Targeting NLRP3 signaling by a novel-designed sulfonylurea compound for inhibition of microglial inflammation.

The nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome plays an important role in microglia-mediated inflammation. Dysregulation of NLRP3 signaling results in microglial activation and triggers inflammatory responses contributing to the development of neurological disorders including ischemic stroke, schizophrenia, Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). Inhibition of the NLRP3-linked inflammatory pathways reduces microglia-induced inflammation and is considered as a promising therapeutic approach for neuro-inflammatory diseases. In the present study, we report the development of AMS-17, a rationally-designed tertiary sulfonylurea compound for inhibition of inflammation in microglia. AMS-17 inhibited expression of the NLRP3, and its downstream components and cytokines such as caspase-1, tumor necrosis factor-α (TNF-α), IL-1ß and inducible nitric oxide synthase (iNOS). It also suppressed lipopolysaccharide (LPS)-induced N9 microglial cell phagocytosis in vitro and activation of the microglia in mouse brain in vivo. Together, these results provide promising evidences for the inhibitory effects of AMS-17 in inflammation. This proof-of-concept study provides a new chemical scaffold, designed with the aid of pharmacophore modeling, with NLRP3 inhibitory activity which can be further developed for the treatment of inflammation-associated neurological disorders.

Epigenetic modulation and apoptotic induction by a novel imidazo-benzamide derivative in human lung adenocarcinoma cells.

PURPOSE: Lung cancer is the most commonly diagnosed and leading cause of cancer death worldwide. Imidazo-benzamides are considered to be good anti-cancer agents. The present study was aimed to investigate the cytotoxicity of a novel imidazo-benzamide derivative N-(2-(3-(tert-butyl)ureido)ethyl)-4-(1H-imidazol-1-yl)benzamide (TBUEIB) in lung cancer cell line A549. METHODS: The antiproliferative activity of TBUEIB was investigated using MTT, LDH and trypan blue assay. The apoptotic potential was investigated using various staining techniques and further confirmed by DNA fragmentation assay and western blotting. RESULTS: TBUEIB inhibited fifty precent A549 cells at a dose of 106 µM. The novel compound was found to exert a modulatory effect on apoptotic marker caspase-3 as well as epigenetic regulatory proteins like DNA Methyltransferase 1 (DNMT1). In silico studies with the compound and other epigenetic proteins such as Histone deacetylase (HDAC) and ubiquitin-like with PHD (plant homeodomain) and RING (Really Interesting New Gene) finger domains 1(UHRF1) showed good modulatory effects. CONCLUSION: The overall results obtained in the study conclude that the novel compound TBUEIB has potential anti-cancer activities, mainly by targeting the expression of DNMT1 enzyme, which may have re-activated the major tumor suppressor genes involved in the cell cycle, leading to the apoptosis of the cancer cells. The results also indicate that the compound has more than one target in the epigenetic pathway implying that the compound may be a potential multi-target compound.

Pyrimidine-2,4-dione targets STAT3 signaling pathway to induce cytotoxicity in hepatocellular carcinoma cells.

Signal transducer and activator of transcription 3 (STAT3) is a tumorigenic transcription factor that is persistently activated in various human cancers including hepatocellular carcinoma (HCC). Therefore, STAT3 is considered as a prominent target to counteract the uncontrolled proliferation of cancer cells. In the present report, pyrimidine-2,4-diones (N-methyluracil derivatives) (MNK1-MNK14) were synthesized in an ionic liquid (BMIm PF6) medium employing a ligand-free Suzuki-Miyaura cross-coupling process. Among the 14 derivatives, compound MNK8 showed good cytotoxicity towards both the tested cell lines and did not display a toxic effect against normal hepatocytes (LO2). MNK8 significantly increased the Sub-G1 cell count in both cell lines and the cytotoxic effect of MNK8 was found to be mediated through the suppression of constitutive phosphorylation of STAT3Y705. It also decreased the DNA interaction ability of nuclear STAT3 in HCC cells. MNK8 downregulated the levels of apoptosis-related proteins (such as Bcl-2, cyclin D1, survivin) and increased cleaved caspase-3 inferring the apoptogenic effect of MNK8. It also reduced the CXCL12-triggered cell migration and invasion in in vitro assay systems. Overall, MNK8 has been demonstrated as a new inhibitor of STAT3 signaling cascade in HCC cells.

Inhibition of dengue virus by curcuminoids.

The dengue virus is considered to be a globally important human pathogen prevalent in tropical and subtropical regions of the world. According to a recent estimate, the disease burden due to DENV infections is ∼390 million infections per year globally in ∼100 countries including the southern US, Puerto Rico and Hawaii, resulting in nearly ∼25,000 deaths mostly among children. Despite the significant morbidity and mortality that results from DENV infections, there is currently no effective chemotherapeutic treatment for DENV infections. We identified curcumin as an inhibitor of DENV2 NS2B/NS3protease in a previous high-throughput screening (HTS) campaign. We synthesized four analogues of curcumin (curcuminoids) and tested the in vitro protease inhibition activity and inhibition of replication by cell-based assays. The results revealed that curcumin is a weak inhibitor of the viral protease. However, the analogues exhibited more potent inhibition of DENV infectivity in plaque assays suggesting that the cellular pathway(s) required for viral replication and/or assembly are targeted by these compounds. Further analysis shows that inhibition of genes involved in lipid biosynthesis, and of actin polymerization by curcuminoids, are likely to be involved as their mode of action in DENV2-infected cells. Three of the curcumin derivatives possess good selectivity indices (SI) (>10) when compared to the parent curcumin.

Novel tacrine derivatives exhibiting improved acetylcholinesterase inhibition: Design, synthesis and biological evaluation.

A novel series of twenty four tacrine derivatives were designed and synthesised. Among these, thirteen were taken for the acetylcholinesterase (AChE) inhibition studies. Three compounds such as 4c, 6c and 6f were found to possess significant AChE inhibitory properties with IC50 values 12.97 ± 0.47 nM, 5.17 ± 0.24 nM and 7.14 ± 0.78 nM respectively. In silico docking studies revealed that these compounds can bind strongly in the active site of the enzyme and prevent enzyme-substrate interactions. On binding, the substituted groups were oriented either towards the peripheral anionic site (PAS) (Pocket A) or towards a hydrophobic cavity (pocket B) located near the active site. The cytotoxicity and hepatotoxicity of the compounds were tested using HEK-293 and HepG2 cell lines respectively. The compound 4c did not show any significant decrease in the cell viability even at a concentration of 300 µM indicating that its cytotoxicity and hepatotoxicity are significantly lesser compared to tacrine, due to the chemical modification. Based on the available results, it can be suggested that the compound 4c might be a potential drug lead compound with AChE inhibitory activity. However, further pharmacokinetic studies are necessary to comment on the efficacy of the compound as a drug for AD.

Design, synthesis and structure--activity relationship (SAR) studies of imidazo[4,5-b]pyridine derived purine isosteres and their potential as cytotoxic agents.

Drug resistance to chemotherapeutic agents paved the way to develop novel synthetic molecules which are active on MDR cancer cell lines. Regio-isomeric imidazo[4,5-b]pyridine analogues were synthesized and evaluated for their cytotoxic activity against a range of cancer cell lines. The structure-activity relationship (SAR) studies of the imidazopyridine analogues are also described. Analogue 6b displayed strong cytotoxicity and good microsomal stability.