Xinyu You

Synthesis and structure–activity relationships evaluation of benzothiazinone derivatives as potential anti-tubercular agents

N-Alkyl and heterocycle substituted 1,3-benzothiazin-4-one (BTZ) derivatives were synthesized. The anti-mycobacterial activities of these compounds were evaluated by determination of minimal inhibitory concentration (MIC) for Mycobacterium tuberculosis H37Ra and M. tuberculosis H37Rv. It was found that an extended or branched alkyl chain analog could enhance the potency, and activities of N-alkyl substituted BTZs were not affected by either nitro or trifluoromethyl at 6-position. Trifluoromethyl plays an important role in maintaining anti-tubercular activity in the piperazine or piperidine analogs. Compound 8o, which contains an azaspirodithiolane group, showed a MIC of 0.0001 μM against M. tuberculosis H37Rv, 20-fold more potent than BTZ043 racemate. These results suggested that the volume and lipophilicity of the substituents were important in maintaining activity. In addition, compound 8o was nontoxic to Vero cells and orally bioavailable in a preliminary pharmacokinetics study.

Discovery of imidazo[2,1-b]thiazole HCV NS4B inhibitors exhibiting synergistic effect with other direct-acting antiviral agents.

The design, synthesis, and SAR studies of novel inhibitors of HCV NS4B based on the imidazo[2,1-b]thiazole scaffold were described. Optimization of potency with respect to genotype 1b resulted in the discovery of two potent leads 26f (EC50 = 16 nM) and 28g (EC50 = 31 nM). The resistance profile studies revealed that 26f and 28g targeted HCV NS4B, more precisely the second amphipathic α helix of NS4B (4BAH2). Cross-resistance between our 4BAH2 inhibitors and other direct-acting antiviral agents targeting NS3/4A, NS5A, and NS5B was not observed. For the first time, the synergism of a series of combinations based on 4BAH2 inhibitors was evaluated. The results demonstrated that our 4BAH2 inhibitor 26f was synergistic with NS3/4A inhibitor simeprevir, NS5A inhibitor daclatasvir, and NS5B inhibitor sofosbuvir, and it could also reduce the dose of these drugs at almost all effect levels. Our study suggested that favorable effects could be achieved by combining 4BAH2 inhibitors such as 26f with these approved drugs and that new all-oral antiviral combinations based on 4BAH2 inhibitors were worth developing to supplement or even replace current treatment regimens for curing HCV infection.

Selective inhibition of EZH2 by ZLD1039 blocks H3K27methylation and leads to potent anti-tumor activity in breast cancer

Enhancer of zeste homolog 2 (EZH2) is a candidate oncogenic driver due to its prevalent overexpression and aberrant repression of tumor suppressor genes in diverse cancers. Therefore, blocking EZH2 enzyme activity may present a valid therapeutic strategy for the treatment of cancers with EZH2 overexpression including breast cancers. Here, we described ZLD1039 a potent, highly selective, and orally bioavailable small molecule inhibitor of EZH2, which inhibited breast tumor growth and metastasis. ZLD1039 considerably inhibited EZH2 methyltransferase activity with nanomolar potency, decreased global histone-3 lysine-27 (H3K27) methylation, and reactivated silenced tumor suppressors connected to increased survival of patients with breast cancer. Comparable to conditional silencing of EZH2, its inhibition by ZLD1039 decreased cell proliferation, cell cycle arrest, and induced apoptosis. Comparably, treatment of xenograft-bearing mice with ZLD1039 led to tumor growth regression and metastasis inhibition. These data confirmed the dependency of breast cancer progression on EZH2 activity and the usefulness of ZLD1039 as a promising treatment for breast cancer.

Synthesis and antitubercular evaluation of 4-carbonyl piperazine substituted 1,3-benzothiazin-4-one derivatives

Tuberculosis (TB) remains a major human health problem. New therapeutic antitubercular agents are urgent needed to control the global tuberculosis pandemic. We synthesized a new series of 4-carbonyl piperazine substituted 1,3-benzothiazin-4-one derivatives and evaluated their anti-mycobacterial activities against Mycobacterium tuberculosis H37Ra as well as their druggabilities. The results showed that most of these derivatives, especially the compounds with simple alkyl side chains, exhibited good antitubercular activities and favorable aqueous solubilities with no obvious cytotoxicity. It suggested that the 4-carbonyl piperazine substituents in benzothiazinone scaffold were well tolerated, in which the compound 8h, with an antitubercular activity of MIC 0.008 μM, exhibited an excellent aqueous solubility of 104 μg/mL, which was 100-fold better than the potent DprE1 inhibitor Comp.1 (BTZ038), also more soluble than PBTZ169.

Discovery and structure–activity relationships study of novel thieno[2,3-b]pyridine analogues as hepatitis C virus inhibitors

Current treatment for hepatitis C is barely satisfactory, there is an urgent need to develop novel agents for combating hepatitis C virus infection. This study discovered a new class of thieno[2,3-b]pyridine derivatives as HCV inhibitors. First, a hit compound characterized by a thienopyridine core was identified in a cell-based screening of our privileged small molecule library. And then, structure activity relationship study of the hit compound led to the discovery of several potent compounds without obvious cytotoxicity in vitro (12c, EC50=3.3μM, SI >30.3, 12b, EC50=3.5μM, SI >28.6, 10l, EC50=3.9μM, SI >25.6, 12o, EC50=4.5μM, SI >22.2, respectively). Although the mechanism of them had not been clearly elucidated, our preliminary optimization of this class of compounds had provided us a start point to develop new anti-HCV agents.

The Preparation and Evaluation of Water-Soluble SKLB610 Nanosuspensions with Improved Bioavailability

The aim of the study was to investigate the potential of nanosuspension to enhance the bioavailability of SKLB610 (Biopharmaceutical Classification System class II drug), a bioactive anticancer compound synthesized in our labs. SKLB610 nanosuspensions were prepared using wet media milling. Physicochemical characteristics of the nanosuspensions were evaluated, including particle size and distribution, dissolution, transmission electron microscopy, atomic force microscopy, thermogravimetric analysis, and X-ray powder diffractometry. The dissolution rate of SKLB610 was greatly improved in nanosuspensions, compared to crude SKLB610. Pharmacokinetic studies in rats demonstrated that the oral bioavailability of SKLB610 in nanosuspension (89.4%) was 2.6-fold higher than in coarse suspension (34.1%). Stabilizer type, milling time, and milling speed had a significant effect on particle size of the SKLB610 nanosuspensions. Nanosuspensions effectively improved the dissolution rate and bioavailability of the water-insoluble drug SKLB610 by reducing the compound particle size to the nanoscale and employing a proper formulation.

Identification of novel 2-aminothiazole conjugated nitrofuran as antitubercular and antibacterial agents

The emergence of antibiotic resistant pathogens is an ongoing main problem in the therapy of bacterial infections. In order to develop promising antitubercular and antibacterial lead compounds, we designed and synthesized a new series of derivatives of 2-aminothiazole conjugated nitrofuran with activities against both Mycobacterium tuberculosis and Staphylococcus aureus. Eight compounds 12e, 12k, 12l, 12m, 18a, 18d, 18e, and 18j emerged as promising antitubercular agents. Structure-activity relationships (SARs) were discussed and showed that the derivatives substituted at the position-3 of benzene of 5-nitro-N-(4-phenylthiazol-2-yl)furan-2-carboxamide exhibited superior potency. The most potent compound 18e, substituted with benzamide at this position, displayed minimum inhibitory concentrations (MICs) of 0.27μg/mL against Mtb H37Ra and 1.36μg/mL against S. aureus. Furthermore, compound 18e had no obvious cytotoxicity to normal Vero cells (IC50=50.2μM). The results suggest that the novel scaffolds of aminothiazole conjugated nitrofuran would be a promising class of potent antitubercular and antimicrobial agents.

Benzothiazinethione is a potent preclinical candidate for the treatment of drug-resistant tuberculosis.

New chemotherapeutic compounds are needed to combat multidrug-resistant Mycobacterium tuberculosis (Mtb), which remains a serious public-health challenge. Decaprenylphosphoryl-β-D-ribose 2′-epimerase (DprE1 enzyme) has been characterized as an attractive therapeutic target to address this urgent demand. Herein, we have identified a new class of DprE1 inhibitors benzothiazinethiones as antitubercular agents. Benzothiazinethione analogue SKLB-TB1001 exhibited excellent activity against Mtb in the Microplate Alamar blue assay and intracellular model, meanwhile SKLB-TB1001 was also highly potent against multi-drug resistant extensively and drug resistant clinical isolates. Importantly, no antagonism interaction was found with any two-drug combinations tested in the present study and the combination of SKLB-TB1001 with rifampicin (RMP) was proved to be synergistic. Furthermore, benzothiazinethione showed superb in vivo antitubercular efficacy in an acute Mtb infection mouse model, significantly better than that of BTZ043. These data combined with the bioavailability and safety profiles of benzothiazinethione indicates SKLB-TB1001 is a promising preclinical candidate for the treatment of drug-resistant tuberculosis.

ZLD1122, a novel EZH2 and EZH1 small molecular inhibitor, blocks H3K27 methylation and diffuse large B cell lymphoma cell growth

The histone methyltransferase enhancer of zeste homolog 2 (EZH2) has been reported to be overexpressed in a variety of cancers and is associated with tumor malignancy. This is mainly because EZH2 catalyzes the hypertrimethylation of histone 3 at lysine 27 (H3K27) at the promoter of target genes, leading to the silencing of downstream tumor suppressor genes. Hence, blocking its catalytic function may be a therapeutic strategy for the treatment of tumors which over-express or have a gain-of-function mutation in EZH2, such as lymphomas. Here, we reported a novel, selective, small-molecule inhibitor of EZH2 and EZH1 synthesized by us, ZLD1122, which inhibited both EZH1 and wild type and mutant EZH2 activities with nanomolar potency. ZLD1122 significantly inhibited intracellular H3K27 trimethylation without affecting the levels of H3, H3K9me3, and H3K4me3, indicating its selective inhibition of polycomb repressive complex 2 (PRC2) methyl catalytic function. Moreover, ZLD1122 induced G0/G1 phase arrest in diffuse large B cell lymphoma (DLBCL) cells in a dose-dependent manner via downregulation of cyclinE and CDK4 as well as upregulation of p21 and cyclinD1. Furthermore, it induced apoptosis and loss of mitochondrial membrane potential (Δψm), and elevated the levels of cleaved caspase-9 in Su-DHL-6 and Pfeiffer cells, suggesting that ZLD1122 suppresses the viability of DLBCL cells by inducing caspase-mediated intrinsic apoptosis. Taken together, these data demonstrated that ZLD1122, owing to its pharmacologically inhibitory activity against EZH2, could be a promising agent for the treatment of lymphomas with EZH2 gain-of-function mutations.

Design, synthesis and biological evaluation of novel 1-methyl-3-oxo-2,3,5,6,7,8-hexahydroisoquinolins as potential EZH2 inhibitors

The histone lysine methyltransferase EZH2 has been implicated as a key component in cancer aggressiveness, metastasis and poor prognosis. This study discovered a new class of hexahydroisoquinolin derivatives as EZH2 inhibitors. A structure–activity relationship study showed that the steric hindrance was important to the activity for EZH2. A preliminary optimization study led to the discovery of several potent compounds with low nanomolar to sub-nanomolar potency for EZH2. Biological evaluation indicated that SKLB1049 was a highly potent with improved solubility compared to EPZ6438, SAM-competitive, and cell-active EZH2 inhibitor that decreased global H3K27me3 in SU-DHL-6 and Pfeiffer lymphoma cells in a concentration- and time-dependent manner. Further study indicated that SKLB1049 caused cell arrest in G0/G1 phase. These compounds would be useful as chemical tools to further explore the biology of EZH2 and provided us with a start point to develop new EZH2 inhibitors.