[Proteome Analysis for Identification of the Origin of Biological Foreign Substances].

We have developed a method for determination of the species of origin of biological foreign substances using proteomics analysis technology. That is, the amino acid sequence of the tryptic digested product of the protein extracted from the foreign substance is determined by high-resolution LC-MS, and the amino acid sequence is collated with a public protein database to determine the origin species of the foreign substance. As a result of testing meat (beef, pork, chicken) and egg (chicken, quail) from known origin as simulated foreign substances, we were able to find species-specific amino acid sequences for each species, suggesting that the developed method is useful for species discrimination of a foreign substances that have been heat-treated with retort, this method is potentially useful to complement DNA analysis, for determination of the species of origin of foreign substances.

[Development of a Method for Estimating the Time Point of Hair Contamination in Retort Pouch Foods].

DNA from hair that has undergone retort pouch sterilization shows considerably more fragmentation. Assessing the extent of DNA fragmentation using a PCR assay could therefore be applied to infer the sterilization history of a contaminated food sample. Such assessments could make it possible to determine whether a food sample had been contaminated by hair during the production process. To determine the extent of retort pouch sterilization, primers specific for the detection of human DNA were designed to give an amplification product of approx 500 bp. Hair was subjected to retort sterilization as a model of contamination, and PCR was performed using the extracted DNA as a template and the primer set for determining retort pouch sterilization. The results showed that no DNA amplification occurred in retort pouch samples, whereas amplification was observed in samples that were unheated, heated in hot water, or heated in a microwave oven. The present method was thus able to specifically detect thermal decomposition of DNA from hair that had undergone retort sterilization, and will be useful for determining whether hair discovered in a retort pouch was responsible for contamination.

[Development of a Method for Simultaneous Analysis of Egg and Milk Major Allergens in Beverage Products Using High-Performance Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry].

A method for simultaneous analysis of egg and milk allergens using LC-QTOF-MS was developed. The proteins measured were α-casein, ß-lactoglobulin, and ovalbumin, which are the main protein allergens in milk and eggs. The proteins were digested using trypsin, and the digests were analyzed by LC-QTOF-MS. Sixteen peaks were detected that confirmed the amino acid sequences of the digests, and a MRM method with high resolution (MRM-HR) using product ions of these peaks was applied for quantification. Next, validation studies were performed using beverage products to which milk and egg standard protein solutions had been added. Good linearity was achieved over the concentration range of 1.25 to 20 µg/g of milk and egg protein, and acceptable reproducibility and accuracy were obtained at 10 µg/g. Moreover, good agreement was also observed between LC-QTOF-MS and ELISA. These findings suggest that this LC-QTOF-MS method may be useful for determining the milk and egg protein contents of beverages.

Functional engineering of human iPSC-derived parasympathetic neurons enhances responsiveness to gastrointestinal hormones.

Food-derived biological signals are transmitted to the brain via peripheral nerves through the paracrine activity of gastrointestinal (GI) hormones. The signal transduction circuit of the brain-gut axis has been analyzed in animals; however, species-related differences and animal welfare concerns necessitate investigation using in vitro human experimental models. Here, we focused on the receptors of five GI hormones (CCK, GLP1, GLP2, PYY, and serotonin (5-HT)), and established human induced pluripotent stem cell (iPSC) lines that functionally expressed each receptor. Compared to the original iPSCs, iPSCs expressing one of the receptors did not show any differences in global mRNA expression, genomic stability, or differentiation capacities of the three germ layers. We induced parasympathetic neurons from these established iPSC lines to assess vagus nerve activity. We generated GI hormone receptor-expressing neurons (CCKAR, GLP1R, and NPY2R-neuron) and tested their responsiveness to each ligand using Ca2+ imaging and microelectrode array recording. GI hormone receptor-expressing neurons (GLP2R and HTR3A) were generated directly by gene induction into iPSC-derived peripheral nerve progenitors. These receptor-expressing neurons promise to contribute to a better understanding of how the body responds to GI hormones via the brain-gut axis, aid in drug development, and offer an alternative to animal studies.

Identification of Acrylamide Adducts Generated during Storage of Canned Milk Coffee.

Since coffee is a significant contributor to the consumption of acrylamide, its reduction is required. Acrylamide is produced during the roasting of coffee beans, but the roasting process is an essential step in determining the taste of coffee. Acrylamide content in coffee has been suggested to decrease by reacting with proteins and/or other substances during storage, but details are unknown. Investigation of acrylamide adducts may contribute to a strategy for acrylamide reduction in coffee. In this study, a stable isotope labeling technique, combined with high-resolution mass spectrometry, allows the identification of acrylamide adducts (3-hydroxypyridine-acrylamide and pyridine-acrylamide) in canned milk coffee. Other acrylamide adducts derived from milk coffee proteins, Lys-acrylic acid and CysSO2-acrylic acid, were identified. During a 4-month storage period, the formation of these four adducts was found to reduce the total content of acrylamide by 75.3% in canned milk coffee. Therefore, endogenous proteins can be used in acrylamide reduction.

5,5-Dimethyl-3-(5-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-1-phenyl-3-(trifluoromethyl)-3,5,6,7-tetrahydro-1H-indole-2,4-dione, a potent inhibitor for mammalian elongase of long-chain fatty acids family 6: examination of its potential utility as a pharmacological tool.

Long-chain fatty acid elongases reside in the endoplasmic reticulum and are responsible for the rate-limiting step of the elongation of long-chain fatty acids. The elongase of long-chain fatty acids (ELOVL) family 6 (ELOVL6) is involved in the elongation of saturated and monosaturated fatty acids. Increased expression of ELOVL6 in ob/ob mice suggests a role for ELOVL6 in metabolic disorders. Furthermore, ELOVL6-deficient mice are protected from high-fat diet-induced insulin resistance, which suggests that ELOVL6 might be a new therapeutic target for diabetes. As reported previously, we developed a high-throughput screening system for fatty acid elongases and discovered lead chemicals that possess inhibitory activities against ELOVL6. In the present study, we examined in detail the biochemical and pharmacological properties of 5,5-dimethyl-3-(5-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-1-phenyl-3-(trifluoromethyl)-3,5,6,7-tetrahydro-1H-indole-2,4-dione (Compound-A), a potent inhibitor of ELOVL6. In in vitro assays, Compound-A dose-dependently inhibited mouse and human ELOVL6 and displayed more than 30-fold greater selectivity for ELOVL6 over the other ELOVL family members. In addition, Compound-A effectively reduced the elongation index of fatty acids of hepatocytes, suggesting that Compound-A penetrates the cell wall and inhibits ELOVL6. More importantly, upon oral administration to mice, Compound-A showed high plasma and liver exposure and potently reduced the elongation index of the fatty acids of the liver. This is the first study to report a potent and selective inhibitor of mammalian elongases. Furthermore, Compound-A seems to be a useful tool to further understand the physiological roles of ELOVL6 and to evaluate the therapeutic potential of an ELOVL6 inhibitor.

High-throughput assay for long chain fatty acyl-CoA elongase using homogeneous scintillation proximity format.

Elongase of very-long-chain fatty acid (Elovl) 6 is a rate-limiting enzyme that is responsible for the elongation of long-chain fatty acids such as palmitoic acid (C16). Elovl6 is abundantly expressed in liver and adipose tissue, and the expression levels in these tissues are up-regulated in obese animals. Furthermore, Elovl6-deficient mice display improved glucose homeostasis and insulin sensitivity, suggesting that Elovl6 might be a potential therapeutic target for metabolic disorders. From the drug discovery point of view, it is critical to establish a high-throughput screening (HTS) assay for the identification of therapeutic agents. Conventional assay methods for fatty acid elongases include an extraction step for respective radioactive products from the reaction mixtures, which is labor-intensive and not feasible for HTS. In this study, we utilized the acyl-coenzyme A (CoA) binding protein (ACBP) as a molecular probe to detect radioactive long-chain acyl-CoA, a direct product of Elovl6. Recombinant ACBP binds stearoyl-CoA but not malonyl-CoA, enabling specific detection of the radioactive product in the homogenous reaction mixture without the liquid extraction step. Finally, combination of ACBP and scintillation proximity assay beads led to specific detection of Elovl6 activity with appropriate window and reproducibility amenable to HTS (signal-to-background noise ratio of approximately 13.0-fold, Z' = 0.85). The assay system described here has the potential to enable identification of small compounds that modify fatty acid elongase activity and assessment of the therapeutic potential of acyl-CoA elongases.

Synthesis, structure-activity relationships, and biological profiles of a dihydrobenzoxathiin class of histamine H(3) receptor inverse agonists.

A series of novel dihydrobenzoxathiin derivatives was synthesized and evaluated as potent human histamine H(3) receptor inverse agonists. After systematic modification of lead 1a, the potent and selective histamine H(3) inverse agonist 1-(3-{4-[(2S,3S)-8-methoxy-3-methyl-4,4-dioxido-2,3-dihydro-1,4-benzoxathiin-2-yl]phenoxy}propyl)pyrrolidine (5k) was identified. Compound 5k showed good pharmacokinetic profiles and brain penetrability in laboratory animals. After 3mg/kg oral administration of 5k, significant elevation of brain histamine levels was observed in rats where the brain H(3) receptor was fully occupied.

Synthesis and evaluation of a novel 2-azabicyclo[2.2.2]octane class of long chain fatty acid elongase 6 (ELOVL6) inhibitors.

A series of novel 2-azabicyclo[2.2.2]octane derivatives was synthesized and evaluated as long chain fatty acid elongase 6 (ELOVL6) inhibitors. Screening of our corporate chemical collections against ELOVL6 resulted in the identification of lead 1. Exploratory chemistry efforts were applied to lead 1 to identify the orally available, potent, and selective ELOVL6 inhibitor 28a.

A highly sensitive determination method for acrylamide in beverages, grains, and confectioneries by supercritical fluid chromatography tandem mass spectrometry.

Acrylamide (AA) analysis is an important topic in food safety. However, it is difficult to rapidly and accurately analyze low concentrations of AA with currently available methods. In the present study, we introduce a highly sensitive method that enables the determination of AA in beverages, grains, and confectioneries by supercritical fluid chromatography tandem mass spectrometry (SFC/MS/MS). The sensitivity of the SFC/MS/MS technique is 11-times higher than that obtained by ultra-high performance liquid chromatography tandem mass spectrometry. We demonstrated that the highly sensitive SFC/MS/MS method was able to quantify low concentrations of AA in beverages (i.e., roasted barley tea and coffee) extracts at less than 10 µg kg-1 level without solid-phase purification. Furthermore, the simplification of the sample preparation procedure provided an improvement in data acquisition time (60 samples per 12 h). In conclusion, the developed analytical system is a potentially useful tool for practical AA determination.

Development of novel 2-[4-(aminoalkoxy)phenyl]-4(3H)-quinazolinone derivatives as potent and selective histamine H3 receptor inverse agonists.

Novel 2-[4-(aminoalkoxy)phenyl]-4(3H)-quinazolinone derivatives were identified as potent human H(3) receptor inverse agonists. After systematic modification of lead 5a, the potent and selective analog 5r was identified. Elimination of hERG K(+) channel and human alpha(1A)-adrenoceptor activities is the main focus of the present study.

Targeted disruption of G protein-coupled bile acid receptor 1 (Gpbar1/M-Bar) in mice.

G protein-coupled bile acid receptor 1 (Gpbar1/M-Bar) is a novel G protein-coupled receptor for bile acid. Tissue distribution and cell-type specificity of Gpbar1 mRNA suggest a potential role for the receptor in the endocrine system; however, the precise physiological role of Gpbar1 still remains to be elucidated. To investigate the role of Gpbar1 in vivo, the Gpbar1 gene was disrupted in mice. In homozygous mice, total bile acid pool size was significantly decreased by 21-25% compared with that of the wild-type mice, suggesting that Gpbar1 contributes to bile acid homeostasis. In order to assess the impact of Gpbar1 deficiency in bile acid homeostasis more precisely, Gpbar1 homozygous mice were fed a high-fat diet for 2 months. As a result, female Gpbar1 homozygous mice showed significant fat accumulation with body weight gain compared with that of the wild-type mice. These findings were also observed in heterozygous mice to the same extent. Although the precise mechanism for fat accumulation in female Gpbar1 homozygous mice remains to be addressed, these data indicate that Gpbar1 is a potential new player in energy homeostasis. Thus, Gpbar1-deficient mice are useful in elucidating new physiological roles for Gpbar1.

Detailed pharmacological characterization of GT-2331 for the rat histamine H3 receptor.

Histamine H(3) receptor antagonists are potential therapeutic agents for cognitive dysfunction, epilepsy, hypersomnia and obesity. GT-2331 (4-[(R,R)-2-(5,5-dimethyl-1-hexynyl)cyclopropyl]-1H-imidazole) was originally identified as a potent histamine H(3) receptor antagonist. However, recent reports demonstrated a complex pharmacology for GT-2331. To further understand the pharmacological profile of GT-2331, we characterized GT-2331 using various in vitro and in vivo assays. In vitro, GT-2331 behaved as a full agonist on adenylyl cyclase inhibition and as a partial agonist on [(35)S]GTPgammaS binding at the recombinant rat histamine H(3) receptor. In contrast, in vivo, GT-2331 had no effect on brain histamine turnover while the histamine H(3) receptor agonist R-alpha-methylhistamine significantly decreased histamine turnover. Furthermore, GT-2331 completely blocked R-alpha-methylhistamine-induced water intake, suggesting that GT-2331 behaves as a full antagonist. Thus, GT-2331 displayed the spectrum of pharmacological activities from full agonism to full antagonism, these observations suggest that histamine H(3) receptor ligands need to be carefully evaluated in various paradigms.

Impaired drinking response in histamine H3 receptor knockout mice following dehydration or angiotensin-II challenge.

Histamine H3 receptors (H3Rs) are presynaptic receptors that negatively regulate the release of histamine. The present study examined the physiological role of H3Rs in drinking behavior. In water-replete rats, intracerebroventricular (i.c.v.) administration of R-alpha-methylhistamine (RalphaMeHA), an H3R agonist, elicited drinking behavior. In contrast, i.c.v. administration of thioperamide, an H3R inverse agonist, significantly attenuated the drinking behavior elicited by either overnight dehydration or i.c.v. administration of angiotensin-II (AT-II). Inhibition of histamine release with alpha-fluoromethylhistidine, an inhibitor of histidine decarboxylase, did not elicit drinking behavior. Moreover, the inhibitory effects of thioperamide on drinking behavior in water-depleted rats were not mimicked by i.c.v. administration of histamine. These results suggest that the predominant effects of H3Rs on drinking behavior are not mediated by the modulation of histamine release. In H3R-deficient (H3RKO) mice, drinking behavior induced by overnight dehydration or i.c.v. administration of AT-II was significantly impaired compared to wild type mice. Collectively, these observations suggest that brain H3Rs play a pivotal role in drinking behavior in response to dehydration and AT-II, and these effects may be largely independent of the modulation of histaminergic tone.

[Structure identification of contaminants in a beverage product by liquid chromatography coupled with quadrupole time-of-flight mass spectrometry].

The contaminants in a beverage product that had been reported to have a strange taste were identified. By comparative analysis with the normal product using liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-QTOF-MS), six unknown compounds were detected in the total ion current chromatograms of the product in question. Detailed analysis of the mass spectra and product ion spectra of these compounds strongly suggested that the compounds were capric acid diethanolamide, lauric acid diethanolamide, myristic acid diethanolamide, lauryl dimethylaminoacetic acid, lauryl sulfate, and lauric acid, all of which are surfactants commonly used as ingredients of household detergents and shampoos. We searched commercially available detergent products to check for the presence of these six surfactants, and identified products that might have been intentionally or unintentionally mixed into the beverage product after opening.

Discovery and characterization of a novel potent, selective and orally active inhibitor for mammalian ELOVL6.

The elongase of long chain fatty acids family 6 (ELOVL6) is a rate-limiting enzyme for the elongation of saturated and monounsaturated long chain fatty acids. ELOVL6 is abundantly expressed in lipogenic tissues such as liver, and its mRNA expression is up-regulated in obese model animals. ELOVL6 deficient mice are protected from high-fat-diet-induced insulin resistance, suggesting that ELOVL6 might be a new therapeutic target for diabetes. We previously identified an indoledione compound, Compound A, as the first inhibitor for mammalian ELOVL6. In this study, we discovered a novel compound, Compound B, and characterized its biochemical and pharmacological properties. Compound B has a more appropriate profile for use as a pharmacological tool compared to Compound A. Chronic treatment with Compound B in model animals, diet-induced obesity (DIO) and KKAy mice, showed significant reduction in hepatic fatty acid composition, suggesting that it effectively inhibits ELOVL6 activity in the liver. However, no improvement in insulin resistance by ELOVL6 inhibition was found in these model animals. Further studies need to address the impact of ELOVL6 inhibition on pharmacological abnormalities in several model animals. This is the first report on pharmacology data from chronic studies using a selective ELOVL6 inhibitor. Compound B appears to be a useful tool to further understand the physiological roles of ELOVL6 and to evaluate the therapeutic potential of ELOVL6 inhibitors.

Identification of a stable chemerin analog with potent activity toward ChemR23.

Chemerin is a novel peptide that was identified as a natural ligand for ChemR23. As it has been reported to be involved in the regulation of immune responses and adipogenesis, chemerin may have a variety of physiological functions. Chemerin is synthesized as a precursor (prochemerin) and is proteolytically activated and inactivated in sequential steps, which control its physiological roles in a coordinated manner. Chemerin-9 (chemerin148-156) was previously identified as the smallest peptide with low nanomolar potency. However, like mature chemerin, chemerin-9 is rapidly degraded and inactivated in plasma, which has limited the use of chemerin-9 in in vivo experiments. In order to identify stable chemerin analogs that facilitate in vivo studies, we synthesized a series of chemerin-9 analogs and examined intrinsic activity and metabolic stability. We identified an agonistic and metabolically stable chemerin-9 analog (d-Tyr(147)-[d-Ser(151), d-Ala(154), Tic(155)]chemerin148-156) that shows enhanced plasma exposure with prolonged half-life in mice upon intraperitoneal administration. Improvement of metabolic stability resulted in a reduction in the plasma free fatty acid levels in fasted mice, which cannot be accomplished by unstable-mouse chemerin-9. This reduction in plasma free fatty acids reflects the anti-lipolysis activity of chemerin-9 and analogs in mouse primary adipocytes. The discovery of a metabolically stable chemerin analog will facilitate investigation of the pharmacological roles of chemerin in vivo. Moreover, this stable chemerin analog might provide new therapeutic approaches to inflammatory diseases such as asthma and metabolic disorders such as obesity and diabetes where ChemR23 activation may be of benefit.

Development of a high-density assay for long-chain fatty acyl-CoA elongases.

We established a convenient assay method for measuring elongation of very long chain fatty acids (ELOVLs) using a Unifilter-96 GF/C plate. The Unifilter GF/C plate preferentially interacts with hydrophobic end products of ELOVLs (i.e., long chain fatty acid), with minimal malonyl-CoA (C2 unit donor for fatty acid elongation) interaction. This new method results in the quick separation and detection of [(14)C] incorporated end products (e.g., [(14)C] palmitoyl-CoA) from reaction mixtures containing excessive amounts of [(14)C] malonyl-CoA. In the Unifilter-96 GF/C plate assay, recombinantly expressed human ELOVLs (i.e., ELOVL1,-2,-3,-5 and -6) displayed appreciable assay windows (>2-fold vs. mock-transfected control), enabling us to conduct comprehensive substrate profiling of ELOVLs. The substrate concentration profile of ELOVL6 in the Unifilter-96 GF/C plate assay is consistent with that obtained from the conventional liquid extraction method, thus, supporting the reliability of the Unifilter-96 GF/C plate assay. We then examined the substrate specificities of ELOVLs in a comprehensive fashion. As previously reported, ELOVL1, -3 and -6 preferably elongated the saturated fatty acyl-CoAs while ELOVL2 and ELOVL5 preferentially elongated the polyunsaturated fatty acyl-CoAs. This further confirms the Unifilter-96 GF/C plate assay reliability. Taken together, our newly developed assay provides a convenient and comprehensive assay platform for ELOVLs, allowing investigators to conduct high density screening and characterization of ELOVLs chemical tools.

Synthesis and evaluation of a novel indoledione class of long chain fatty acid elongase 6 (ELOVL6) inhibitors.

Novel indoledione derivatives were synthesized and evaluated as long chain fatty acid elongase 6 (ELOVL6) inhibitors. Systematic optimization of an indole class of lead 1 led to the identification of potent ELOVL6 selective inhibitors. Representative inhibitor 37 showed sustained plasma exposure and good liver penetrability in mice. After oral administration, 37 potently inhibited ELOVL6 activity in the liver in mice.

Identification and characterization of a selective radioligand for ELOVL6.

ELOVL6, a member of the elongation of very long-chain fatty acids (ELOVL) family, has recently been identified as the rate-limiting enzyme for the elongation of palmitoyl-CoA. ELOVL6 deficient mice are protected from high-fat diet induced insulin resistance, suggesting that ELOVL6 might be a promising target for the treatment of metabolic disorders. Despite the increasing interest in Elovl6 as a therapeutic target, the lack of chemical tools for this enzyme has limited further elucidation of the biochemical and pharmacological properties of ELOVL6. We have identified Compound-A, a potent inhibitor for ELOVL6, by screening our company library and subsequently optimizing hit compounds. Compound-A potently inhibited human and mouse ELOVL6 and displayed >100-fold greater selectivity for ELOVL6 over other ELOVL family members. Consistent with its potent and selective inhibitory activity toward ELOVL6, [(3)H]Compound-A bound to ELOVL6 with high affinity while showing no specific binding to other ELOVL enzymes. The observation that [(3)H]Compound-A bound to ELOVL6 in a palmitoyl-CoA-dependent manner in the absence of malonyl-CoA and NADPH suggests that Compound-A might recognize an enzyme-substrate complex, e.g. an acyl-enzyme intermediate. Collectively, these observations demonstrate that Compound-A and its tritiated form are useful tools for biochemical and pharmacological characterization of ELOVL6.