Parul Chauhan

Transition-Metal-Free C-3 Arylation of Quinoline-4-ones with Arylhydrazines.

A transition-metal-free C-3-arylation of quinolin-4-ones in the presence of base has been achieved by using arylhydrazines as aryl radical source and air as oxidant. The reaction proceeds smoothly at room temperature and does not require any prefunctionalization and N-protection of quinoline-4-ones. The utility of this methodology is further demonstrated in synthesis of quinoline-quinolone hybrid as well as 6-aryl-benzofuro[3,2-c]quinoline scaffold.

Regioselective α-arylation of coumarins and 2-pyridones with phenylhydrazines under transition-metal-free conditions

A facile regioselective metal-free direct α-arylation of coumarins and 2-pyridones is achieved by the reaction of coumarins and 2-pyridones with phenylhydrazine in good yields. The reaction proceeds at room temperature under mild conditions using inexpensive reagents and without the need for step intensive activating groups. The methodology is operationally simple, practically viable and also allows the coupling of similar nitrogen heterocycle aza-coumarins without prerequisite N-protection.

A withanolide coagulin-L inhibits adipogenesis modulating Wnt/β-catenin pathway and cell cycle in mitotic clonal expansion

Obesity is a result of adipocyte hypertrophy followed by hyperplasia. It is a risk factor for several metabolic disorders such as dyslipidemia, type-2 diabetes, hypertension, and cardiovascular diseases. Coagulanolides, particularly coagulin-L isolated from W. coagulan has earlier been reported for anti-hyperglycemic activity. In this study, we investigated the effect of coagulin-L on in vitro models of adipocyte differentiation including 3T3-L1 pre-adipocyte, mouse stromal mesenchymal C3H10T1/2 cells and bone marrow derived human mesenchymal stem cells (hMSCs). Our results showed that, coagulin-L reduces the expressions of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), the major transcription factors orchestrating adipocyte differentiation. Detailed analysis further proved that early exposure of coagulin-L is sufficient to cause significant inhibition during adipogenesis. Coagulin-L inhibited mitotic clonal expansion (MCE) by delayed entry in G1 to S phase transition and S-phase arrest. This MCE blockade was caused apparently by decreased phosphorylation of C/EBPβ, modulation in expression of cell cycle regulatory proteins, and upregulation of Wnt/β-catenin pathway, the early stage regulatory proteins of adipogenic induction. Taken together all evidences, a known anti-hyperglycemic agent coagulin-L has shown potential to inhibit adipogenesis significantly, which can be therapeutically exploited for treatment of obesity and metabolic syndrome.

Palladium and copper-catalyzed ligand-free coupling of phenylhydrazines in water

An efficient protocol has been developed for the synthesis of biaryls via Pd/Cu catalyzed coupling of phenylhydrazines in water. Homo and cross couplings were successfully achieved in a ligand-free catalytic system, at room temperature with water as sole reaction medium.

A mild CuBr–NMO oxidative system for the coupling of anilines leading to aromatic azo compounds

An efficient, mild and cost-effective method has been developed utilizing CuBr with N-methylmorpholine N-oxide (NMO/NMMO) for the oxidative coupling of anilines to access symmetrical and unsymmetrical azo compounds in high yield. The reactivity was found to be governed by electronic and steric factors of anilines.

Coagulin-L ameliorates TLR4 induced oxidative damage and immune response by regulating mitochondria and NOX-derived ROS.

Withanolides possess diverse biological and pharmacological activity but their immunomodulatory function is less realized. Hence, coagulin-L, a withanolide isolated from Withania coagulans Dunal has been studied for such an effect in human and murine cells, and mice model. Coagulin-L (1, 3, 10μM) exhibited immunomodulatory effect by suppressing TLR4 induced immune mediators such as cytokines (GMCSF, IFNα, IFNγ, IL-1α, IL-1Rα, IL-1β, IL-2, IL-2R, IL-4, IL-5, IL-6, IL-7, IL-10, IL-12 (p40/p70), IL-13, IL-15, IL-17), chemokines (IL-8/CXCL8, MIG/CXCL9, IP-10/CXCL10, KC, MCP-1/CCL2, MIP-1α/CCL3, MIP-1β/CCL4, RANTES/CCL5, eotaxin/CCL11), growth factors (FGF-basic, VEGF), nitric oxide and intracellular superoxide. Mechanistically, coagulin-L abrogated LPS induced total and mitochondrial ROS generation, NOX2, NOX4 mRNA expression, IRAK and MAPK (p38, JNK, ERK) activation. Coagulin-L also attenuated IκBα degradation, which prevented NFκB downstream iNOS expression and pro-inflammatory cytokine release. Furthermore, coagulin-L (10, 25, 50mg/kg, p.o.), undermined the LPS (10mg/kg, i.p.) induced endotoxemia response in mice as evinced from diminished cytokine release, nitric oxide, aortic p38 MAPK activation and endothelial tissue impairment besides suppressing NOX2 and NOX4 expression in liver and aorta. Moreover, coagulin-L also alleviated the ROS mediated oxidative damage which was assessed through protein carbonyl, lipid hydroperoxide, 8-isoprostane and 8-hydroxy-2-deoxyguanosine quantification. To extend, coagulin-L also suppressed carrageenan-induced paw edema and thioglycollate-induced peritonitis in mice. Therefore, coagulin-L can be of therapeutic importance in pathological conditions induced by oxidative damage.

p-TsOH-promoted synthesis of (E)-6-phenyl-7-styryl-5,6-dihydrodibenzo[b,h][1,6]naphthyridines via cascade intramolecular aza-Michael addition/Friedlander condensation of 2′-aminochalcones in a SDS/H2O system

Bronsted acid-promoted cascade synthesis of novel (E)-6-phenyl-7-styryl-5,6-dihydrodibenzo[b,h][1,6]naphthyridines has been achieved via homodimerization of 2′-aminochalcones by employing sodium dodecylsulphate (SDS) as a surfactant in water. Besides water as an environmentally benign reaction medium, the reaction proceeds smoothly with high atom-economy under a sequential one-pot protocol.

Eosin Y–Yb(OTf)3 catalyzed visible light mediated electrocyclization/indole ring opening towards the synthesis of heterobiaryl-pyrazolo[3,4-b]pyridines

A catalytic combination of eosin Y–Yb(OTf)3 has been developed to catalyse the visible light mediated synthesis of indole substituted heterobiaryl-pyrazolo[3,4-b]pyridines in good yields under mild reaction conditions. The current reaction proceeds through a dual, Lewis acid and oxidative photo-catalysis to afford the corresponding product at room temperature via electrocyclization and indole ring opening.