Demonstration of the Innate Electrophilicity of 4-(3-(Benzyloxy)phenyl)-2-(Ethylsulfinyl)-6-(Trifluoromethyl)pyrimidine (BETP), a Small Molecule Positive Allosteric Modulator of the Glucagon-Like Peptide-1 (GLP-1) Receptor.

Demonstration of the Innate Electrophilicity of 4-(3-(Benzyloxy)phenyl)-2-(ethylsulfinyl)-6-(trifluoromethyl)pyrimidine (BETP), a Small Molecule Positive Allosteric Modulator of the Glucagon-Like Peptide-1 (GLP-1) Receptor.

Drug Metab Dispos. 2013 May 7;
Eng H, Sharma R, McDonald TS, Edmonds DJ, Fortin JP, Li X, Stevens BD, Griffith DA, Limberakis C, Nolte WM, Price DA, Jackson M, Kalgutkar AS

4-(3-(Benzyloxy)phenyl)-2-(ethylsulfinyl)-6-(trifluoromethyl)pyrimidine (BETP) represents a novel small molecule activator of the glucagon-like peptide-1 receptor (GLP-1R), and exhibits glucose-dependent insulin secretion in rats following intravenous (but not oral) administration. In order to explore the quantitative pharmacology associated with GLP-1R agonism in preclinical species, the in vivo pharmacokinetics of BETP were examined in rats after intravenous and oral dosing. Failure to detect BETP in circulation after oral administration of a 10 mg/kg dose in rats was consistent with the lack of an insulinotropic effect of orally administered BETP in this species. Likewise, systemic concentrations of BETP in the rat upon intravenous administration (1 mg/kg) were minimal (and sporadic). In vitro incubations in bovine serum albumin, plasma and liver microsomes from rodents and human indicated a facile degradation of BETP. Failure to detect metabolites in plasma and liver microsomal incubations in the absence of nicotinamide adenine dinucleotide phosphate was suggestive of a covalent interaction between BETP and a protein amino acid residue(s) in these matrices. Incubations of BETP with glutathione (GSH) in buffer revealed a rapid nucleophilic displacement of the ethylsulfoxide functionality by GSH to yield adduct M1, which indicated that BETP was intrinsically electrophilic. The structure of M1 was unambiguously identified by comparison of its chromatographic and mass spectral properties with an authentic standard. The GSH conjugate of BETP was also characterized in NADPH- and GSH-supplemented liver microsomes, and in plasma samples from the pharmacokinetic studies. Unlike BETP, M1 was inactive as an allosteric modulator of the GLP-1R. HubMed – drug


Metformin, at Concentrations Corresponding to the Treatment of Diabetes, Potentiates the Cytotoxic Effects of Carboplatin in Cultures of Ovarian Cancer Cells.

Reprod Sci. 2013 May 7;
Erices R, Bravo ML, Gonzalez P, Oliva B, Racordon D, Garrido M, Ibañez C, Kato S, Brañes J, Pizarro J, Barriga MI, Barra A, Bravo E, Alonso C, Bustamente E, Cuello MA, Owen GI

The use of the type 2 diabetics drug metformin has been correlated with enhanced progression-free survival in ovarian cancer. The literature has speculated that this enhancement is due to the high concentration of metformin directly causing cancer cell death. However, this explanation does not fit with clinical data reporting that the women exposed to constant micromolar concentrations of metformin, as present in the treatment of diabetes, respond better to chemotherapy. Herein, our aim was to examine whether micromolar concentrations of metformin alone could bring about cancer cell death and whether micromolar metformin could increase the cytotoxic effect of commonly used chemotherapies in A2780 and SKOV3 cell lines and primary cultured cancer cells isolated from the peritoneal fluid of patients with advanced ovarian cancer. Our results in cell lines demonstrate that no significant loss of viability or change in cell cycle was observed with micromolar metformin alone; however, we observed cytotoxicity with micromolar metformin in combination with chemotherapy at concentrations where the chemotherapy alone produced no loss in viability. We demonstrate that previous exposure and maintenance of metformin in conjunction with carboplatin produces a synergistic enhancement in cytotoxicity of A2780 and SKOV3 cells (55% and 43%, respectively). Furthermore, in 5 (44%) of the 11 ovarian cancer primary cultures, micromolar metformin improved the cytotoxic response to carboplatin but not paclitaxel or doxorubicin. In conclusion, we present data that support the need for a clinical study to evaluate the adjuvant maintenance or prescription of currently approved doses of metformin during the chemotherapeutic treatment of ovarian cancer. HubMed – drug


An updated review on drug-induced cholestasis: Mechanisms and investigation of physicochemical properties and pharmacokinetic parameters.

J Pharm Sci. 2013 May 7;
Yang K, Köck K, Sedykh A, Tropsha A, Brouwer KL

Drug-induced cholestasis is an important form of acquired liver disease and is associated with significant morbidity and mortality. Bile acids are key signaling molecules, but they can exert toxic responses when they accumulate in hepatocytes. This review focuses on the physiological mechanisms of drug-induced cholestasis associated with altered bile acid homeostasis due to direct (e.g., bile acid transporter inhibition) or indirect (e.g., activation of nuclear receptors, altered function/expression of bile acid transporters) processes. Mechanistic information about the effects of a drug on bile acid homeostasis is important when evaluating the cholestatic potential of a compound, but experimental data often are not available. The relationship between physicochemical properties, pharmacokinetic parameters, and inhibition of the bile salt export pump among 77 cholestatic drugs with different pathophysiological mechanisms of cholestasis (i.e., impaired formation of bile vs. physical obstruction of bile flow) was investigated. The utility of in silico models to obtain mechanistic information about the impact of compounds on bile acid homeostasis to aid in predicting the cholestatic potential of drugs is highlighted. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci. HubMed – drug


In silico screening on the 3D-model of the Plasmodium vivax SUB1 protease leads to the validation of a novel anti-parasite compound.

J Biol Chem. 2013 May 7;
Bouillon A, Giganti D, Benedet C, Gorgette O, Pêtres S, Crublet E, Girard-Blanc C, Witkowski B, Ménard D, Nilges M, Mercereau-Puijalon O, Stoven V, Barale JC

Widespread drug resistance calls for the urgent development of new antimalarials that target novel steps in the life cycle of P.falciparum and P.vivax. The essential subtilisin-like serine-protease SUB1 of Plasmodium merozoites plays a dual role in egress from and invasion into host erythrocytes. It belongs to a new generation of attractive drug targets against which specific potent inhibitors are actively searched. We characterize here the P. vivax SUB1 enzyme and show that it displays a typical auto-processing pattern and apical localization in P. vivax merozoites. To search for small PvSUB1 inhibitors, we took advantage of the similarity of SUB1 with bacterial subtilisins and generated P. vivax SUB1 3D-models. The structure-based virtual screening of a large commercial chemical compounds library identified 306 virtual best hits, of which 37 were experimentally confirmed inhibitors, with 5 with Ki<50?M for PvSUB1. Interestingly, they belong to different chemical families. The most promising competitive inhibitor of PvSUB1 (Cpd2) was equally active on PfSUB1 and displayed anti-P.falciparum and P.berghei activity in vitro and in vivo, respectively. Cpd2 inhibited the endogenous PfSUB1 as illustrated by the inhibited maturation of its natural substrate PfSERA5 and inhibited parasite egress and subsequent erythrocyte invasion. These data indicate that the strategy of in silico screening of 3D-models to select for virtual inhibitors combined with stringent biological validation successfully identified several inhibitors of the PvSUB1 enzyme. The most promising hit proved to be a potent cross-inhibitor of PfSUB1, laying the grounds for the development of a globally active small compound antimalarial. HubMed – drug