Synthesis and biological evaluation of isatin derivatives containing 1,3,4-thiadiazole as potent a-glucosidase inhibitors.

A series of (Z)-3-(2-(1,3,4-thiadiazol-2-yl)hydrazono)-1-substituted indolin-2-ones derivatives (3a-3m) were designed and synthesized. All newly synthesized compounds were evaluated for their a-glucosidase inhibitory activity with resveratrol as positive control in vitro. Except for 3i and 3j, all of the compounds showed a potent inhibitory activity against a-glucosidase with IC50 values in the range of 3.12 ± 1.25 to 45.95 ± 1.26 µM and the purity of these compounds was greater than 95%. The IC50 values were being compared to the standard resveratrol (IC50 = 22.00 ± 1.15 µM) and it was found that compounds 3b, 3d-3h were found to be more active than resveratrol. Specifically, (Z)-3-(2-(1,3,4-thiadiazol-2-yl)hydrazono)-1-(4-chlorobenzyl)indolin-2-one (3d) exhibited the most potent a-glucosidase inhibitory activity with IC50 value of 3.12 ± 1.25 µM. The kinetic analysis revealed that compound (3d) is noncompetitive inhibitor. Structure activity relationship has been established for all compounds. Furthermore, the binding interactions of compound 3d with the active site of a-glucosidase were confirmed through molecular docking. This study has identified a new class of potent a-glucosidase inhibitors for further investigation.

Mitochondria-targeted phosphorescent cyclometalated iridium(III) complexes: synthesis, characterization, and anticancer properties.

Cyclometalated iridium(III) complexes represent a promising approach to developing new anticancer metallodrugs. In this work, three phosphorescent cyclometalated iridium(III) complexes Ir1-Ir3 have been explored as mitochondria-targeted anticancer agents. All three complexes display higher antiproliferative activity than cisplatin against the cancer cells screened, and with the IC50 values ranging from 0.23 to 5.6 µM. Colocalization studies showed that these complexes are mainly localized in the mitochondria. Mechanism studies show that these complexes exert their anticancer efficacy through initiating a series of events related to mitochondrial dysfunction, including depolarization of mitochondrial membrane potential (MMP), elevation of intracellular reactive oxygen species (ROS) levels, and induction of apoptosis. Mitochondria-targted cyclometalated iridium complexes induce apoptosis through depolarized mitochondria, elevation of intracellular ROS and activated caspase.

Discovery of novel indazole-acylsulfonamide hybrids as selective Mcl-1 inhibitors.

Overexpressing myeloid cell leukemia sequence 1 (Mcl-1) protein is an important way to confer the resistance of cancer cells to conventional anti-cancer treatments. Therefore, developing Mcl-1 inhibitors has become an attractive strategy for cancer therapy. In the studies, a series of new indazole-acylsulfonamide hybrids were designed, synthesized and evaluated as potent Mcl-1 inhibitors. Among them, the most potent compound 17 (Ki = 0.43 µM) showed a little better inhibitory activity against Mcl-1 protein than positive control AT-101 (Ki = 0.45 µM). Pleasingly, it displayed > 40-fold selectivity over Bcl-2 (Ki = 18 µM) and Bcl-xL (no activity). Furthermore, compound 17 had good inhibitory activities against PC-3, MDA-MB-231 and K562 cells (IC50 = 12.3, 10.6 and 6.62 µM, respectively) and could effectively induce apoptosis and the activation of caspase-3 in a dose-dependent manner in K562 cells.

Opportunities and challenges of using five-membered ring compounds as promising antitubercular agents.

Tuberculosis (TB), a chronic infectious disease, is one of the greatest risks to human beings and 10 million people were diagnosed with TB and 1.6 million died from this disease in 2017. In addition, with the emergence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB), the TB situation has become even worse, which has aggravated the mortality and spread of this disease. To overcome this problem, research into novel antituberculosis agents with enhanced activities against MDR-TB, reduced toxicity, and shortened duration of therapy is of great importance. Fortunately, many novel potential anti-TB drug candidates with five-membered rings, which are most likely to be effective against sensitive and resistant strains, have recently entered clinical trials. Different five-membered rings such as furans, pyranoses, thiazoles, pyrazolines, imidazoles, oxazolidinone, thiazolidins, isoxazoles, triazoles, oxadiazoles, thiadiazoles, and tetrazoles have been designed, prepared, and evaluated for their antimycobacterial activity against Mycobacterium tuberculosis. In this article, we highlight the recent advances made in the discovery of novel five-membered ring compounds and focus on their antitubercular activities, toxicity, structure-activity relationships, and mechanisms of action.

Design, synthesis, fungicidal activity and molecular docking studies of novel 2-((2-hydroxyphenyl)methylamino)acetamide derivatives.

A series of novel 2-hydroxyphenyl substituted aminoacetamides was designed by molecular hybridization of the aminoacetamide scaffold and 2-hydroxyphenyl motif. The target compounds were synthesized and their fungicidal activities were evaluated. Some of the target compounds showed excellent antifungal activities against S. sclerotiorum and P. capsici. Significantly, compounds 5e displayed the most potent activity against S. sclerotiorum with EC50 = 2.89 µg/mL, which was lower than that of commercial chlorothalonil. The systematic studies provided strong confidence that the hydroxyl group and the carbonyl group are crucial for the fungicidal activity. Molecular docking studies suggest that SDH enzyme could be one of the potential action targets of our compounds.

Discovery and development of substituted tyrosine derivatives as Bcl-2/Mcl-1 inhibitors.

Anti-apoptotic Bcl-2 family proteins are vital for cancer cells to escape apoptosis, which make them attractive targets for cancer therapy. Recently, a lead compound 1 was found to modestly inhibit the binding of BH3 peptide to Bcl-2 protein with a Ki value of 5.2 µM. Based on this, a series of substituted tyrosine derivatives were developed and tested for their binding affinities to Bcl-2 protein. Results indicated that these compounds exhibited potent binding affinities to Bcl-2 and Mcl-1 protein but not to Bcl-XL protein. Promisingly, compound 6i inhibited the binding of BH3 peptide to Bcl-2 and Mcl-1 protein with a Ki value of 450 and 190 nM respectively, and showed obvious anti-proliferative activities against tested cancer cells.

Discovery of a Turn-On Fluorescent Probe for Myeloid Cell Leukemia-1 Protein.

The environment-sensitive probe 2 with turn-on switch for Mcl-1 protein was developed herein. After careful evaluation, this small molecule fluorescent probe revealed a selective binding affinity with Mcl-1 protein with a Ki value of 2.6 µM and can be well applied to imaging Mcl-1 protein or detecting the cellular distribution of Mcl-1 protein inhibitors. Compared with other imaging approaches, such as the immunofluorescence and fluorescent protein-based techniques, this fluorescent method is rapid, convenient, and affordable, especially since a washing procedure is no longer needed. This environment-sensitive "off-on" design strategy may present a case in point for developing small-molecule fluorescent probe of Bcl-2 family proteins.

Improved binding affinities of pyrrolidine derivatives as Mcl-1 inhibitors by modifying amino acid side chains.

As an important member of anti-apoptotic Bcl-2 protein, myeloid cell leukemia sequence 1 (Mcl-1) protein is an attractive target for cancer therapy. In this study, a new series of pyrrolidine derivatives as Mcl-1 inhibitors were developed by mainly modifying the amino acid side chain of compound 1. Among them, compound 18 (Ki=0.077µM) exhibited better potent inhibitory activities towards Mcl-1 protein compared to positive control Gossypol (Ki=0.18µM). In addition, compound 40 possessed good antiproliferative activities against PC-3 cells (Ki=8.45µM), which was the same as positive control Gossypol (Ki=7.54µM).

Design, synthesis and preliminary biological evaluation of indole-3-carboxylic acid-based skeleton of Bcl-2/Mcl-1 dual inhibitors.

The B-cell lymphoma-2 (Bcl-2) family proteins are attractive targets for cancer therapy. In our previous work, the structure-activity relationship of WL-276 was studied. According to the results, rhodanine derivatives show potent binding affinity for Bcl-2 and Mcl-1 protein and show weaker activity against Bcl-XL protein. Based on the previous results, a new class of indole-3-carboxylic acid-based derivatives were designed and synthesized as Bcl-2/Mcl-1 dual inhibitors. Among them, compound 17 has a Ki value of 0.26µM for Bcl-2 protein and is better than WL-276. Furthermore, it inhibits the myeloid cell leukemia sequence 1 (Mcl-1) protein with a Ki value of 72nM. Especially, compound 31 can selectively acting on Bcl-2 and Mcl-1 protein but not Bcl-XL protein, which has great significance for developing dual inhibitors targeting Bcl-2 and Mcl-1 protein, as well as specific antitumor abilities in cells.

Synthesis and Fungicidal Activity of 1-(Carbamoylmethyl)-2-aryl-3,1-benzoxazines.

A series of new 1-(carbamoylmethyl)-2-aryl-3,1-benzoxazines were prepared in moderate to good yields by BF3·OEt2-catalyzed reactions of aromatic aldehydes with 2-(N-substituted carbamoylmethylamino)benzyl alcohols. The structures of the target compounds were confirmed by IR, ¹H-NMR, 13C-NMR, and elemental analyses. The fungicidal activities of the target compounds against plant fungi were preliminarily evaluated, and some of them exhibited good activity.

Design, synthesis and preliminary biological studies of pyrrolidine derivatives as Mcl-1 inhibitors.

Anti-apoptotic proteins, such as B-cell lymphoma (Bcl-2) protein, myeloid cell leukemia sequence 1 (Mcl-1) protein, are potential targets for cancer treatment. In the studies, a series of pyrrolidine derivatives were developed as potent Mcl-1 inhibitors. The preliminary biological studies suggested that most of target compounds exhibit good abilities for targeting Mcl-1 protein. Among them, compound 21 (Ki=0.53µM) exhibited equal inhibitory activities towards Mcl-1 protein compared to positive control gossypol (Ki=0.39µM). This compound also possessed good antiproliferative activities against MDA-MB-231 and PC-3 cancer cells.

Design, synthesis and preliminary bioactivity studies of 2-thioxo-4-thiazolidinone derivatives as Bcl-2 inhibitors.

The B-cell lymphoma-2 (Bcl-2) protein is a promising target for cancer therapy. In the present study, a series of 2-thioxo-4-thiazolidinone derivatives were designed and synthesized as Bcl-2 inhibitors. Most of them possessed decent inhibitory activity for anti-apoptotic Bcl-2 proteins. Among them, compound 31 has similar growth inhibition towards K562 compared to (R)-Gossypol. In addition, it inhibits the myeloid cell leukemia sequence 1 (Mcl-1) protein with a Ki value of 74 nM.

Improved antiproliferative activity of 1,3,4-thiadiazole-containing histone deacetylase (HDAC) inhibitors by introduction of the heteroaromatic surface recognition motif.

A series of 1,3,4-thiadiazole-containing hydroxamic acids, in accord with the common pharmacophore of histone deacetylase (HDAC) inhibitors (a Zn(2+) binding moiety-a linker-a surface recognition motif), was identified as submicromolar HDAC inhibitors by our group. In this study, we continued our efforts to develop 1,3,4-thiadiazole bearing hydroxamate analogues by modifying the surface recognition motif. We found that 1,3,4-thiadiazoles having a heteroaromatic substituent showed better HDAC inhibitory activity in enzymatic assay and higher antiproliferative potency in cellular assay compared to SAHA.

Construction and catalysis role of a kinetic promoter based on lithium-insertion technology and proton exchange strategy for lithium-sulfur batteries.

The high theoretical energy density and specific capacity of lithium-sulfur (Li-S) batteries have garnered considerable attention in the prospective market. However, ongoing research on Li-S batteries appears to have encountered a bottleneck, with unresolved key technical challenges such as the significant shuttle effect and sluggish reaction kinetics. This investigation explores the catalytic efficacy of three catalysts for Li-S batteries and elucidates the correlation between their structure and catalytic impacts. The results suggest that the combined utilization of lithium-insertion technology and a proton exchange approach for δ-MnO2 can optimize its electronic structure, resulting in an optimal catalyst (H/Li inserted δ-MnO2, denoted as HLM) for the sulfur reduction reaction. The replacement of Mn sites in δ-MnO2 with Li atoms can enhance the structural stability of the catalyst, while the introduction of H atoms between transition metal layers contributes to the satisfactory catalytic performance of HLM. Theoretical calculations demonstrate that the bond length of Li2S4 adsorbed by the HLM molecule is elongated, thereby facilitating the dissociation process of Li2S4 and enhancing the reaction kinetics in Li-S batteries. Consequently, the Li-S battery utilizing HLM as a catalyst achieves a high areal specific capacity of 4.2 mAh cm-2 with a sulfur loading of 4.1 mg cm-2 and a low electrolyte/sulfur (E/S) ratio of 8 µL mg-1. This study introduces a methodology for designing effective catalysts that could significantly advance practical developments in Li-S battery technology.

Benzoxazine: A Privileged Scaffold in Medicinal Chemistry.

BACKGROUND: Benzoxazine is one of the most important privileged scaffolds in medicinal chemistry. Compounds bearing benzoxazine moiety usually have a variety of biological activities, such as anti-inflammatory, anti-microbial, anti-tuberculosis, anti- oxidant and anti-cancer activities. The fascinating bioactivity profile of benzoxazine scaffold in various fields has prompted medicinal chemists to design and discover novel benzoxazine derivatives as potential therapeutic candidates with the desired biological properties. OBJECTIVE: This review aimed to provide a comprehensive elucidation on the recent advances of benzoxazine derivatives in medicinal chemistry. METHODS: We have searched the recent literature about benzoxazine derivatives from the online resources and databases, such as PubMed, SciFinder and Google Scholar. RESULTS: Many benzoxazine derivatives with a wide range of bioactivities, such as anti- microbial, anti-cancer, anti-tuberculosis, anti-oxidant and anti-inflammatory, were summed up. Many compounds displayed good biological activities. CONCLUSION: Benzoxazine is a versatile structure and building block in medicinal chemistry. Benzoxazine derivatives have gained considerable attention from medicinal chemists due to their various pharmacological properties and multiple modification sites. This review might help medicinal chemists to seek new drug candidates with better bioactivities and pharmacokinetics properties.

Azaindole derivatives as potential kinase inhibitors and their SARs elucidation.

Currently, heterocycles have occupied an important position in the fields of drug design. Among them, azaindole moiety is regarded as one privileged scaffold to develop therapeutic agents. Since two nitrogen atoms of azaindole increase the possibility to form hydrogen bonds in the adenosine triphosphate (ATP)-binding site, azaindole derivatives are important sources of kinase inhibitors. Moreover, some of them have been on the market or in clinical trials for the treatment of some kinase-related diseases (e.g., vemurafenib, pexidartinib, decernotinib). In this review, we focused on the recent development of azaindole derivatives as potential kinase inhibitors based on kinase targets, such as adaptor-associated kinase 1 (AAK1), anaplastic lymphoma kinase (ALK), AXL, cell division cycle 7 (Cdc7), cyclin-dependent kinases (CDKs), dual-specificity tyrosine (Y)-phosphorylation regulated kinase 1A (DYRK1A), fibroblast growth factor receptor 4 (FGFR4), phosphatidylinositol 3-kinase (PI3K) and proviral insertion site in moloney murine leukemia virus (PIM) kinases. Meanwhile, the structure-activity relationships (SARs) of most azaindole derivatives were also elucidated. In addition, the binding modes of some azaindoles complexed with kinases were also investigated during the SARs elucidation. This review may offer an insight for medicinal chemists to rationally design more potent kinase inhibitors bearing the azaindole scaffold.

2-Aminothiazole: A privileged scaffold for the discovery of anti-cancer agents.

Cancer has been the second heath killer being next only to cardiovascular diseases in human society. Although many efforts have been taken for cancer therapy and many achievements have been yielded in the diagnosis and treatment of cancer, the current first-line anti-cancer agents are insufficient owing to the emergence of multi-drug resistance and side effects. Therefore, it is urgent to develop new anti-cancer agents with high activity and low toxicity. 2-Aminothiazole is a class of important scaffold which widely distributes in many natural and synthetic compounds with many pharmacological effects including the potential anti-cancer activity. In this review, we summarized the recent progress of 2-aminothiazole as a privileged scaffold for the discovery of anti-cancer agents based on biological targets, such as tubulin protein, histone acetylase/histone deacetylase (HAT/HDAC), phosphatidylinositol 3-kinases (PI3Ks), Src/Abl kinase, BRAF kinase, epidermal growth factor receptor (EGFR) kinase and sphingosine kinase (SphK), and also investigated the structure-activity relationships (SARs) of most compounds. It is believed that this review could be helpful for medicinal chemists in the discovery of more anti-cancer agents bearing 2-aminothiazole scaffold with excellent activity and high therapeutic index.

Sulfonamide derivatives as potential anti-cancer agents and their SARs elucidation.

Currently, the arise of drug resistance and undesirable off-target effects of anti-cancer agents are major challenges for cancer treatment, which energizes medicinal chemists to develop more anti-cancer agents with high efficiency and low toxicity continuously. Sulfonamide derivatives are a class of promising compounds with diverse biological activities including anti-cancer, and parts of them have been marketed for cancer therapy, such as Belinostat, ABT-199 and Amsacrine. In this review, we summed up the recent advances of sulfonamide derivatives as potential anti-cancer agents based on the anti-cancer targets, such as aromatase, carbonic anhydrase (CA), anti-apoptotic B-cell lymphoma-2 (Bcl-2) proteins, topoisomerase and phosphatidylinositol 3-kinase (PI3K), and elucidated the corresponding structure-activity relationships (SARs) of most sulfonamide derivatives. We hope this review could provide a clear insight for medicinal chemists in the rational design of more potent and bio-target specific anti-cancer agents.

Dual-target Inhibitors Based on BRD4: Novel Therapeutic Approaches for Cancer.

BACKGROUND: Currently, cancer continues being a dramatically increasing and serious threat to public health. Although many anti-tumor agents have been developed in recent years, the survival rate of patients is not satisfactory. The poor prognosis of cancer patients is closely related to the occurrence of drug resistance. Therefore, it is urgent to develop new strategies for cancer treatment. Multi-target therapies aim to have additive or synergistic effects and reduce the potential for the development of resistance by integrating different pharmacophores into a single drug molecule. Given the fact that majority of diseases are multifactorial in nature, multi-target therapies are being exploited with increasing intensity, which has brought improved outcomes in disease models and obtained several compounds that have entered clinical trials. Thus, it is potential to utilize this strategy for the treatment of BRD4 related cancers. This review focuses on the recent research advances of dual-target inhibitors based on BRD4 in the aspect of anti-tumor. METHODS: We have searched the recent literatures about BRD4 inhibitors from the online resources and databases, such as pubmed, elsevier and google scholar. RESULTS: In the recent years, many efforts have been taken to develop dual-target inhibitors based on BRD4 as anti-cancer agents, such as HDAC/BRD4 dual inhibitors, PLK1/BRD4 dual inhibitors and PI3K/BRD4 dual inhibitors and so on. Most compounds display good anti-tumor activities. CONCLUSION: Developing new anti-cancer agents with new scaffolds and high efficiency is a big challenge for researchers. Dual-target inhibitors based on BRD4 are a class of important bioactive compounds. Making structural modifications on the active dual-target inhibitors according to the corresponding structure-activity relationships is of benefit to obtain more potent anti-cancer leads or clinical drugs. This review will be useful for further development of new dual-target inhibitors based on BRD4 as anti-cancer agents.

Small-molecule PROTACs: novel agents for cancer therapy.

Proteolysis-targeting chimera (PROTAC) is a new technology to selectively degrade target proteins via ubiquitin-proteasome system. PROTAC molecules (PROTACs) are a class of heterobifunctional molecules, which contain a ligand targeting the protein of interest, a ligand recruiting an E3 ligase and a linker connecting these two ligands. They provide several advantages over traditional inhibitors in potency, selectivity and drug resistance. Thus, many promising PROTACs have been developed in the recent two decades, especially small-molecule PROTACs. In this review, we briefly introduce the mechanism of PROTACs and focus on the progress of small-molecule PROTACs based on different E3 ligases. In addition, we also introduce the opportunities and challenges of small-molecule PROTACs for cancer therapy.