Exploring the newer oxadiazoles as real inhibitors of human SIRT2 in hepatocellular cancer cells

A novel series of indazole tethered oxadiazoles (OTDs) derivatives were synthesized, characterized and screened for their anti-proliferative activity against hepatocellular carcinoma (HCC) cells. OTDs structure was further confirmed by Single-crystal X-ray diffraction studies. Among the tested OTDs, compound 2-(4-methoxyphenyl)-5-(1-methyl-1H-indazol-3-yl)-1,3,4-oxadiazole was found to inhibit the catalytical activity of SIRT2 and brings about apoptosis as shown by western blot analysis and flow cytometry data. Also, the tested OTDs were found to interact with the active site of human SIRT2 in silico but not with the cavity of co-crystal ligand 5-(3- hydroxypropyl)-3-(4-chlorophenyl)-1,2,4-oxadiazole, which indicate that these OTDs has potential in the development of SIRT2 inhibitors in liver cancer models.     

The impact of binding site waters on the activity/selectivity trade-off of Janus kinase 2 (JAK2) inhibitors

Structure based optimization of B39, an indazole-based low micromolar JAK2 virtual screening hit is reported. Analysing the effect of certain modifications on the activity and selectivity of the analogues suggested that these parameters are influenced by water molecules available in the binding site. Simulation of water networks in combination with docking enabled us to identify the key waters and to optimize our primary hit into a low nanomolar JAK2 lead with promising selectivity over JAK1.     

Discovery of 2-(1H-indazol-1-yl)-thiazole derivatives as selective EP1 receptor antagonists for treatment of overactive bladder by core structure replacement

We have designed a series of potent EP₁ receptor antagonists. These antagonists are a series of 2-(1H-indazol-1-yl)-thiazoles in which the core structure was replaced with pyrazole-phenyl groups. In preliminary conscious rat cystometry experiments, two representative candidates, 2 and 22, increased bladder capacity. In particular, the increase using 22 was approximately 2-fold that of the baseline. More detailed profiling of this compound and further optimization of this series promises to provide a novel class of drug for treating overactive bladder (OAB).     

Amine-free melanin-concentrating hormone receptor 1 antagonists: Novel non-basic 1-(2H-indazole-5-yl)pyridin-2(1H)-one derivatives and mitigation of mutagenicity in Ames test

To develop non-basic melanin-concentrating hormone receptor 1 (MCHR1) antagonists with a high probability of target selectivity and therapeutic window, we explored neutral bicyclic motifs that could replace the previously reported imidazo[1,2-a]pyridine or 1H-benzimidazole motif. The results indicated that the binding affinity of a chemically neutral 2H-indazole derivative 8a with MCHR1 (hMCHR1: IC₅₀ = 35 nM) was comparable to that of the imidazopyridine and benzimidazole derivatives (1 and 2, respectively) reported so far. However, 8a was positive in the Ames test using TA1537 in S9− condition. Based on a putative intercalation of 8a with DNA, we introduced a sterically-hindering cyclopropyl group on the indazole ring to decrease planarity, which led to the discovery of 1-(2-cyclopropyl-3-methyl-2H-indazol-5-yl)-4-{[5-(trifluoromethyl)thiophen-3-yl]methoxy}pyridin-2(1H)-one 8l without mutagenicity in TA1537. Compound 8l exerted significant antiobesity effects in diet-induced obese F344 rats and exhibited promising safety profile.     

Synthesis and SAR studies of 3,6-disubstituted indazole derivatives as potent hepcidin production inhibitors

Hepcidin has emerged as the central regulatory molecule of systemic iron homeostasis. Inhibition of hepcidin could be a strategy favorable to treating anemia of chronic disease (ACD). We report herein the synthesis and structure-activity relationships (SARs) of a series of indazole compounds as hepcidin production inhibitors. The optimization study of compound 1 led to a potent hepcidin production inhibitor 45, which showed serum hepcidin lowering effects in a mouse IL-6 induced acute inflammatory model.     

A series of novel indazole derivatives of Sirt 1 activator as osteogenic regulators

A series of indazole derivatives were identified as Sirt 1 activators though high-throughput screening. Optimization of each substituent on the indazole ring led to the identification of compound 13. Compound 13 appeared to give the best Sirt 1 activity of the compounds tested and also showed osteogenesis activity in a cell assay. Sirt 1 activators are therefore potential candidates for the treatment of osteoporosis.     

Optimization of a pyrazole hit from FBDD into a novel series of indazoles as ketohexokinase inhibitors

A series of indazoles have been discovered as KHK inhibitors from a pyrazole hit identified through fragment-based drug discovery (FBDD). The optimization process guided by both X-ray crystallography and solution activity resulted in lead-like compounds with good pharmaceutical properties.     

Synthesis and evaluation of novel 17-indazole androstene derivatives designed as CYP17 inhibitors

A series of novel 1H- and 2H-indazole derivatives of the commercially available dehydroepiandrosterone acetate have been synthesized and tested for inhibition of human cytochrome 17alpha-hydroxylase-C(17,20)-lyase (CYP17), androgen receptor (AR) binding affinity, and cytotoxic potential against three prostate cancer (PC) cell lines.     

Design, synthesis and SAR of indazole and benzoisoxazole containing 4-azetidinyl-1-aryl-cyclohexanes as CCR2 antagonists

A novel series of 4-azetidinyl-1-aryl-cyclohexanes containing indazole or benzoisoxazole moiety have been identified as potent CCR2 antagonists with high selectivity versus hERG.     

Novel serotonin type 3 receptor partial agonists for the potential treatment of irritable bowel syndrome

Serotonin type 3 (5-HT₃) receptor partial agonists are being targeted as potential new drugs for the treatment of irritable bowel syndrome (IBS). Two new chemical series bearing indazole and indole cores have exhibited nanomolar binding affinity for the h5-HT₃A receptor. A range of partial agonist activities in HEK cells heterologously expressing the h5-HT₃A receptor were measured for the indazole series. Excellent 5-HT₃ receptor selectivity, favorable in vitro metabolic stability and CYP inhibition properties, and good oral in vivo potency in the murine von Bezold-Jarisch reflex model is exemplified thereby indicating the series to have potential utility as improved IBS agents.