Design, Synthesis and Evaluation of Fluorescent Properties of Benzothiazole Derivatives.

Fluorescence imaging is conducive to establish a bridge between molecular biology and clinical medicine, and provides new tools for disease process research, early diagnosis, and efficacy evaluation, because of the advantages of rapid imaging and nondestructive detection. Herein, a series of fluorescent molecules with thiadiazole, or thiazole, or benzothiazole cores were designed and synthesized to develop more excellent fluorescent molecules in bio-imaging. According to theoretical and experimental methods, we found that benzothiazole derivative 14 B with conjugate expansion by (4-aminophenyl) ethynyl group was the most excellent fluorescent molecule among all the investigated compounds and exhibited low cytotoxicity and strong blue and green fluorescence by confocal cell imaging.

Theoretical study and application of 2-phenyl-1,3,4-thiadiazole derivatives with optical and inhibitory activity against SHP1.

Src homology-2 domain-containing protein tyrosine phosphatase 1 (SHP1) is mainly restricted to hematopoietic and epithelial cells and widely accepted as a convergent node for oncogenic cell-signaling cascades. The development of efficient methods for rapidly tracing and inhibiting the SHP1 activity in complex biological systems is of considerable significance for advancing the integration of diagnosis and treatment of the related disease. With this aim, we designed and synthesized five 2-phenyl-1,3,4-thiadiazole derivatives (PT2, PT5, PT8, PT9 and PT10) here based on the reported SHP1 inhibitors (PT1, PT3, PT4, PT6 and PT7). The photophysical properties and inhibitory activities of these 2-phenyl-1,3,4-thiadiazole derivatives (PT1-PT10) against SHP1 were thoroughly studied from the theoretical simulation and experimental application aspects. The representative compound PT10 exhibited a larger quantum yield than the other molecules because of the smaller geometric relaxation and reorganization energy of the excited state, which was consistent with the results from the fluorescence experiments in organic solvents. In addition, PT10 showed a selective fluorescence response for SHP1 activity and low cytotoxicity in HeLa cells. Lastly, it indicated the potential application in two-photon cell fluorescence imaging in the future according to the calculated excellent two-photon absorption properties. In this contribution, firstly, we offered the fluorescent and activated molecule PT10 against SHP1, which achieved the integration of visualization and inhibitory activity of SHP1 preliminarily at the enzyme molecular level.

Synthesis and Biochemical Evaluation of 8H-Indeno[1,2-d]thiazole Derivatives as Novel SARS-CoV-2 3CL Protease Inhibitors.

The COVID-19 pandemic caused by SARS-CoV-2 is a global burden on human health and economy. The 3-Chymotrypsin-like cysteine protease (3CLpro) becomes an attractive target for SARS-CoV-2 due to its important role in viral replication. We synthesized a series of 8H-indeno[1,2-d]thiazole derivatives and evaluated their biochemical activities against SARS-CoV-2 3CLpro. Among them, the representative compound 7a displayed inhibitory activity with an IC50 of 1.28 ± 0.17 µM against SARS-CoV-2 3CLpro. Molecular docking of 7a against 3CLpro was performed and the binding mode was rationalized. These preliminary results provide a unique prototype for the development of novel inhibitors against SARS-CoV-2 3CLpro.

Synthesis and biological evaluation of 2,5-diaryl-1,3,4-oxadiazole derivatives as novel Src homology 2 domain-containing protein tyrosine phosphatase 2 (SHP2) inhibitors.

The Src homology-2 domain containing-protein tyrosine phosphatase-2 (SHP2) is a convergent node for oncogenic cell-signaling cascades including the PD-L1/PD-1 pathway. As an oncoprotein as well as a potential immunomodulator, SHP2 has now emerged as an attractive target for novel anti-cancer agents. Although significant progress has been made in identifying chemotypes of SHP2 inhibitors, these specific compounds might not be clinically useful to inhibit frequently encountered mutated SHP2 variants. Consequently, it is highly desirable to develop chemically different SHP2 inhibitors sensitive to SHP2 mutants. This work developed a new type of SHP2 inhibitors with 2,5-diaryl-1,3,4-oxadiazole scaffold. The representative compound 6l exhibited SHP2 inhibitory activity with IC50 of 2.73 ± 0.20 µM, showed about 1.56-fold, 5.26-fold, and 7.36-fold selectivity for SHP2 over SHP1, PTP1B and TCPTP respectively. Further investigations confirmed that 6l behaved as mixed-type inhibitor sensitive to leukemia cell TF-1 and inhibited SHP2 mediated cell signaling and proliferation. Molecular dynamics simulation provided more detailed information on the binding modes of compounds and SHP2 protein. These preliminary results could provide a possible opportunity for the development of novel SHP2 inhibitors sensitive to SHP2 mutants with optimal potency and improved pharmacological properties.

Synthesis and biological evaluation of heterocyclic bis-aryl amides as novel Src homology 2 domain containing protein tyrosine phosphatase-2 (SHP2) inhibitors.

The Src homology-2 domain containing protein tyrosine phosphatase-2 (SHP2) is a convergent node for oncogenic cell-signaling cascades including the PD-L1/PD-1 pathway. Consequently, SHP2 has emerged as a compelling target for novel anti-cancer agents. Replacing one of phenyl ring in PTP1B inhibitor 1 with heterocyclic ring led to a series of heterocyclic bis-aryl amide derivatives. The representative compound 7b displayed SHP2 inhibitory activity with IC50 of 2.63 ± 0.08 µM, exhibited about 4-fold selectivity for SHP2 over TCPTP and had no detectable activity against SHP1 and PTP1B. These preliminary results could provide a possible opportunity for the development of novel SHP2 inhibitors with optimal potency and improved pharmacological properties.

Tim3/galectin-9 alleviates the inflammation of TAO patients via suppressing Akt/NF-kB signaling pathway.

Thyroid-associated ophthalmopathy (TAO) is an autoimmune disease. Studies showed that T helper 1 (Th1), Th2, and Th17 cells play important roles in the pathology of TAO. Tim-3 and its only known ligand Galectin-9 (Gal-9) is related to the suppression of Th1 and Th17 cytokine secretion. This study aims to investigate the role of Tim3/Gal-9 in the inflammatory response of TAO. In this study, the levels of Tim3, Gal-9, and cytokines of Th1 (TNF-α and IFN-γ), Th2 (IL-4), and Th17 (IL-17) cells were analyzed in the blood samples of TAO patients and healthy controls as well as in orbital fibroblasts. Tim3 overexpression and Gal-9 neutralizing antibody were used in TAO and LPS-stimulated control orbital fibroblasts to further investigate the role and mechanism of Tim3/Gal-9 on the inflammation of TAO. We found Tim3 and Gal-9 expression was significantly downregulated in TAO patients and further lower in active TAO than inactive TAO or controls. Th1, Th2, and Th17 cytokines were all increased in TAO patients. Th1 and Th17 cytokines were higher in active TAO patients than in inactive TAO patients, while Th2 cytokines were enhanced in inactive TAO. Tim3 overexpression decreased the levels of Th1 and Th17 cytokines, but not Th2 cytokine in TAO or LPS-stimulated control orbital fibroblasts. These effects were abrogated by Gal-9 neutralizing antibody. Moreover, Tim3 reduced the levels of p-Akt and p-p65 in TAO or LPS-induced control orbital fibroblasts that were reversed by Gal-9 blocking. In conclusion, Tim3/Gal-9 alleviates the inflammation of TAO patients via suppressing Akt/NF-κB signaling pathway.

Benzo[c][1,2,5]thiadiazole derivatives: A new class of potent Src homology-2 domain containing protein tyrosine phosphatase-2 (SHP2) inhibitors.

The Src homology-2 domain containing protein tyrosine phosphatase-2 (SHP2) is an oncogenic phosphatase linked to various kinds of cancers. Consequently, SHP2 has emerged as a promising target for novel anti-cancer agents. Using scaffold-hopping strategy, a series of benzo[c][1,2,5]thiadiazole derivatives was designed from PTP1B inhibitors with 1H-2,3-Dihydroperimidine motif, synthesized and evaluated their biological activities against PTP1B and SHP2. Among them, the representative compound 11g displayed SHP2 inhibitory activity with IC50 of 2.11 ±â€¯0.99 µM, exhibited 2.02-fold and 25-fold selectivity for SHP2 over SHP1 and PTP1B respectively and had no visible activity against TCPTP. These preliminary results could provide a possible opportunity for the development of novel SHP2 inhibitors with optimal potency and improved pharmacological properties.

Design, synthesis and in vitro activity of phidianidine B derivatives as novel PTP1B inhibitors with specific selectivity.

A series of phidianidine B derivatives were synthesized by introducing various heterocyclic rings. Their inhibitory effects on PTP1B and other PTPs (TCPTP, SHP1, SHP2 and LAR) were evaluated. A majority of them displayed significant inhibitory potency and specific selectivity over PTP1B. The SAR and molecular docking analysis were also described.

Curcusone D, a novel ubiquitin-proteasome pathway inhibitor via ROS-induced DUB inhibition, is synergistic with bortezomib against multiple myeloma cell growth.

BACKGROUND: Ubiquitin-proteasome pathway (UPP) plays a very important role in the degradation of proteins. Finding novel UPP inhibitors is a promising strategy for treating multiple myeloma (MM). METHODS: Ub-YFP reporter assays were used as cellular UPP models. MM cell growth, apoptosis and overall death were evaluated with the MTS assay, Annexin V/PI dual-staining flow cytometry, poly (ADP-ribose) polymerase (PARP) cleavage, and PI uptake, respectively. The mechanism of UPP inhibition was analyzed by western blotting for ubiquitin, in vitro and cellular proteasomal and deubiquitinases (DUBs) activity assays. Cellular reactive oxygen species (ROS) were measured with H2DCFDA. RESULTS: Curcusone D, identified as a novel UPP inhibitor, causes cell growth inhibition and apoptosis in MM cells. Curcusone D induced the accumulation of poly-ubiquitin-conjugated proteins but could not inhibit proteasomal activity in vitro or in cells. Interestingly, the mono-ubiquitin level and the total cellular DUB activity were significantly downregulated following curcusone D treatment. Furthermore, curcusone D could induce ROS, which were closely correlated with DUB inhibition that could be nearly completely reversed by NAC. Finally, curcusone D and the proteasomal inhibitor bortezomib showed a strong synergistic effect against MM cells. CONCLUSIONS: Curcusone D is novel UPP inhibitor that acts via the ROS-induced inhibition of DUBs to produce strong growth inhibition and apoptosis of MM cells and synergize with bortezomib. GENERAL SIGNIFICANCE: The anti-MM molecular mechanism study of curcusone D will promote combination therapies with different UPP inhibitors against MM and further support the concept of oxidative stress regulating the activity of DUBs.

Chlorabietols A-C, Phloroglucinol-Diterpene Adducts from the Chloranthaceae Plant Chloranthus oldhamii.

Three unprecedented phloroglucinol-diterpene adducts, chlorabietols A-C (1-3), were isolated from the roots of the rare Chloranthaceae plant Chloranthus oldhamii. They represent a new class of compounds, featuring an abietane-type diterpenoid coupled with different alkenyl phloroglucinol units by forming a 2,3-dihydrofuran ring. Their structures were elucidated by detailed spectroscopic analysis, molecular modeling studies, and electronic circular dichroism calculations. Compounds 1-3 showed inhibitory activity against protein tyrosine phosphatase 1B (PTP1B) with IC50 values of 12.6, 5.3, and 4.9 µM, respectively.

PTP1B inhibitors from stems of Angelica keiskei (Ashitaba).

Three new chalcones, xanthoangelols K-M (1-3), together with 19 known compounds were isolated from the stems of Angelica keiskei Koidzumi, a well-known rejuvenated and anti-diabetic plant originated from Japan. The structures of compounds 1-3 were elucidated on the basis of spectroscopic data and Mosher's method. All compounds were evaluated for their inhibitory activity against protein tyrosine phosphatase 1B (PTP1B). Among them, six chalcones, xanthoangelol K (1), xanthoangelol (4), xanthoangelol F (5), 4-hydroxyderricin (6), xanthoangelol D (7), xanthoangelol E (8), and a coumarin, methoxsalen (17), showed strong PTP1B inhibitory effect with IC50 values of 0.82, 1.97, 1.67, 2.47, 3.97, 1.43, and 2.53µg/mL, respectively. A kinetic study revealed that compound 1 inhibited PTP1B with characteristics typical of a competitive inhibitor. Molecular docking simulations elucidated that ring B of 1 may anchor in a pocket of PTP1B and the molecule is stabilized by hydrogen bonds with Arg47, Asp48, and π-π interaction with Phe182 of PTP1B.

Design and synthesis of novel 1,2-dithiolan-4-yl benzoate derivatives as PTP1B inhibitors.

A series of novel 1,2-dithiolan-4-yl benzoate compounds were synthesized and evaluated for in vitro PTP1B inhibitory activity. Some derivatives exhibited improved PTP1B inhibitory activity and selectivity compared to hit 6a, a compound from in-house library screening inspired by marine cyclic disulfide. The preliminary SAR analysis with assistance of molecular modeling approach revealed 6j (IC50=0.59µM) as the most potent PTP1B inhibitor among all derivatives.

New Isoprenylated Phenolic Compounds from Morus laevigata.

Two new isoprenylated flavonoids, laevigasins A and B (1 and 2, resp.), and one new isoprenylated 2-arylbenzofuran, leavigasin C (3), together with eight known compounds, 4-11, were isolated from the twigs of Morus laevigata. Their structures were elucidated by spectroscopic methods. Laevigasin A (1) showed significant inhibitory effect on α-glucosidase in vitro. Notabilisin E (5), taxifolin (10), and hultenin (11) inhibited PTP1B phosphatase activity in vitro.

Brominated polyunsaturated lipids with protein tyrosine phosphatase-1B inhibitory activity from Chinese marine sponge Xestospongia testudinaria.

A new brominated polyunsaturated lipid, methyl (E,E)-14,14-dibromo-4,6,13-tetradecatrienoate (1), along with three known related analogues (2-4), were isolated from the Et2O-soluble portion of the acetone extract of Chinese marine sponge Xestospongia testudinaria treated with diazomethane. The structure of the new compound was elucidated by detailed spectroscopic analysis and by comparison with literature data. Compound 3 exhibited significant inhibitory activity against protein tyrosine phosphatase 1B (PTP1B), a key target for the treatment of type II diabetes and obesity, with an IC50 value of 5.30 ± 0.61 µM, when compared to the positive control oleanolic acid (IC50 = 2.39 ± 0.26 µM).

Synthesis and biological evaluation of novel bis-aromatic amides as novel PTP1B inhibitors.

A series of bis-aromatic amides was designed, synthesized, and evaluated as a new class of inhibitors with IC50 values in the micromolar range against protein tyrosine phosphatase 1B (PTP1B). Among them, compound 15 displayed an IC50 value of 2.34±0.08 µM with 5-fold preference over TCPTP. More importantly, the treatment of CHO/HIR cells with compound 15 resulted in increased phosphorylation of insulin receptor (IR), which suggested extensive cellular activity of compound 15. These results provided novel lead compounds for the design of inhibitors of PTP1B as well as other PTPs.

Design and synthesis of paracaseolide A analogues as selective protein tyrosine phosphatase 1B inhibitors.

A series of structurally related analogues of the natural product paracaseolide A were synthesized and identified as potent PTP1B inhibitors. Among these analogues, compound 10 in particular showed improved PTP1B enzyme inhibitory activity, high selectivity for PTP1B over TC-PTP, and improved cellular effects.

4-Quinolone-3-carboxylic acids as cell-permeable inhibitors of protein tyrosine phosphatase 1B.

Protein tyrosine phosphatase 1B is a negative regulator in the insulin and leptin signaling pathways, and has emerged as an attractive target for the treatment of type 2 diabetes and obesity. However, the essential pharmacophore of charged phosphotyrosine or its mimetic confer low selectivity and poor cell permeability. Starting from our previously reported aryl diketoacid-based PTP1B inhibitors, a drug-like scaffold of 4-quinolone-3-carboxylic acid was introduced for the first time as a novel surrogate of phosphotyrosine. An optimal combination of hydrophobic groups installed at C-6, N-1 and C-3 positions of the quinolone motif afforded potent PTP1B inhibitors with low micromolar IC50 values. These 4-quinolone-3-carboxylate based PTP1B inhibitors displayed a 2-10 fold selectivity over a panel of PTP's. Furthermore, the bidentate inhibitors of 4-quinolone-3-carboxylic acids conjugated with aryl diketoacid or salicylic acid were cell permeable and enhanced insulin signaling in CHO/hIR cells. The kinetic studies and molecular modeling suggest that the 4-quinolone-3-carboxylates act as competitive inhibitors by binding to the PTP1B active site in the WPD loop closed conformation. Taken together, our study shows that the 4-quinolone-3-carboxylic acid derivatives exhibit improved pharmacological properties over previously described PTB1B inhibitors and warrant further preclinical studies.

Novel imidazo[1,2,4] triazole derivatives: Synthesis, fluorescence, bioactivity for SHP1.

The Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP1) is a convergent node for oncogenic cell-signaling cascades. Consequently, SHP1 represents a potential target for drug development in cancer treatment. The development of efficient methods for rapidly tracing and modulating the SHP1 activity in complex biological systems is of considerable significance for advancing the integration of diagnosis and treatment of the related disease. Thus, we designed and synthesized a series of imidazo[1,2,4] triazole derivatives containing salicylic acid to explore novel scaffolds with inhibitory activities and good fluorescence properties for SHP1. The photophysical properties and inhibitory activities of these imidazo[1,2,4] triazole derivatives (5a-5y) against SHP1PTP were thoroughly studied from the theoretical simulation and experimental application aspects. The representative compound 5p exhibited remarkable fluorescence response (P: 0.002) with fluorescence quantum yield (QY) of 0.37 and inhibitory rate of 85.21 ± 5.17% against SHP1PTP at the concentration of 100 µM. Furthermore, compound 5p showed obvious aggregation caused quenching (ACQ) effect and had high selectivity for Fe3+ ions, good anti-interference and relatively low detection limit (5.55 µM). Finally, the cellular imaging test of compound 5p also exhibited good biocompatibility and certain potential biological imaging application. This study provides a potential way to develop molecules with fluorescent properties and bioactivities for SHP1.

Synthesis, Fluorescence, and Bioactivity of Novel Isatin Derivatives.

The isatin group is widespread in nature and is considered to be a privileged building block for drug discovery. In order to develop novel SHP1 inhibitors with fluorescent properties as tools for SHP1 biology research, this work designed and synthesized a series of isatin derivatives. The presentive compound 5a showed good inhibitory activity against SHP1PTP with IC50 of 11 ± 3 µM, displayed about 92% inhibitory rate against MV-4-11 cell proliferation at the concentration of 20 µM, exhibited suitable fluorescent properties with a long emission wavelength and a large Stokes shift, and presented blue fluorescent imaging in HeLa cells with low cytotoxicity. This study could offer chemical tool to further understand SHP1 biology and develop novel SHP1 inhibitors in therapy.

The first synthesis of natural disulfide bruguiesulfurol and biological evaluation of its derivatives as a novel scaffold for PTP1B inhibitors.

Bruguiesulfurol (1), a cyclic 4-hydroxy-dithiosulfonate isolated from mangrove plant Bruguiera gymnorrhiza, was concisely synthesized for the first time in four steps, and a series of its synthetic derivatives were evaluated for in vitro inhibitory effects on PTP1B and related PTPs. Some derivatives were found to have improved pharmacological profile compared with hit 1. Among them, 5a showed the potent selectivity towards PTP1B over other PTPs, including TCPTP, and 7j exhibited the strongest PTP1B inhibitory activity with an IC50 value of 4.54 µM.