Synthesis and Evaluation of Chiral Rhodanine Derivatives Bearing Quinoxalinyl Imidazole Moiety as ALK5 Inhibitors

Application of 18β-glycyrrhetinic acid in the structural modification of natural products: a review

18β-Glycyrrhetinic acid (GA) is an oleane-type pentacyclic triterpene saponin obtained from glycyrrhizic acid by removing 2 glucuronic acid groups. GA and its analogues are active substances of glycyrrhiza aicd, with similar structure and important pharmacological effects such as anti-inflammatory, anti-diabetes, anti-tumor and anti-fibrosis. Although GA combined compounds are in the clinical trial stages, its application potential is severely restricted by its low bioavailability, water solubility and membrane permeability. In this article, synthetic methods and structure-activity relationships (SARs) of GA derivatives from 2018 to present are reviewed based on pharmacological activity. It is hoped that this review can provide reference for the future development of potential GA preclinical candidate compounds, and furnish ideas for the development of pentacyclic triterpenoid lead compounds.

Synthesis of amide derivatives containing the imidazole moiety and evaluation of their anti-cardiac fibrosis activity

Three series of N-{[4-([1,2,4]triazolo[1,5-α]pyridin-6-yl)-5-(6-methylpyridin-2-yl)-1H-imidazol-2-yl]methyl}acetamides (14a-d, 15a-n, and 16a-f) were synthesized and evaluated for activin receptor-like kinase 5 (ALK5) inhibitory activities in an enzymatic assay. The target compounds showed high ALK5 inhibitory activity and selectivity. The half maximal inhibitory concentration (IC50) for phosphorylation of ALK5 of 16f (9.1 nM), the most potent compound, was 2.7 times that of the clinical candidate EW-7197 (vactosertib) and 14 times that of the clinical candidate LY-2157299. The selectivity index of 16f against p38α mitogen-activated protein kinase was >109, which was much higher than that of positive controls (EW-7197: >41, and LY-2157299: 4). Furthermore, a molecular docking study provided the interaction modes between the target compounds and ALK5. Compounds 14c, 14d, and 16f effectively inhibited the protein expression of α-smooth muscle actin (α-SMA), collagen I, and tissue inhibitor of metalloproteinase 1 (TIMP-1)/matrix metalloproteinase 13 (MMP-13) in transforming growth factor-β-induced human umbilical vein endothelial cells. Compounds 14c and 16f showed especially high activity at low concentrations, which suggests that these compounds could inhibit myocardial cell fibrosis. Compounds 14c, 14d, and 16f are potential preclinical candidates for the treatment of cardiac fibrosis.

Synthesis and anti-liver fibrosis activity of imidazole and thiazole compounds containing amino acids

Four series of imidazoles (15a-g, 20c, and 20d) and thiazoles (18a-g, 22a, and 22b) possessing various amino acids were synthesized and evaluated for activin receptor-like kinase 5 (ALK5) inhibitory activities in an enzymatic assay. Among them, compounds 15g and 18c showed the highest inhibitory activity against ALK5, with IC50 values of 0.017 and 0.025 μM, respectively. Compounds 15g and 18c efficiently inhibited extracellular matrix (ECM) deposition in TGF-β-induced hepatic stellate cells (HSCs), and eventually suppressed HSC activation. Moreover, compound 15g showed a good pharmacokinetic (PK) profile with a favorable half-life (t1/2 = 9.14 h). The results indicated that these compounds exhibited activity targeting ALK5 and may have potential in the treatment of liver fibrosis; thus they are worthy of further study.

Synthesis and Antimicrobial Activity Evaluation of Pyridine Derivatives Containing Imidazo[2,1-b][1,3,4]Thiadiazole Moiety

Four series of novel pyridine derivatives (17 a-i, 18 a-i, 19 a-e, and 20 a-e) were synthesized and their antimicrobial activities were evaluated. Of all the target compounds, almost half target compounds showed moderate or high antibacterial activity. The 4-F substituted compound 17 d (MIC=0.5 μg/mL) showed the highest antibacterial activity, its activity was twice the positive control compound gatifloxacin (MIC=1.0 μg/mL). For fungus ATCC 9763, the activities of compounds 17 a and 17 d are equivalent to the positive control compound fluconazole (MIC=8 μg/mL). Furthermore, compounds 17 a and 17 d showed little cytotoxicity to human LO2 cells, and did not show hemolysis even at ultra-high concentration (200 μM). The results indicate that these compounds are valuable for further development as antibacterial and antifungal agents.

Synthesis and Evaluation of Imidazole Derivatives Bearing Imidazo[2,1-b] [1,3,4]thiadiazole Moiety as Antibacterial Agents

BACKGROUND

Drug-resistant infections kill hundreds of thousands of people globally every year. In previous work, we found that tri-methoxy- and pyridine-substituted imidazoles show strong antibacterial activities.

OBJECTIVE

The aim of this work was to investigate the antibacterial activities and bacterial resistances of imidazoles bearing an aromatic heterocyclic, alkoxy, or polycyclic moiety on the central ring.

METHODS

Three series of 2-cyclopropyl-5-(5-(6-methylpyridin-2-yl)-2-substituted-1H-imidazol-4- yl)-6-phenylimidazo[2,1-b][1,3,4]thiadiazoles (13a-e, 14a-d, and 15a-f) were synthesized and their antibacterial activity was evaluated. The structures were confirmed by their 1H NMR, 13C NMR, and HRMS spectra. All the synthesized compounds were screened against Gram-positive, Gramnegative, and multidrug-resistant bacterial strains.

RESULTS

More than half of the compounds showed moderate or strong antibacterial activity. Among them, compound 13e (MICs = 1-4 μg/mL) showed the strongest activity against Gram-positive and drug-resistant bacteria as well as high selectivity against Gram-negative bacteria. Furthermore, it showed no cytotoxicity against HepG2 cells, even at 100 μM, and no hemolysis at 20 μM.

CONCLUSION

These results indicate that compound 13e is excellent candicate for further study as a potential antibacterial agent.

Recent Advances in Research on Active Compounds Against Hepatic Fibrosis

BACKGROUND

Almost all chronic liver diseases cause fibrosis, which can lead to cirrhosis and eventually liver cancer. Liver fibrosis is now considered to be a reversible pathophysiological process and suppression of fibrosis is necessary to prevent liver cancer. At present, no specific drugs have been found that have hepatic anti-fibrotic activity.

OBJECTIVE

The research progress of anti-hepatic fibrosis compounds in recent ten years was reviewed to provide a reference for the design and development of anti-hepatic fibrosis drugs.

METHODS

According to the structure of the compounds, they are divided into monocyclic compounds, fused-heterocyclic compounds, and acyclic compounds.

RESULTS

In this article, the natural products and synthetic compounds with anti-fibrotic activity in recent ten years were reviewed, with emphasis on their pharmacological activity and structure-activity relationship (SAR).

CONCLUSION

Most of these compounds are natural active products and their derivatives, and there are few researches on synthetic compounds and SAR studies on natural product.

Discovery of Triazolyl Derivatives of Cucurbitacin B Targeting IGF2BP1 against Non-Small Cell Lung Cancer

Cucurbitacin B (CuB) is a potent but toxic anticancer natural product. Herein, we designed and synthesized 2-OH- and 16-OH-modified CuB derivatives to improve their antitumor efficacy and reduce toxicity. Among them, derivative A11 had the most potent antiproliferative activity against A549 lung cancer cells (IC50 = 0.009 μM) and was approximately 10-fold more potent than CuB, while the cytotoxicity of A11 toward normal L02 cells was about 10-fold less potent, indicating a much wider therapeutic window than CuB. Derivative A11 directly binds to the insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) protein with a KD value of 2.88 nM, which is about 23-fold more potent than CuB, leading to the decreased expression of downstream apoptosis- and cell cycle-related proteins. More importantly, A11 exhibited much more potent anticancer efficacy in an A549 xenograft mouse model with a TGI rate of 80% and a superior in vivo safety profile than that of CuB.

Synthesis and antimicrobial activity evaluation of pyrazole derivatives containing the imidazo[2,1-b][1,3,4]thiadiazole moiety

Four series of novel pyrazole derivatives (compounds 17a-m, 18a-m, 19a-g, and 20a-g) were synthesized, and their antibacterial and antifungal activities were evaluated. Most of the target compounds (17a-m, 18k-m, and 19b-g) showed strong antifungal activity and high selectivity relative to both Gram-positive and Gram-negative bacteria. Among them, compounds 17l (minimum inhibitory concentration [MIC] = 0.25 µg/mL) and 17m (MIC = 0.25 µg/mL) showed the strongest antifungal activity, being 2- and 4-fold more active than the positive controls gatifloxacin and fluconazole, respectively. In particular, compound 17l showed little cytotoxicity against human LO2 cells and did not exhibit hemolysis at ultrahigh concentrations, as did the positive control compounds gatifloxacin and fluconazole. These results indicate that these compounds are valuable for further development as antifungal agents.

Rhodanine derivatives: An insight into the synthetic and medicinal perspectives as antimicrobial and antiviral agents

Rhodanine or 2-Thioxothiazolidin-4-one is a privileged heterocyclic compound offering a wide opportunity for structural modification, lead development, and modification. It is one of the highly decorated scaffolds in the drug discovery process. Rhodanine derivatives possess a plethora of biological activities due to their ability to interact with a diverse range of protein targets, which provide tremendous opportunities to discover new drugs with different modes of action. The most common strategy for developing novel rhodanine derivatives is the introduction of structurally diverse substituents at the C-5 or N-3, or both positions. Since the inception of Epralestat into the market in 1992, the exploration of rhodanine-3-acetic acids has led to the development of novel leads against different biological targets such as MRSA, HHV-6, Mycobacterial tuberculosis, dengue, etc. In the current pandemic era, some rhodanine compounds have been explored against SARS-CoV-2. In recent years, rhodanine and its derivatives have witnessed significant progress in developing new drug leads as potential antimicrobial and antiviral agents. Different synthetic methodologies and recent developments in the medicinal chemistry of rhodanine derivatives, including biological activities, their mechanistic aspects, structure-activity relationships, and in silico findings, have been compiled in the present review. This article will benefit the scientific community and offer perspectives on how these scaffolds as privileged structures might be exploited in the future for rational design and discovery of rhodanine-based bio-active molecules.

SAR analysis of heterocyclic compounds with monocyclic and bicyclic structures as antifungal agents

Infections caused by eukaryotic organisms, such as fungi, are generally more difficult to treat than bacterial infections. With the widespread use of antifungal drugs in humans and plants, resistance and toxicity have emerged. Therefore, it is desirable to develop new antifungal drugs with low toxicity that are not susceptible to the development of resistance. This review presents a summary of the past 2017 to 2021 years of research on heterocyclic compounds as antifungal agents for use in humans and plants, focusing on the structure-activity relationships (SAR) of these compounds. This review may provide ideas and data for designing and developing new antifungal drugs with fewer side effects compared with currently available drugs.