Activation of lysosomal mediated cell death in the course of autophagy by mTORC1 inhibitor.

Lysosomal biogenesis plays a vital role in cell fate. Under certain conditions, excessive lysosomal biogenesis leads to susceptibility for lysosomal membrane permeabilization resulting in various pathological conditions including cell death. In cancer cells apoptosis machinery becomes dysregulated during the course of treatment, thus allows cancer cells to escape apoptosis. So it is therefore imperative to identify cytotoxic agents that exploit non-apoptotic mechanisms of cell death. Our study showed that pancreatic cancer cells treated with SDS-203 triggered an incomplete autophagic response and a nuclear translocation of transcriptional factor TFEB. This resulted in abundant biosynthesis and accumulation of autophagosomes and lysosomes into the cells leading to their death. It was observed that the silencing of autophagy genes didn't alter the cell fate, whereas siRNA-mediated silencing of TFEB subdued SDS-203 mediated lysosomal biogenesis and associated cell death. Further mouse tumors treated with SDS-203 showed a significant reduction in tumor burden and increased expression of lysosomal markers. Taken together this study demonstrates that SDS-203 treatment triggers non-apoptotic cell death in pancreatic cancer cells through a mechanism of lysosome over accumulation.

Oxone-DMSO Triggered Methylene Insertion and C(sp2)-C(sp3)-H-C(sp2) Bond Formation to Access Functional Bis-Heterocycles.

Metal-free insertion of a methylene group was achieved for the construction of a new C(sp2)-C(sp3)-H-C(sp2) bond in order to prepare novel bis-heterocyclic scaffolds. The complete mechanistic investigations included experimental study and DFT calculations, and various symmetric and unsymmetric bis-pyrazoles as well as other pyrazole-based bis-heterocyclic molecules were prepared in moderate to high yields. Further modification of the bridged methylene group in the unsymmetric pyrazoles generated a chiral center to extend the scope of this method.

Direct N-heterocyclization of hydrazines to access styrylated pyrazoles: synthesis of 1,3,5-trisubstituted pyrazoles and dihydropyrazoles.

A microwave-assisted method has been developed for the synthesis of tri-substituted pyrazoles via direct N-heterocyclization of hydrazines with metal-acetylacetonate and -dibenzylideneacetonate without using any base or additives. Most importantly, the synthesis of 1-aryl-5-phenyl-3-styryl-1H-pyrazoles was achieved in a single step using hydrochloride salt of various phenylhydrazines and this is the first report for direct construction of these molecules. The reaction medium and microwave conditions play a critical role for their selective product formation during the reaction. The present reaction explored the usage of metal-diketonic complexes as reaction substrates providing acetylacetone and dibenzylideneacetone moieties to directly participate in cyclization with hydrazines to form the corresponding pyrazoles in excellent yields. The present protocol introduces the important N-heterocyclic moieties in the final structures, giving the reaction great applications from a medicinal chemistry perspective, particularly in the late stage modification strategies in drug discovery.

4-(N-Phenyl-N'-substituted benzenesulfonyl)-6-(4-hydroxyphenyl)quinolines as inhibitors of mammalian target of rapamycin.

A series of 4-(N-phenyl-N'-substituted benzenesulfonyl)-6-(4-hydroxyphenyl)quinolines was designed, synthesized and evaluated for their biological potential as anticancer agents by screening the molecules against panel of five human cancer cell lines viz. HL-60, MiaPaCa-2, HCT116, PC-3 and HEP-G2. The series has shown good mTOR inhibitory activity at 0.5 µM concentration. The representative compound 7h was found to be most active with the IC50 of 613 nM against mTOR. In supportive evidence, the western blotting experiment revealed that compound 7h is more potent in inhibiting p-mTOR (S2448) activity in 2-4h at 5 and 10 µM concentrations and was selective and specific towards mTORC1 versus mTORC2. Towards understanding the mechanistic aspects we studied cell cycle analysis, mitochondrial membrane potential loss in MiaPaca-2 cells for compound 7h. The docking study for this series was performed to understand the binding mode of the compounds and its consequent effect in biological activity, the initial interaction studies were found to be useful in design of molecules, where compound 7h has shown additional H-bond interaction with Lys2171 apart from Val2240 and also a small hydrophobic cleft was observed with Leu2185, Met2345 and Ile2356.

DMSO/I2 mediated C-C bond cleavage of α-ketoaldehydes followed by C-O bond formation: a metal-free approach for one-pot esterification.

A novel and efficient I2/DMSO mediated metal-free strategy is presented for the direct C-C bond cleavage of aryl-/heteroaryl- or aliphatic α-ketoaldehydes by C2-decarbonylation and C1-carbonyl oxidation to give the corresponding carboxylic acids followed by esterification in one pot, offering excellent yields in both the steps. Here, DMSO acts as the oxygen source/oxidant and this reaction works very well under both conventional heating and microwave irradiation. This is a very simple and convenient protocol.

A Novel Quinoline Based Second-generation mTOR Inhibitor that Induces Apoptosis and Disrupts PI3K-Akt-mTOR Signaling in Human Leukemia HL-60 Cells.

Deregulation of the PI3K-Akt-mTOR pathway is unanimously pragmatic in a number of tumors. This pathway pedals proliferation, survival, translation, and coupled with tumor-associated endurance. Current efforts focus on the discovery and development of novel inhibitors of this pathway. We have discovered 6-(4-phenoxyphenyl)-N-phenylquinolin-4-amine [PQQ] as a potent mTOR inhibitor with IC50 value of 64nM in a cell-based and cell-free mTOR assay. Mechanistically, PQQ was found to be a strong PI3K-Akt-mTOR-p70S6K cascade inhibitor in Human promyelocytic leukemia HL-60 cells. Moreover, it was found to be dual mTORC1 and mTORC2 inhibitor that inhibit the entire mTOR kinase-dependent functions and feedback commencement of PI3K/Akt pathway. PQQ simultaneously induces apoptosis via mitochondrial dependant pathway, which was confirmed through a battery of the assays, e.g. cellular and nuclear microscopy, annexin-V assay, cell cycle analysis and loss of mitochondrial membrane potential. In summary, PQQ discovered as a novel second-generation mTOR inhibitor with significant cytotoxic and apoptotic potentials. Thus, it might be a significant lead structure for the development of mTOR-targeted based anti-cancer therapeutics.

C-H oxygenation and N-trifluoroacylation of arylamines under metal-free conditions: a convenient approach to 2-aminophenols and N-trifluoroacyl-ortho-aminophenols.

Direct ortho-hydroxylation through C-H oxygenation and N-trifluoroacylation of anilines was achieved in a single step under metal-free conditions by using a combination of TFA and oxone. The method allowed the formation of functionalised amino phenolic compounds such as ortho-hydroxy-N-trifluoroacetanilides in good yields with broad substrate scope.