DNA gyrase and topoisomerase IV are well-validated pharmacological targets, and quinolone antibacterial drugs are marketed as their representative inhibitors. However, in recent years, resistance to these existing drugs has become a problem, and new chemical classes of antibiotics that can combat resistant strains of bacteria are strongly needed. In this study, we applied our hit-to-lead (H2L) chemistry for the identification of a new chemical class of GyrB/ParE inhibitors by efficient use of thermodynamic parameters. Investigation of the core fragments obtained by fragmentation of high-throughput screening hit compounds and subsequent expansion of the hit fragment was performed using isothermal titration calorimetry (ITC). The 8-(methylamino)-2-oxo-1,2-dihydroquinoline derivative 13e showed potent activity against Escherichia coli DNA gyrase with an IC50 value of 0.0017 μM. In this study, we demonstrated the use of ITC for primary fragment screening, followed by structural optimization to obtain lead compounds, which advanced into further optimization for creating novel antibacterial agents.

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We previously reported 2-[2-(4-tert-butylphenyl)ethyl]-N-(4-fluorophenyl)-1,2,3,4-tetrahydroisoquinoline-6-sulfonamide 2 as on orally available monoacylglycerol acyltransferase 2 (MGAT2) inhibitor which exhibited an in vivo efficacy at an oral dose of 100 mg/kg in a mouse oral lipid tolerance test. Further optimization of compound 2 to improve the intrinsic potency culminated in the identification of compound 11. Compound 11 showed a >50-fold lower IC 50 against human MGAT2 enzyme than 2. Oral administration of 11 at a dose of 3 mg/kg in the oral lipid tolerance test resulted in significant suppression of triglyceride synthesis.Key words monoacylglycerol acyltransferase 2; fat absorption; oral lipid tolerance test; tetrahydroisoquinoline A rapid increases of obesity, type 2 diabetes and cardiovascular disease have become a huge issue in the world's industrialized countries. The unmet medical need for the treatment of these diseases has promoted the identification of many new targets, one of which is the inhibition of triacylglycerol synthesis.Dietary-derived fats are degraded in the gastrointestinal tract and then taken up by small-intestinal epithelial cells. Acyl CoA : monoacylglycerol acyltransferase (MGAT), which catalyzes the synthesis of diacylglycerol from monoacylglycerol and acyl-CoA, plays a crucial role in triglyceride (TG) re-synthesis in the small intestine. 1) After re-synthesis into neutral fats in the cells, 2) the neutral fats are packaged into chylomicrons, secreted into the lymphatics, and taken up into body. Therefore, the inhibition of activity of this enzyme is expected to suppress re-synthesis of TG and lead to reduce fat absorption.Three isoforms of MGAT enzyme have been identified, [3][4][5] and MGAT2 is highly expressed in small intestine in both humans and mice.1) The phenotype of MGAT2 deficient mice has been already reported.6) These mice were viable and fertile without apparent abnormalities. After these mice were orally given dietary oil (oral lipid tolerance test), plasma TG levels of these mice were significantly lower than those of the wild type. In addition, MGAT2 knock-out mice showed resistance to obesity, glucose intolerance, and hypercholesterolemia induced by a high fat diet. Furthermore, these mice demonstrated increased oxygen consumption without high-fat feeding, and MGAT2 was expected to modulate energy expenditure. 7,8) These results implied that inhibition of MGAT2 could be an attractive mechanism for reduction of fat absorption and treatment of obesity and associated metabolic disorders.Some small molecule MGAT2 inhibitors have been disclosed. [9][10][11][12][13][14][15] As shown in Fig. 1, AstraZeneca's compound 1 reported in the literature showed potent MGAT2 inhibitory activity and a significant reduction of plasma TG concentration after an oral administration at a dose of 150 mg/kg in mice oral lipid tolerance test. [16][17][18] We have also reported an orally available MGAT2 inhibitor, 19) 2-[2-(4-tert-butylphenyl)-ethyl]-N-(4-fluorophenyl)-1,2,3,4-tetrahydrois...

Gonorrhea is a common, sexually transmitted disease caused by Neisseria gonorrhoeae. Multidrug-resistant N. gonorrhoeae is an urgent threat, and the development of a new antimicrobial agent that functions via a new mechanism is strongly desired. We evaluated the in vitro and in vivo activities of a DNA gyrase/topoisomerase IV inhibitor, TP0480066, which is a novel 8-(methylamino)-2-oxo-1,2-dihydroquinoline derivative. The MICs of TP0480066 were substantially lower than those of other currently or previously used antimicrobials against gonococcal strains demonstrating resistance to fluoroquinolones, macrolides, β-lactams and aminoglycosides (MICs, ≤0.0005 μg/mL). Additionally, no cross-resistance was observed between TP0480066 and ciprofloxacin. The frequencies of spontaneous resistance to TP0480066 for N. gonorrhoeae ATCC 49226 were below the detection limit (<2.4 × 10−10) at concentrations equivalent to 32 × MIC. TP0480066 also showed potent in vitro bactericidal activity and in vivo efficacy in a mouse model of N. gonorrhoeae infection. These data suggest that TP0480066 is a candidate antimicrobial agent for gonococcal infections.