A Novel Diphenylthiosemicarbazide Is a Potential Insulin Secretagogue for Anti-Diabetic Agen.

Insulin secretagogues are used for treatment of type 2 diabetes. We attempted to discover novel small molecules to stimulate insulin secretion by using in silico similarity search using sulfonylureas as query, followed by measurement of insulin secretion. Among 38 compounds selected by in silico similarity search, we found three diphenylsemicarbazides and one quinolone that stimulate insulin secretion. We focused on compound 8 (C8), which had the strongest insulin-secreting effect. Based on the structure-activity relationship of C8-derivatives, we identified diphenylthiosemicarbazide (DSC) 108 as the most potent secretagogue. DSC108 increased the intracellular Ca2+ level in MIN6-K8 cells. Competitive inhibition experiment and electrophysiological analysis revealed sulfonylurea receptor 1 (SUR1) to be the target of DSC108 and that this diphenylthiosemicarbazide directly inhibits ATP-sensitive K+ (KATP) channels. Pharmacokinetic analysis showed that DSC108 has a short half-life in vivo. Oral administration of DSC108 significantly suppressed the rises in blood glucose levels after glucose load in wild-type mice and improved glucose tolerance in the Goto-Kakizaki (GK) rat, a model of type 2 diabetes with impaired insulin secretion. Our data indicate that DSC108 is a novel insulin secretagogue, and is a lead compound for development of a new anti-diabetic agent.

Preclinical pharmacokinetics, tissue distribution and excretion studies of a novel anti-candidal agent-thiosemicarbazide derivative of isoniazid (TSC-INH) by validated UPLC-MS/MS assay.

A simple and sensitive UPLC-MS/MS assay was developed and validated for rapid determination of thiosemicarbazide derivative of isoniazid (TSC-INH), a potent anti-candidal agent in rat plasma, tissues, urine and feces. All biological samples were prepared by protein precipitation method using celecoxib as an internal standard (IS). Chromatographic separation was achieved on Acquity BEH™ C18 (50×2.1 mm, 1.7 µm) column using gradient mobile phase of acetonitrile and water (containing 0.1% formic acid) at flow rate of 0.3 mL/min. The MRM transitions were monitored at m/z 305.00→135.89 for TSC-INH and m/z 380.08→316.03 for IS in ESI negative mode. All validation parameter results were within the acceptable range described in guideline for bioanalytical method validation. The pharmacokinetic study showed that the compound TSC-INH was orally active with 66% absolute bioavailability in rats. It was rapidly absorbed with peak plasma concentration of 1985.92 ng/mL achieved within 1 h after single oral dose (10 mg/kg) administration. TSC-INH exhibited rapid distribution across the body with highest levels in liver and lungs. Penetration in brain tissues suggests that TSC-INH crossed the blood brain barrier. Only 5.23% of the orally administered drug was excreted as unconverted form in urine and feces implying that TSC-INH was metabolized extensively before excretion. With the preliminary knowledge of in vivo pharmacokinetics and disposition properties, this study will be beneficial for further development of compound TSC-INH in future studies.

A rapid and sensitive LC-MS/MS method for evaluation of the absolute oral bioavailability of a novel c-Met tyrosine kinase inhibitor QBH-196 in rats.

A sensitive, selective and high-throughput UPLC-MS/MS method was developed and validated for the determination of a novel c-Met tyrosine kinase inhibitor, QBH-196, in rat plasma. QBH-196 and its analog BH357 (IS) were extracted from rat plasma using a mixture of dichloromethane and N-hexane (2:3, v/v). The chromatographic separation was carried out on Phenomenex C18 column (50 × 2.1 mm, 2.6 µm particle size) with a gradient mobile phase of methanol (A) and water containing 0.05% formic acid (B) at a flow rate of 0.2 mL/min. The assay was performed by positive electrospray ionization in multiple reaction monitoring mode using transitions of m/z 622.68 → 140.41 for QBH-196 and m/z 591.19 →126.21 for the IS, respectively. Good linearity was obtained over the concentration range of 8.0-4000 ng/mL (r(2) > 0.99) for QBH-196 and the lower limit of quantification was 8.0 ng/mL in rat plasma. Validations of the method, including its sensitivity, extraction recovery, matrix effect, intra- and inter-day precision, accuracy and stability, were all within acceptable limits. The established method was successfully applied to determine absolute oral bioavailability of QBH-196 in rats for the first time. The mean oral absolute bioavailability of QBH-196 was found to be about 40.8% and the elimination half-life was 40.0 ± 13.1 h. This result suggested that QBH-196 exhibits good oral absorption in vivo, which is very important for the further development of QBH-196 as a new oral anticancer drug.

Partial characterization of the 1-anilino-8-naphthalene sulfonate-adrenochrome semicarbazide interaction site in erythrocyte ghost membrane fragments.

The effect of adrenochrome semicarbazide on the conformation of erythrocyte ghost membranes has been studied by ANS fluorescence, lipid and sulfhydryl spin labels and circular dichroism. No large conformational alterations in the membrane were detected by these techniques. Noncompetitive quenching of ANS fluorescence by ADCS suggests ADCS to interact with the membrane at sites close to the ANS binding domain.