanisms mediated by the cystine transporter might underlie the cancer-selective toxicity of Se. In addition, the system described in our study appears to represent a physiological transport mechanism for the essential element Se.

Individuals living in general indoor environments are exposed to a greater variety of chemical pollutants, albeit at lower concentrations, compared with industrial workers in occupational environments. These pollutants can result in a variety of adverse health effects, including those affecting the respiratory, neurological, reproductive, dermatologic, and cardiovascular systems. In Japan, indoor air quality guidelines have been established for 13 chemicals since 1997, and these developments have continued on the basis of scientific discussions in the Committee on Indoor Air Pollution (CIAP) that was set up by the Ministry of Health, Labour and Welfare. However, the types and concentrations of these pollutants have been observed to be inconsistent over time due to lifestyle changes and the development of novel household products and building materials. Therefore, continuing the monitoring of indoor chemicals and the development of indoor air quality guidelines for substances that pose potential high health risks are essential for the protection of public health. In indoor environments, there are multiple media by which humans come in contact with indoor chemicals and multiple exposure pathways that can affect human health, particularly for semi-volatile organic compounds (SVOCs). This is defined as aggregate exposure. Furthermore, combined exposure to multiple low-level pollutants occurs in indoor environments. In this article, a comprehensive overview of the indoor air quality guidelines in Japan and assessment approaches for developing indoor air quality guidelines is provided. In addition, future issues facing approaches for indoor chemicals, including aggregate exposure to SVOCs and combined exposure to multiple pollutants with common toxicological effects in indoor environments, are discussed.

Fluorination preventing metabolic hydroxylation of 17β-estradiol (E2) was applied to investigate the mechanisms underlying estrogen-induced carcinogenesis. Either 2-fluoro-17β-estradiol (2-FE2) or 4-fluoro-17β-estradiol (4-FE2) was administered subcutaneously for 52 weeks to August Copenhagen Irish (ACI) rats, the preferred animal model for human breast cancer. 4-FE2 induced frequent mammary tumors whereas 2-FE2 did not. The cumulative incidence of mammary tumors in rats treated with 4-FE2 was comparable to that observed with E2. The carcinogenic results were supported by histological examination of mammary glands of fluorinated estrogen-treated ACI rats. To evaluate the estrogenic potential of the fluorinated estrogens, 2-FE2 or 4-FE2 was administrated subcutaneously to ovariectomized rats. Both 4-FE2 and 2-FE2 showed high uterotrophic potency. Our results indicate that estrogenic potential may not be the sole factor driving mammary tumorigenesis. Since fluorination inhibits metabolic hydroxylation of E2 at the substituted position, the carcinogenic effect may occur through the metabolic activation of 2-hydroxylated E2, in combination with the compound's estrogenic potency.

Kampo medicines containing Ephedra Herb (EH) such as eppikajutsubuto and makyoyokukanto are used to treat myalgia, arthralgia, and rheumatism. The analgesic effects of these Kampo medicines are attributed to the anti-inflammatory action of EH. However, the molecular mechanism of the analgesic effect of EH remains to be clarified. In this study, the effects of EH extract (EHE) on transient receptor potential vanilloid 1 (TRPV1), a nonselective ligand-gated cation channel, which plays an essential role in nociception on sensory neurons, were investigated using mTRPV1/Flp-In293 cells (stable mouse TRPV1-expressing transfectants). Administration of EHE increased the intracellular Ca2+ concentration in these cells, which was inhibited by the TRPV1 antagonist, N-(4-tert-butylphenyl)-1,2-dihydro-4-(3-chloropyridine-2-yl) tetrahydropyrazine-1-carboxamide (BCTC), indicating that EHE activated TRPV1. Examination of EHE-induced nociceptive pain in vivo revealed that an intradermal (i.d.) injection of EHE into the hind paw of mice induced paw licking, a pain-related behavior, and that the extract increased paw licking times in a dose-dependent manner. The EHE-induced paw licking was also inhibited by BCTC. An i.d. injection of EHE 30 min before administration of capsaicin decreased capsaicin-induced paw licking times. Similarly, oral administration of the extract also suppressed capsaicin-induced paw licking, without affecting the physical performance of the mice. These results suggest that EHE suppresses capsaicin-induced paw licking by regulating TRPV1 activity. Thus, the antinociceptive effects of EHE seem to be produced by its direct action on sensory neurons through TRPV1. Electronic supplementary material The online version of this article (doi:10.1007/s11418-016-1034-9) contains supplementary material, which is available to authorized users.

4-tert-Octylphenol (4-tOP) is an endocrine-disrupting chemical. It is mainly metabolized into glucuronide by UDP-glucuronosyltransferase (UGT) enzymes in mammals. In the present study, the glucuronidation of 4-tOP in humans, monkeys, rats, and mice was examined in an in vitro system using microsomal fractions. The kinetics of 4-tOP glucuronidation by liver microsomes followed the Michaelis–Menten model for humans and monkeys, and the biphasic model for rats and mice. The K m, V max, and CL int values of human liver microsomes were 0.343 µM, 11.6 nmol/min/mg protein, and 33.8 mL/min/mg protein, respectively. The kinetics of intestine microsomes followed the Michaelis–Menten model for humans, monkeys, and rats, and the biphasic model for mice. The K m, V max, and CL int values of human intestine microsomes were 0.743 µM, 0.571 nmol/min/mg protein, and 0.770 mL/min/mg protein, respectively. The CL int values estimated by Eadie–Hofstee plots were in the order of mice (high-affinity phase) (3.0) > humans (1.0) ≥ monkeys (0.9) > rats (high-affinity phase) (0.4) for liver microsomes, and monkeys (10) > mice (high-affinity phase) (5.6) > rats (1.4) > humans (1.0) for intestine microsomes. The percentages of the CL int values of intestine microsomes to liver microsomes were in the order of monkeys (27 %) > rats (high-affinity phase in liver microsomes) (7.9 %) > mice (high-affinity phase in liver and intestine microsomes) (4.2 %) > humans (2.3 %). These results suggest that the metabolic abilities of UGT enzymes expressed in the liver and intestine toward 4-tOP markedly differ among species and imply that species differences are strongly associated with the toxicities of alkylphenols.

Mono(2-ethylhexyl) phthalate (MEHP) is an active metabolite of di(2-ethylhexyl) phthalate (DEHP), which is an endocrine-disrupting chemical. In the present study, MEHP glucuronidation in humans was studied using recombinant UDP-glucuronosyltransferases (UGTs) and microsomes of the liver and intestine. Among the recombinant UGTs examined, UGT1A3, UGT1A7, UGT1A8, UGT1A9, UGT1A10, UGT2B4, and UGT2B7 glucuronidated MEHP. The kinetics of MEHP glucuronidation by UGT1A3, UGT1A7, UGT1A8, UGT1A10, UGT2B4, and UGT2B7 followed the Michaelis–Menten model, whereas that by UGT1A9 fit the negative allosteric model. CLint values were in the order of UGT1A9 > UGT2B7 > UGT1A7 > UGT1A8 ≥ UGT1A10 > UGT1A3 > UGT2B4. The kinetics of MEHP glucuronidation by liver microsomes followed the Michaelis–Menten model. Diclofenac (20 µM) and raloxifene (20 µM) decreased CLint values to 43 and 36 % that of native microsomes, respectively. The kinetics of MEHP glucuronidation by intestine microsomes fit the biphasic model. Diclofenac (150 and 450 µM) decreased CLint values to 32 and 13 % that of native microsomes for the high-affinity phase, and to 28 and 21 % for the low-affinity phase, respectively. Raloxifene (2.5 and 7.0 µM) decreased CLint values to 35 and 4.1 % that of native microsomes for the high-affinity phase, and to 48 and 53 % for the low-affinity phase, respectively. These results suggest that MEHP glucuronidation in humans is catalyzed by UGT1A3, UGT1A9, UGT2B4, and/or UGT2B7 in the liver, and by UGT1A7, UGT1A8, UGT1A9, UGT1A10, and/or UGT2B7 in the intestine, and also that these UGT isoforms play important and characteristic roles in the detoxification of DEHP.

Background:In the past decades, indoor air pollution has become a major public health concern. Therefore, Japan has established indoor air quality guidelines for 13 chemicals, including formaldehyd...

Daidzein, one of the major soy isoflavones, has a number of beneficial bioactivities for human health. It is mainly metabolized into 7- and/or 4′-glucuronides by UDP-glucuronosyltransferase (UGT) enzymes in mammals, including humans. The present study was conducted to examine the regioselective glucuronidation of daidzein at the 7- and 4′-hydroxyl groups in the liver and intestinal microsomes of humans, monkeys, rats, and mice. Daidzein glucuronidation activities at substrate concentrations of 1.0–200 µM were assessed, and Eadie–Hofstee plots were constructed. The kinetics for 7- and 4′-glucuronidation in the liver microsomes fit the Michaelis–Menten model, except for an atypical model for 7-glucuronidation in rats and a biphasic model for 4′-glucuronidation in monkeys. These kinetics in the intestinal microsomes followed the Michaelis–Menten model, except for a biphasic model for 7-glucuronidation in mice. The CLint values for 7-glucuronidation were in the order of monkeys (49) ≫ rats (5.3) > humans (1.0) > mice (0.7) for liver microsomes, and rats (2.4) ≥ monkeys (2.2) > humans (1.0) ≥ mice (0.8) for intestinal microsomes. On the other hand, the CLint values for 4′-glucuronidation were in the order of monkeys (4.0) > mice (1.0) ≈ humans (1.0) > rats (0.4) for liver microsomes, and humans (1.0) ≫ monkeys (0.08) ≥ mice (0.07) > rats (0.05) for intestinal microsomes. These results demonstrated that the metabolic abilities of UGT enzymes toward daidzein in the liver and intestines markedly differed among humans, monkeys, rats, and mice, and suggest that species and regioselective differences are closely associated with the bioactivities of soy isoflavones.

A variety of chemicals have been used in a wide range of indoor materials, such as wallpaper and furniture, and some of them are released into the indoor air. The level of consumption as well as the diversity of these chemicals has been increasing. The particle size of the materials in the air is known to affect the depth of human exposure, e.g., particles >10 μm can only reach the nasal cavity, whereas particles 2.5-10 μm can reach the respiratory tract and particles 10 μm) and a C18 solid-phase extraction disk to capture chemicals that exist in a gas phase in indoor air. Each of the chemicals in the three particulate phases and single gas phase was extracted by acetone and measured separately using GC/MS. Of the 54 compounds tested, 37 were detected in the indoor air samples. The highest concentration observed was that of 2-ethyl-1-hexanol (5.1 μg/m3), which was detected in samples from all 21 houses. The 37 compounds were captured in the four fractions at different rates roughly based on their molecular sizes. Compounds with a smaller molecular size were commonly detected as a gas phase, whereas compounds with a larger molecular size were detected as one or more of the three particulate phases in the indoor air samples. Among the three particulate phases, many of the compounds were detected from the filter capturing the smallest (

To construct a model formula to evaluate the thermogenetic effect of ginger (Zingiber officinale Roscoe) from the ingredient information, we established transient receptor potential vanilloid subtype 1 (TRPV1)-stimulating activity prediction models by using a partial least-squares projections to latent structures (PLS) regression analysis in which the ingredient data from liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and the stimulating activity values for TRPV1 receptor were used as explanatory and objective variables, respectively. By optimizing the peak extraction condition of the LC-HRMS data and the data preprocessing parameters of the PLS regression analysis, we succeeded in the construction of a TRPV1-stimulating activity prediction model with high precision ability. We then searched for the components responsible for the TRPV1-stimulating activity by analyzing the loading plot and s-plot of the model, and we identified [6]-gingerol (1) and hexahydrocurcumin (3) as TRPV1-stimulating activity components.

4-tert-Octylphenol (4-tOP) is an endocrine-disrupting chemical. It is mainly metabolized into glucuronide by UDP-glucuronosyltransferase (UGT) enzymes in humans. The purpose of this study was to assess inter-individual variability in and the possible roles of UGT isoforms in hepatic 4-tOP glucuronidation in the humans. 4-tOP glucuronidation activities in the liver microsomes and recombinant UGTs of humans were assessed at broad substrate concentrations, and kinetics were analyzed. Correlation analyses between 4-tOP and diclofenac or 4-hydroxybiphenyl activities in pooled and individual human liver microsomes were also performed. Typical CLint values were 17.8 mL/min/mg protein for the low type, 25.2 mL/min/mg protein for the medium type, and 47.7 mL/min/mg protein for the high type. Among the recombinant UGTs (13 isoforms) examined, UGT2B7 and UGT2B15 were the most active of catalyzing 4-tOP glucuronidation. Although the K m values of UGT2B7 and UGT2B15 were similar (0.36 and 0.42 µM, respectively), the CLint value of UGT2B7 (6.83 mL/min/mg protein) >UGT2B15 (2.35 mL/min/mg protein). Strong correlations were observed between the glucuronidation activities of 4-tOP and diclofenac (a probe for UGT2B7) or 4-hydroxybiphenyl (a probe for UGT2B15) with 0.79-0.88 of Spearman correlation coefficient (r s) values. These findings demonstrate that 4-tOP glucuronidation in humans is mainly catalyzed by hepatic UGT2B7 and UGT2B15, and suggest that these UGT isoforms play important and characteristic roles in the detoxification of 4-tOP.

Various plasticizers and flame retardants are contained in building materials and furniture produced for indoor environments. However, some of these material inclusions have been reported to cause endocrine-disrupting and mucosa-irritating effects. Because of the local climate, buildings in Sapporo are better insulated against cold weather than those in many other areas in Japan. In this study, we measured 59 compounds, including plasticizers (phthalates, adipates, and others) and flame retardants (organo-phosphates and brominated compounds), from indoor air samples from six houses in Sapporo. These compounds were measured separately in the gas phase and the particle phase using a two-stage cartridge equipped with a quartz fiber filter (1 μm mesh) and C18 solid-phase extraction disk for sampling and analyzed by GC/MS and LC/MS/MS (for the detection of brominated flame retardants). Among the 59 compounds measured in this study, 34 compounds were detected from the indoor air of the six houses. The highest concentration among the 34 compounds found in a newly built house was 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TXIB) at 20.8 μg/m3. Di(2-ethyl-1-hexyl)terephthalate (DEHT), which has been used in recent years as an alternative to di(2-ethyl-1-hexyl)phthalate (DEHP), was found in all six houses, although at low concentrations ranging from 0.005 to 0.027 μg/m3. To our knowledge, this is the first report of DEHT in indoor air in Japan. Among the compounds detected in this study, those with lower molecular weights tended to be captured in the C18 solid-phase extraction disk rather than in the quartz fiber filter. These results suggest that compounds with higher volatility exist preferentially in the gas phase, whereas compounds with lower volatility exist preferentially in the particulate phase in indoor air.

Advances in the synthesis and utilization of new chemical compounds have led to improvements in our daily lives. However, new chemicals may be both beneficial and toxic. Thus, exposure to these new compounds should be restricted in an attempt to limit their potential toxicities. We predicted the safety of three biocides (p-cresol, diazinon and resmethrin) by comparing their skin permeability coefficients and desquamation rate (the counter flux of permeability coefficient for chemical compounds induced by skin turnover) following skin exposure. In vitro skin permeation experiments revealed that the permeability coefficients of diazinon and resmethrin were smaller than the desquamation rate; therefore, these biocides could not permeate the skin, which resulted in very low skin concentrations of these compounds. On the other hand, the skin concentration of p-cresol was high because of its higher permeability coefficient than the desquamation rate. Furthermore, low in vitro cell viability was reported for skin exposed to p-cresol. These results in the present study indicate that the method described herein is useful for predicting the toxicities of chemicals following their topical exposure., 「J-STAGE」で公開

We conducted a national-scale survey on the haloacetic acids (HAAs) in the typical components of the Japanese diet. Combined with the findings of a previous study on multi-route HAA exposure, we estimated the actual relative contributions of drinking water ingestion to total HAA exposure and in this paper we discuss the necessary allocation factors for setting drinking water quality standard values of HAAs. The currently applied allocation (20%) was found to be unrealistically low and in need of appropriate adjustment. After determining the probability distribution of the relative contribution of each HAA, the rounded values corresponding to 0.05 and 0.1 cumulative probabilities were recommended for dichloroacetic acid (40%), trichloroacetic acid (30%), bromochloroacetic acid (30%) and bromodichloroacetic acid (60%) as their allocation factors. The direction of future investigations is discussed along with an overview of various sources of uncertainty. Ingestion exposure via diet and daily drinking water consumption were identified as priority factors.

Raloxifene is an antiestrogen marketed for the treatment of osteoporosis. The major metabolic pathway of raloxifene is glucuronidation at 6- and/or 4′-positions, which is mainly catalyzed by UDP-glucuronosyltransferase 1A8 (UGT1A8) expressed in extrahepatic tissues such as the small intestine and colon. Two non-synonymous allelic variants, termed UGT1A8 * 2 (518C > G, A173G) and UGT1A8 * 3 (830G>A, C277Y), have been found in Caucasian, African–American and Asian populations. In this study, the effect of amino acid substitutions in UGT1A8 on raloxifene glucuronidation was studied using recombinant UGT1A8 enzymes of wild-type (UGT1A8.1) and variant UGT1A8 (UGT1A8.2 and UGT1A8.3) expressed in Sf9 cells. Raloxifene 6- and 4′-glucuronidation by UGT1A8.1 exhibited negative allosteric kinetics. The K m and V max values of UGT1A8.1 were 15.0 μM and 111 pmol/min/mg protein for 6-glucuronidation, and 9.35 μM and 232 pmol/min/mg protein for 4′-glucuronidation, respectively. The kinetics of raloxifene 6-glucuronidation by UGT1A8.2 was positive allosteric, whereas the kinetics of raloxifene 4′-glucuronidation was negative allosteric. The S 50 value of raloxifene 6-glucuronidation was markedly low (1.2%) compared with the K m value of UGT1A8.1, and the K m value for raloxifene 4′-glucuronidation was 29% that of UGT1A8.1. The V max value for raloxifene 6-glucuronidation by UGT1A8.2 was comparable to that of UGT1A8.1, whereas the V max value for raloxifene 4′-glucuronidation was significantly lower (54%) than that of UGT1A8.1. The activities of raloxifene 6- and 4′-glucuronidation in UGT1A8.3 were markedly lower than those of UGT1A8.1. In mycophenolic acid glucuronidation, the kinetics by wild-type and variant UGT1A8s fitted the Michaelis–Menten model. The K m and V max values of UGT1A8.1 were 123 μM and 4820 pmol/min/mg protein, respectively. The K m and V max values of UGT1A8.2 were comparable to those of UGT1A8.1. The K m value of UGT1A8.3 was similar to that of UGT1A8.1, whereas the V max value was reduced to 2.4% of UGT1A8.1. These findings suggest that A173G and C277Y substitutions of UGT1A8 change the metabolic ability toward raloxifene, and that the polymorphic alleles of UGT1A8 may influence the clinical response and bioavailability of medicines metabolized mainly by UGT1A8.

Uridine diphosphate (UDP)-glucuronosyltransferase 1A1 (UGT1A1) plays important roles in the glucuronidation of various drugs and endogenous substances. Minipigs have been used as experimental animals in pharmacological and toxicological studies, because many of their physiological characteristics are similar to those of humans. In this study, the similarities and differences in enzymatic properties of UGT1A1 between humans and minipigs were precisely identified. Minipig UGT1A1 (mpUGT1A1) cDNA was firstly cloned by the rapid amplification of cDNA ends (RACE) method, and the corresponding protein as well as human UGT1A1 (hUGT1A1) enzyme was expressed in insect cells. Then the kinetics of estradiol at 3-hydroxy position (E-3OH) and 7-ethyl-10-hydroxycamptothecin (SN-38) glucuronidation by recombinant UGT1A1s as well as human and minipig liver microsomes were analyzed. The homology between mpUGT1A1 and hUGT1A1 at the amino acid level was 80.9%. E-3OH and SN-38 glucuronidation by recombinant hUGT1A1 and mpUGT1A1 showed allosteric sigmoidal kinetics. The CL value (29.1 µL/min/mg protein) for E-3OH glucuronidation of mpUGT1A1 was significantly higher (1.4-fold) than that of hUGT1A1, whereas the CL value (0.83 µL/min/mg protein) for SN-38 glucuronidation was significantly lower (27%) than that of hUGT1A1; however, the kinetic models and parameter levels for E-3OH and SN-38 glucuronidation by human and minipig liver microsomes did not parallel those in the respective species. These findings suggest that the enzymatic properties of UGT1A1 are considerably different between humans and minipigs. The information on species differences in UGT1A1 function gained in this study should help with in vivo extrapolation of xenobiotic metabolism and toxicity.