Seung Kyu Kang

Synthesis and PTP1B inhibition of 1,2-naphthoquinone derivatives as potent anti-diabetic agents.

A new series of 1,2-naphthoquinone derivatives was synthesized by various synthetic methods and evaluated for their ability to inhibit protein tyrosine phosphatase 1B (PTP1B). 1,2-Naphthoquinone derivatives with substituent at R(4) position showed submicromolar inhibitory activity, and compound 24 demonstrated 10- to 60-fold selectivity against the tested phosphatases. Also, several 4-aryl-1,2-naphthoquinone derivatives with substituents at R(3), R(6), R(7), or/and R(8) showed submicromolar inhibitory activity and good plasma stability.

Synthesis of 1,2,3-trisubstituted pyrrolo[3,2-c]quinolines via palladium-catalyzed heteroannulation with internal alkynes

Abstract Various 1,2,3-trisubstituted pyrrolo[3,2- c ]quinolines were synthesized by palladium-catalyzed heteroannulation of 4-amino-3-iodoquinoline derivatives and internal alkynes. The 1,2,3-trisubstituted pyrrolo[3,2- c ]quinolines could be further transformed by desilylation, debenzylation, or substitution.

Anti-diabetic and anti-adipogenic effects of a novel selective 11β-hydroxysteroid dehydrogenase type 1 inhibitor, 2-(3-benzoyl)-4-hydroxy-1,1-dioxo-2H-1,2-benzothiazine-2-yl-1-phenylethanone (KR-66344)

The selective inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) have considerable potential for treating type 2 diabetes mellitus and metabolic syndrome. In the present study, we investigated the anti-diabetic and anti-adipogenic effects of 2-(3-benzoyl)-4-hydroxy-1,1-dioxo-2H-1,2-benzothiazine-2-yl-1-phenylethanone (KR-66344), as a 11β-HSD1 inhibitor; we also investigated the underlying molecular mechanisms in the cortisone-induced 3T3-L1 adipogenesis model system and C57BL/6-Lep(ob/ob) mice. KR-66344 concentration-dependently inhibited 11β-HSD1 activity in human liver microsome, mouse C2C12 myotube and human SW982 cells. In the C57BL/6-Lep(ob/ob) mice study, the administration of KR-66344 (200mg/kg/d, orally for 5 days) improved the glucose intolerance as determined by the oral glucose tolerance test, in which the area under the curve (AUC) of the plasma glucose concentration was significantly reduced by 27% compared with the vehicle treated group. Further, KR-66344 suppressed adipocyte differentiation on cortisone-induced adipogenesis in 3T3-L1 cells is associated with the suppression of the cortisone-induced mRNA levels of FABP4, G3PD, PPARγ2 and Glut4, and 11β-HSD1 expression and activity. Our results additionally demonstrate evidence showing that KR-66344 improved glycemic control and inhibited adipogenesis via 11β-HSD1 enzyme activity. Taken together, these results may provide evidence of the therapeutic potential of KR-66344, as a 11β-HSD1 inhibitor, in obesity and type 2 diabetes patients with metabolic syndrome.

Discovery of cyclicsulfonamide derivatives as 11β-hydroxysteroid dehydrogenase 1 inhibitors

A new series of cyclic sulfonamide derivatives was synthesized and evaluated for their ability to inhibit 11beta-HSD1. Cyclic sulfonamides with phenylacetyl substituents at the 2-position showed nanomolar inhibitory activities. Among them, compound 4e exhibited a good in vitro inhibitory activity and selectivity toward human 11beta-HSD2.

Synthesis and biological evaluation of homopiperazine derivatives with beta-aminoacyl group as dipeptidyl peptidase IV inhibitors

Compounds with homopiperazine skeleton are designed to find a potent DPP-IV inhibitor without inhibiting CYP. Thus a series of beta-aminoacyl-containing homopiperazine derivatives was synthesized and evaluated. Compounds with acid moiety were found to be potent inhibitors of DPP-IV without inhibiting CYP 3A4. More specifically, compound 7m showed nanomolar activity with no inhibition towards five subtypes of CYPs, was considered as a prototype for further derivatization. Based on its X-ray co-crystal structure with human DPP-IV, we identified compounds 7s and 7t which showed good in vitro activity, no CYP inhibition, and good selectivity.

Synthesis and biological evaluation of pyrazoline analogues with β-amino acyl group as dipeptidyl peptidase IV inhibitors

A series of pyrazoline derivatives with beta-amino acyl group were synthesized and evaluated for their ability to inhibit dipeptidyl peptidase IV. Several pyrazoline derivatives exhibited submicromolar inhibitory activities against DPP-IV. X-ray co-crystal structure of initial hit compound 1h was determined. Among this series, carboxylic acid substituted pyrazoline derivative 2u was the most active and greatly decreased the inhibitory activity toward CYP3A4 enzyme.

Synthesis and biological evaluation of cyclic sulfamide derivatives as 11β-hydroxysteroid dehydrogenase 1 inhibitors.

A new series of cyclic sulfamide derivatives were synthesized and evaluated for their ability to inhibit 11β-HSD1. Among this series, 18e showed good in vitro activity toward human 11β-HSD1, selectivity against 11β-HSD2, microsomal stability, and pharmacokinetic and safety profiles (hERG, CYP, and acute toxicity). Additionally, 18e exhibited good in vivo efficacy in rat and monkey models.

Discovery of a New and Efficient Small Molecule for Neuronal Differentiation from Mesenchymal Stem Cell

A new synthetic small molecule, compound 1, which induced a neuronal differentiation from mesenchymal stem cells (MSCs) with an excellent efficiency, was identified. Furthermore the differentiated cell by 1 showed the neural electrophysiological and cholinergic neuron properties.

A novel 11β-HSD1 inhibitor improves diabesity and osteoblast differentiation

Selective inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) have considerable potential as treatment for osteoporosis as well as metabolic syndrome including type 2 diabetes mellitus. Here, we investigated the anti-diabetic, anti-adipogenic, and anti-osteoporotic activity of KR-67500, as a novel selective 11β-HSD1 inhibitor. Cellular 11β-HSD1 activity was tested based on a homogeneous time-resolved fluorescence method. Oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) levels were measured in diet-induced obese (DIO)-C57BL/6 mice administered KR-67500 (50  mg/kg per day, p.o.) for 28 days and, additionally, its anti-diabetic effect was evaluated by OGTT and ITT. The in vitro anti-adipogenic effect of KR-67500 was determined by Oil Red O Staining. The in vitro anti-osteoporotic activity of KR-67500 was evaluated using bone morphogenetic protein 2 (BMP2)-induced osteoblast differentiation and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation model systems. KR-67500 improved the in vivo glucose tolerance and insulin sensitivity in DIO-C57BL/6 mice. KR-67500 suppressed cortisone-induced differentiation of 3T3-L1 cells into adipocytes. KR-67500 enhanced BMP2-induced osteoblastogenesis in C2C12 cells and inhibited RANKL-induced osteoclastogenesis in mouse bone marrow-derived macrophages. KR-67500, a new selective 11β-HSD1 inhibitor, may provide a new therapeutic window in the prevention and/or treatment of type 2 diabetes, obesity, and/or osteoporosis.

Anti-diabetic and anti-adipogenic effects of a novel selective 11β-hydroxysteroid dehydrogenase type 1 inhibitor in the diet-induced obese mice

Glucocorticoid excess (Cushings syndrome) causes metabolic syndrome such as visceral obesity, insulin resistance, diabetes mellitus, dyslipidaemia and hypertension. The selective inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) have considerable potential for treating type 2 diabetes mellitus and metabolic syndrome. In the present study, we investigated the anti-diabetic and anti-adipogenic effects of 4-(2-(1,1-dioxido-6-(2,4,6-trichlorophenyl)-1,2,6-thiadiazinan-2-yl)acetamido)adamantane-1-carboxamide (KR-67183), a novel selective 11β-HSD1 inhibitor; we also investigated the underlying molecular mechanisms in the cortisone-induced 3T3-L1 adipogenesis model system and diet-induced obese (DIO) mice. KR-67183 concentration-dependently inhibited 11β-HSD1 activity in human and mouse 11β-HSD1 over-expressed cells and in the ex vivo assay of C57BL/6 mice. In the study with DIO mice, the administration of KR-67183 (20 and 50mg/kg/day, orally for 28 days) improved the glucose tolerance and insulin sensitivity with suppressed 11β-HSD1 activity in the liver and fat. However, KR-67183 showed no change in the adrenal gland weight/body weight ratio and plasma corticosterone concentration in DIO mice. Further, KR-67183 suppressed adipocyte differentiation on cortisone-induced adipogenesis in 3T3-L1 cells is associated with the suppression of the cortisone-induced mRNA levels of FABP4, PPARγ2 and GLUT4, and 11β-HSD1 activity. Taken together, it is suggested that a selective 11β-HSD1 inhibitor, KR-67183, may provide a new therapeutic window in the prevention and treatment without toxicity in type 2 diabetes with obesity.