Yong Chu

Rational design of 2-pyrrolinones as inhibitors of HIV-1 integrase

HIV-1 integrase is an essential enzyme for viral replication and a validated target for the development of drugs against AIDS. With an aim to discover new potent inhibitors of HIV-1 integrase, we developed a pharmacophore model based on reported inhibitors embodying structural diversity. Eight compounds of 2-pyrrolinones fitting all the features of the pharmacophore query were found through the screening of an in-house database. These candidates were successfully synthesized, and three of them showed strand transfer inhibitory activity, in which, one compound showed antiviral activity. Further mapping analysis and docking studies affirmed these results.

Design, synthesis and biological evaluation of benzothiazepinones (BTZs) as novel non-ATP competitive inhibitors of glycogen synthase kinase-3β (GSK-3β)

Glycogen synthase kinase-3β (GSK-3β) plays a key role in type II diabetes and Alzheimers diseases, to which non-ATP competitive inhibitors represent an effectively therapeutical approach due to their good specificity. Herein, a series of small molecules benzothiazepinones (BTZs) as novel non-ATP competitive inhibitors of GSK-3β have been designed and synthesized. The in vitro evaluation performed by luminescent assay showed most BTZ derivatives have inhibitory effects in micromolar scale. Among them compounds 6l, 6t and 6v have the IC50 values of 25.0 μM, 27.8 μM and 23.0 μM, respectively. Moreover 6v is devoid of any inhibitory activity in the assays to other thirteen protein kinases. Besides, SAR is analyzed and a hypothetical enzymatic binding mode is proposed by molecular docking study, which would be useful for new candidates design.

Identification of novel scaffold of benzothiazepinones as non-ATP competitive glycogen synthase kinase-3β inhibitors through virtual screening.

Glycogen synthase kinase-3β (GSK-3β) is an important serine/threonine kinase that has been proved as a key target for neurodegenerative diseases and diabetes. Up to date, most of known inhibitors are bound to the ATP-binding pocket of GSK-3β, which might lead widespread effects due to the high homology between kinases. Recently, some of its non-ATP competitive inhibitors had been confirmed having therapeutical effects owing to their high selectivity. This finding opens a new pathway to study hopeful drugs for treatment of these diseases. However, it is still a challenge nowadays on how to efficiently find non-ATP competitors. Here, we successfully discovered a novel scaffold of benzothiazepinones (BTZs) as selective non-ATP competitive GSK-3β inhibitors through virtual screening approach. A 3D receptor model of substrate binding site of GSK-3β was constructed and applied to screen against drug-like Maybridge database through Autodock program. BTZ compounds were top ranked as efficient hits and were then synthesized for further screening. Among them, the representative compound 4j showed activity to GSK-3β (IC(50): 25 μM) in non-ATP competitive mechanism, and nearly no inhibitory effect on other 10 related protein kinases. Overall, the results point out that BTZ compounds might be useful in treatment of Alzheimers disease and diabetes mellitus as novel GSK-3β inhibitors. It also suggests, on the other hand, that virtual screening would provide a valuable tool in combination with in vitro assays for the identification of novel selective and potent inhibitors.

Discovery, synthesis and biological evaluation of 2-(4-(N-phenethylsulfamoyl)phenoxy)acetamides (SAPAs) as novel sphingomyelin synthase 1 inhibitors

Sphingomyelin synthase (SMS) has been proved to be a potential drug target for the treatment of atherosclerosis. However, few SMS inhibitors have been reported. In this paper, structure-based virtual screening was performed on hSMS1. SAPA 1a was discovered as a novel SMS1 inhibitor with an IC50 value of 5.2 μM in enzymatic assay. A series of 2-(4-(N-phenethylsulfamoyl)phenoxy)acetamides (SAPAs) were synthesized and their biological activities toward SMS1 were evaluated. Among them, SAPA 1j was found to be the most potent SMS1 inhibitor with an IC50 value of 2.1 μM in in vitro assay. The molecular docking studies suggested the interaction modes of SMS1 inhibitors and PC with the active site of SMS1. Site-directed mutagenesis validated the involvement of residues Arg342 and Tyr338 in enzymatic sphingomyelin production. The discovery of SAPA derivatives as a novel class of SMS1 inhibitors would advance the development of more effective SMS1 inhibitors.

Novel benzothiazinones (BTOs) as allosteric modulator or substrate competitive inhibitor of glycogen synthase kinase 3β (GSK-3β) with cellular activity of promoting glucose uptake.

Glycogen synthase kinase 3β (GSK-3β) plays a key role in insulin metabolizing pathway and therefore inhibition of the enzyme might provide an important therapeutic approach for treatment of insulin resistance and type 2 diabetes. Recently, discovery of ATP noncompetitive inhibitors is gaining importance not only due to their generally increased selectivity but also for the potentially subtle modulation of the target. These kinds of compounds include allosteric modulators and substrate competitive inhibitors. Here we reported two benzothiazinone compounds (BTO), named BTO-5h (IC50=8 μM) and BTO-5s (IC50=10 μM) as novel allosteric modulator and substrate competitive inhibitor of GSK-3β, respectively. Their different action modes were proved by kinetic experiments. Furthermore, BTO-5s was selected to check the kinases profile and showed little or even no activity to a panel of ten protein kinases at 100 μM, indicating it has good selectivity. Docking studies were performed to give suggesting binding modes which can well explain their impacts on the enzyme. Moreover, cell experiments displayed both compounds reduced the phosphorylation level of glycogen synthase in an intact cell, and greatly enhanced the glucose uptake in both HpG2 and 3T3-L1 cells. All of these results suggested BTO-5s and BTO-5h maybe have potentially therapeutic value for anti-diabetes. The results also offer a new scaffold for designing and developing selective inhibitors with novel mechanisms of action.

2-(Furan-2-yl)-5-(2-nitro-benz-yl)-2,3-dihydro-1,5-benzothia-zepin-4(5H)-one.

The title compound, C(20)H(16)N(2)O(4)S, was prepared by introduction of a 2-nitro-benzyl group to 2-(furan-2-yl)-2,3-dihydro-1,5-benzothia-zepin-4(5H)-one via an alkaline-catalysed reaction. The thia-zepine ring adopts a twist-boat conformation. The furan ring is oriented at dihedral angles of 56.75 (14) and 10.82 (14)° with respect to the two benzene rings, while the two benzene rings make a dihedral angle of 62.96 (10)°. Weak inter-molecular C-H⋯O hydrogen bonds occur in the crystal structure.

Discovery of 4-Benzyloxybenzo[d]isoxazole-3-amine Derivatives as Highly Selective and Orally Efficacious Human Sphingomyelin Synthase 2 Inhibitors that Reduce Chronic Inflammation in db/db Mice

Sphingomyelin synthase 2 (SMS2) is a promising therapeutic target for several chronic inflammation-associated diseases, including atherosclerosis, fatty liver, and insulin resistance. Herein, we report the identification of 4-benzyloxybenzo[ d]isoxazole-3-amine derivatives as potent and highly selective SMS2 inhibitors through a conformational restriction strategy. After systematic structural modifications, several compounds with high selectivity and good potency in vitro were selected for further evaluation. Compound 15w demonstrated good pharmacokinetics (oral bioavailability, F = 56%) in vivo and has an inhibitory potency against sphingomyelin synthase activity when Institute of Cancer Research mice are provided with an oral dose of this compound. In addition, compound 15w attenuated chronic inflammation significantly in db/ db mice after oral dosing for 6 weeks.

Discovery and anti-inflammatory evaluation of benzothiazepinones (BTZs) as novel non-ATP competitive inhibitors of glycogen synthase kinase-3β (GSK-3β)

Glycogen synthase kinase-3β (GSK-3β) has been identified to promote inflammation and its inhibitors have also been proven to treat some inflammatory mediated diseases in animal models. Non-ATP competitive inhibitors inherently have better therapeutical value due to their higher specificity than ATP competitive ones. In this paper, we designed and synthesized a series of new BTZ derivatives as non-ATP competitive GSK-3β inhibitors. Kinetic analysis revealed two typical compounds 6j and 3j showed the different non-ATP competitive mechanism of substrate competition or allosteric modulation to GSK-3β, respectively. As expected, the two compounds showed good specificity in a panel test of 16 protein kinases, even to the closest enzymes, like CDK-1/cyclin B and CK-II. The in vivo results proved that both compounds can greatly attenuate the LPS-induced acute lung injury (ALI) and diminish inflammation response in mice by inhibiting the mRNA expression of IL-1β and IL-6. Western blot analysis demonstrated that they negatively regulated GSK-3β, and the mechanism of the observed beneficial effects of the inhibitors may involve both the increased phosphorylation of the Ser9 residue on GSK-3β and protein expression of Sirtuin 1 (SIRT1). The results support that such novel BTZ compounds have a protective role in LPS-induced ALI, and might be attractive candidates for further development of inflammation pharmacotherapy, which greatly thanks to their inherently high selectivities by the non-ATP competitive mode of action. Finally, we proposed suggesting binding modes by Docking study to well explain the impacts of compounds on the target site.