Preclinical pharmacokinetics and metabolism of MAK683, a clinical stage selective oral embryonic ectoderm development (EED) inhibitor for cancer treatment.

MAK683 (N-((5-fluoro-2,3-dihydrobenzofuran-4-yl)methyl)-8-(2-methylpyridin-3-yl)-[1,2,4]triazolo[4,3-c]pyrimidin-5-amine) is a potent and orally bioavailable EED inhibitor for the potential treatment in oncology. Pharmacokinetics (PK) in preclinical species are characterised by low to moderate plasma clearances, high oral exposure, and moderate to high oral bioavailability at the dose of 1-2 mg/kg.A species comparison of the metabolic pathways of MAK683 has been made using [14C]MAK683 incubations with liver microsomes and hepatocytes from rat, dog, cynomolgus monkey, and human. Overall, the in vitro hepatic metabolism pathway of MAK683 in all five species was very complex. A total of 60 metabolites with 19 metabolites >1.5% of the total integrated area in the radiochromatogram of at least one species were identified in five species (rat, mouse, dog, monkey, and human).The primary in vitro hepatic oxidative metabolism pathway identified in humans involved 2-hydroxylation of the dihydrofuran ring to form alcohol (M28), which was in a chemical equilibrium favouring the formation of its aldehyde form. The aldehyde was then oxidised to the carboxylic acid metabolite (M26) or reduced to the O-hydroxyethylphenol (M29). N-dealkylation (M1), 3-hydroxylation of the dihydrofuran ring (M27), N-oxidation of the pyridine moiety (M53), and sulphate conjugation of M28 to form M19 were also important biotransformation pathways in human hepatocytes. The above major human hepatic metabolic pathways were also observed across the animal species (rat, mouse, dog, and monkey) mostly providing precursors for the formation of other metabolites via further oxygenation, glucuronidation, and sulphation pathways.No human-specific metabolites were observed. In addition, in vivo biotransformation was also conducted in bile-duct cannulated (BDC) rat. The metabolism in BDC rat was similar to those observed the in vitro hepatocytes.

Metabolism of c-Met Kinase Inhibitors Containing Quinoline by Aldehyde Oxidase, Electron Donating, and Steric Hindrance Effect.

Some quinoline-containing c-Met kinase inhibitors are aldehyde oxidase (AO) substrates. 3-Substituted quinoline triazolopyridine analogs were synthesized to understand the electron-donating and steric hindrance effects on AO-mediated metabolism. Metabolic stability studies for these quinoline analogs were carried out in liver cytosol from mice, rats, cynomolgus monkeys, and humans. Several 3-N-substituted analogs were found to be unstable in monkey liver cytosolic incubations (half-life, <10 minutes), and five of them (63, 53, 51, 11, and 71) were chosen for additional mechanistic studies. Mono-oxygenation on the quinoline ring was identified by liquid chromatography tandem mass spectrometry. Metabolite formation was inhibited by the AO inhibitors menadione and raloxifene, but not by the xanthine oxidase inhibitor allopurinol. It was found that small electron-donating groups at the 3-quinoline moiety made the analogs more susceptible to AO metabolism, whereas large 3-substituents could reverse the trend. Although species differences were observed, this trend was applicable to all species tested. Small electron-donating substituents at the 3-quinoline moiety increased both affinity (decreased Michaelis constant) and V max maximum velocity toward AO in kinetic studies, whereas large substituents decreased both parameters probably as a result of steric hindrance. Based on our analysis, a common structural feature with high AO liability was proposed. Our finding could provide useful information for chemists to minimize potential AO liability when designing quinoline analogs.

The Revision of Aluminum-containing Food Additive Provisions in China.

The aim of this study was to revise the provisions for aluminum-containing food additives in GB 2760-2011 (The National Food Safety Standard for Use of Food Additives), in order to reduce aluminum exposure among the Chinese population. According to the latest risk assessment results of JECFA and China on aluminum and the actual use of aluminum-containing food additives in certain products, the aluminum-containing food additive-related provisions in GB 2760-2011 were revised. Those revisions included narrowing down the applicable food categories and adjusting the maximum use level of aluminum potassium sulfate and aluminum ammonium sulfate, repealing nine aluminum-containing food additives in puffed food and repealing the use of sodium aluminum phosphate, sodium aluminosilicate and starch aluminum octenylsuccinate in all food. After revision of the use of aluminum food additive provisions, the weekly dietary intake of aluminum in the Chinese population can be reduced to a safe level.

Rapid and Sensitive Chemiluminescent Enzyme Immunoassay for the Determination of Neomycin Residues in Milk.

Immunoassays greatly contribute to veterinary drug residue analysis. However, there are few reports on detecting neomycin residues by immunoassay. Here, a rapid and sensitive chemiluminescent enzyme immunoassay (CLIEA) was successfully developed for neomycin residue analysis. CLIEA demonstrated good cross-reactivity for neomycin, and the IC50 value was 2.4 ng/mL in buffer. The average recovery range was 88.5%-105.4% for spiked samples (10, 50, and 100 µg/kg), and the coefficient of variation was in the range of 7.5%-14.5%. The limit of detection of CLEIA was 9.4 µg/kg, and this method was compared with the liquid chromatography-tandem mass spectrometry method using naturally contaminated samples, producing a correlation coefficient of >0.95. We demonstrate a reliable CLIEA for the rapid screening of neomycin in milk.

Risk analysis of sulfites used as food additives in China.

This study was to analyze the risk of sulfites in food consumed by the Chinese people and assess the health protection capability of maximum-permitted level (MPL) of sulfites in GB 2760-2011. Sulfites as food additives are overused or abused in many food categories. When the MPL in GB 2760-2011 was used as sulfites content in food, the intake of sulfites in most surveyed populations was lower than the acceptable daily intake (ADI). Excess intake of sulfites was found in all the surveyed groups when a high percentile of sulfites in food was in taken. Moreover, children aged 1-6 years are at a high risk to intake excess sulfites. The primary cause for the excess intake of sulfites in Chinese people is the overuse and abuse of sulfites by the food industry. The current MPL of sulfites in GB 2760-2011 protects the health of most populations.

Role of MicroRNAs in Dietary Interventions for Obesity and Obesity-Related Diseases.

Obesity and related metabolic syndromes pose a serious threat to human health and quality of life. A proper diet is a safe and effective strategy to prevent and control obesity, thus maintaining overall health. However, no consensus exists on the connotations of proper diet, and it is attributed to various factors, including "nutritional dark matter" and the "matrix effect" of food. Accumulating evidence confirms that obesity is associated with the in vivo levels of miRNAs, which serve as potential markers and regulatory targets for obesity onset and progression; food-derived miRNAs can regulate host obesity by targeting the related genes or gut microbiota across the animal kingdom. Host miRNAs mediate food nutrient-gut microbiota-obesity interactions. Thus, miRNAs are important correlates of diet and obesity onset. This review outlines the recent findings on miRNA-mediated food interventions for obesity, thereby elucidating their potential applications. Overall, we provide new perspectives and views on the evaluation of dietary nutrition, which may bear important implications for dietary control and obesity prevention.

Subchronic Oral Toxicity Evaluation of Sodium Dehydroacetate: A 90-day Repeated Dose Study in Rats.

Objective: The present study was undertaken to evaluate the subchronic oral toxicity of sodium dehydroacetate (DHA-Na) and to determine the point of departure (POD), which is a critical factor in the establishment of an acceptable dietary intake. Methods: DHA-Na was administered once daily by gavage to Sprague-Dawley rats at dose levels of 0.0, 31.0, 62.0, and 124.0 mg/kg BW per day for 90 days, followed by a recovery period of 4 weeks in the control and 124.0 mg/kg BW per day groups. The outcome parameters were mortality, clinical observations, body weights, food consumption, hematology and clinical biochemistry, endocrine hormone levels, and ophthalmic, urinary, and histopathologic indicators. The benchmark dose (BMD) approach was applied to estimate the POD. Results: Significant decreases were found in the 62.0 and 124.0 mg/kg BW groups in terms of the body weight and food utilization rate, whereas a significant increase was found in the thyroid stimulating hormone levels of the 124.0 mg/kg BW group. Importantly, the 95% lower confidence limit on the BMD of 51.7 mg/kg BW was modeled for a reduction in body weight. Conclusion: The repeated-dose study indicated the slight systemic toxicity of DHA-Na at certain levels (62.0 and 124.0 mg/kg BW) after a 90-day oral exposure.

In Vitro Metabolism by Aldehyde Oxidase Leads to Poor Pharmacokinetic Profile in Rats for c-Met Inhibitor MET401.

BACKGROUND AND OBJECTIVES: MET401 is a potent and selective c-Met inhibitor with a novel triazolopyrimidine scaffold. The aim of this study was to determine the pharmacokinetic profile of MET401 in preclinical species, and to identify the metabolic soft spot and enzyme involved, in order to help medicinal chemists to modify the compound to improve the pharmacokinetic profile. METHODS: A metabolite identification study was performed in different liver fractions from various species. Chemical inhibition with selective cytochrome P450 (CYP) and molybdenum hydroxylase inhibitors was carried out to identify the enzyme involved. The deuterium substitution strategy was adopted to reduce metabolism. Pharmacokinetic studies were performed in rats to confirm the effect. RESULTS: Although M-2 is a minor metabolite in liver microsomal incubations, it became the predominant metabolite in incubations with liver S9, cytosol, hepatocytes and rat pharmacokinetic study. M-2 was synthesized enzymatically and the structure was identified as a mono-oxidation on the triazolopyrimidine moiety. The M-2 formation was ascribed to aldehyde oxidase (AO)-mediated metabolism based on the following evidence-M-2 production was NADPH independent, pan-CYP inhibitor 1-aminobenzotriazole and xanthine oxidase inhibitor allopurinol did not inhibit M-2 formation, and AO inhibitors menadione and raloxifene inhibited M-2 formation. The deuterated analog MET763 demonstrated an improved pharmacokinetic profile with lower clearance, longer terminal half-life and double oral exposure compared with MET401 in rats. CONCLUSIONS: These results indicate that the main metabolic pathway of MET401 is AO-mediated metabolism, which leads to poor in vivo pharmacokinetic profiles in rodents. The deuterium substitution strategy could be used to reduce AO-mediated metabolism liability.