Kanchan Hajela

Synthesis and biological evaluation of 3,4,6-triaryl-2-pyranones as a potential new class of anti-breast cancer agents.

A series of 3,4,6-triaryl-2-pyranones, new class of anti-breast cancer agents, have been synthesized as a structural variants of cyclic triphenylethylenes by replacing the fused benzene ring with pendant phenyl ring to mimic the phenolic A ring of estradiol. Nine of these newly synthesized pyranones exhibited significant anti-proliferative activity in both ER+ve and ER-ve breast cancer cell lines. Four active non-cytotoxic compounds 5c, 5d, 5g and 5h showed specific and selective cytotoxicity and two compounds 5d and 5h induced significant DNA fragmentation in both MCF-7 and MDA-MB-231 cell lines. Based on RBA studies, the molecules probably act in an ER-independent mechanism. The involved pathway was observed as caspase-dependant apoptosis in MCF-7 cells. However, the particular caspases involved and the possible cellular target through which this series of compounds mediate cell death are not known.

NAD+-dependent DNA ligase (Rv3014c) from Mycobacterium tuberculosis: Novel structure-function relationship and identification of a specific inhibitor

Mycobacterium tuberculosis codes for an essential NAD+‐dependent DNA ligase (MtuLigA) which is a novel, validated, and attractive drug target. We created mutants of the enzyme by systematically deleting domains from the C‐terminal end of the enzyme to probe for their functional roles in the DNA nick joining reaction. Deletion of just the BRCT domain from MtuLigA resulted in total loss of activity in in vitro assays. However, the mutant could form an AMP‐ligase intermediate that suggests that the defects caused by deletion of the BRCT domain occur primarily at steps after enzyme adenylation. Furthermore, genetic complementation experiments using a LigA deficient E. coli strain demonstrates that the BRCT domain of MtuLigA is necessary for bacterial survival in contrast to E. coli and T. filiformis LigA, respectively. We also report the identification, through virtual screening, of a novel N‐substituted tetracyclic indole that competes with NAD+ and inhibits the enzyme with IC50 in the low μM range. It exhibits ∼15‐fold better affinity for MtuLigA compared to human DNA ligase I. In vivo assays using LigA deficient S. typhimurium and E. coli strains suggest that the observed antibacterial activity of the inhibitor arises from specific inhibition of LigA over ATP ligases in the bacteria. In silico ligand‐docking studies suggest that the exquisite specificity of the inhibitor arises on account of its mimicking the interactions of NAD+ with MtuLigA. An analysis of conserved water in the binding site of the enzyme suggests strategies for synthesis of improved inhibitors with better specificity and potency. Proteins 2007.

Design and synthesis of ERα/ERβ selective coumarin and chromene derivatives as potential anti-breast cancer and anti-osteoporotic agents

Several new coumarin and chromene prototype derivatives have been synthesised and evaluated for their ERα and ERβ selective activity. Coumarin prototype compounds 18 & 19 were found to be ERα selective and the most active, exhibiting potential antiproliferative activity against both ER +ve & ER −ve breast cancer cell lines. The surprise finding of the series, however, are the novel prototype III chromenes 45 & 46, with aroyl substitution at the 6th position. Both the compounds have shown potent antiproliferative activity against both the breast cancer cell lines, promote alkaline phosphatase activity, enhance osteoblast mineralization in vitro, significantly decrease ERE–ERα dependent transactivation and induce ERβ activity. This specific upregulation of ERβ isoform activity of compound 45 may be responsible for the antiosteoporotic activity at picomolar concentration. In addition, both the compounds were also devoid of any estrogenic activity, which correlates to their antiestrogenic behaviour in the two breast cancer cell lines. Assessment of selectivity using specific SiRNAs for ERα and ERβ revealed that most of the compounds showed ERα and ERβ-mediated action, except compound 28, which showed selectivity to ERα only. Computational docking analysis of active compounds 18 and 45 was conducted to correlate the interaction with the two receptors and it was found that the docked conformations of the coumarin prototype, compound 18 at ERα and ERβ active sites were more or less superimposable on each other. However, the unique orientation of the aminoalkoxy side chain of novel chromene (prototype III) compound 45 in the ERβ binding cavity may be responsible for its potential biological response.

Tandem C-2 Functionalization–Intramolecular Azide–Alkyne 1,3-Dipolar Cycloaddition Reaction: A Convenient Route to Highly Diversified 9H-Benzo[b]pyrrolo[1,2-g][1,2,3]triazolo[1,5-d][1,4]diazepines

An efficient diversity-oriented synthetic approach to annulated 9H-benzo[b]pyrrolo[1,2-g][1,2,3]triazolo[1,5-d][1,4]diazepines has been developed using a Sc(OTf)3-catalyzed two-component tandem C-2 functionalization-intramolecular azide-alkyne 1,3-dipolar cycloaddition reaction. The reaction shows high substrate tolerance and provides a library of fused heterocycles that may lead to novel biologically active compounds or drug lead molecules.

A highly efficient ultrasound-promoted synthesis of 2,3-disubstituted benzo[b]furans via intramolecular C–C bond formation in ionic liquid[bmim]BF4 at room temperature

An efficient ultrasound-promoted synthesis of 2,3-disubstituted benzo[b]furans in the ionic liquid [bmim]BF4 at room temperature is reported. 5-exo-dig carbanion–yne intramolecular cyclization is mediated using anhydrous K3PO4 as a mild, inexpensive base under atmospheric conditions giving the title benzo[b]furans in excellent yields. Ionic liquid [bmim]BF4 has been used both as a reaction medium, as well as a catalyst for the C–C bond formation.

Chemotherapeutic Potential of 2-[Piperidinoethoxyphenyl]-3-Phenyl-2H-Benzo(b)pyran in Estrogen Receptor- Negative Breast Cancer Cells: Action via Prevention of EGFR Activation and Combined Inhibition of PI-3-K/Akt/FOXO and MEK/Erk/AP-1 Pathways

Inhibition of epidermal growth factor receptor (EGFR) signaling is considered to be a promising treatment strategy for estrogen receptor (ER)-negative breast tumors. We have investigated here the anti-breast cancer properties of a novel anti-proliferative benzopyran compound namely, 2-[piperidinoethoxyphenyl]-3-phenyl-2H-benzo(b)pyran (CDRI-85/287) in ER- negative and EGFR- overexpressing breast cancer cells. The benzopyran compound selectively inhibited the EGF-induced growth of MDA-MB 231 cells and ER-negative primary breast cancer cell culture. The compound significantly reduced tumor growth in xenograft of MDA-MB 231 cells in nude mice. The compound displayed better binding affinity for EGFR than inhibitor AG1478 as demonstrated by molecular docking studies. CDRI-85/287 significantly inhibited the activation of EGFR and downstream effectors MEK/Erk and PI-3-K/Akt. Subsequent inhibition of AP-1 promoter activity resulted in decreased transcription activation and expression of c-fos and c-jun. Dephosphorylation of downstream effectors FOXO-3a and NF-κB led to increased expression of p27 and decreased expression of cyclin D1 which was responsible for decreased phosphorylation of Rb and prevented the transcription of E2F- dependent genes involved in cell cycle progression from G1/S phase. The compound induced apoptosis via mitochondrial pathway and it also inhibited EGF-induced invasion of MDA-MB 231 cells as evidenced by decreased activity of MMP-9 and expression of CTGF. These results indicate that benzopyran compound CDRI-85/287 could constitute a powerful new chemotherapeutic agent against ER-negative and EGFR over-expressing breast tumors.

A metal-free tandem approach to prepare structurally diverse N-heterocycles: synthesis of 1,2,4-oxadiazoles and pyrimidinones

A metal-free one-pot approach to the diversity oriented synthesis of N-heterocycles, 1,2,4-oxadiazoles and 2,6 disubstituted pyrimidin-4-ones is described via carboxamidation of amidines with aryl carboxylic acids and aryl propargylic acids. The reactions occur at room temperature forming N-acylamidines which undergo tandem nucleophilic addition–deamination–intramolecular cyclisation to give the corresponding heterocyclic compounds in good to excellent yields. This one pot approach has led to the successful synthesis of the drug lead molecule, ataluren, 3-(5-(2-fluorophenyl)-1,2,4-oxadiazol-3-yl) benzoic acid in two steps.

Synthesis of targeted dibenzo[b,f]thiepines and dibenzo[b,f]oxepines as potential lead molecules with promising anti-breast cancer activity

A targeted library of substituted dibenzo[b,f]thiepines and dibenzo[b,f]oxepines (prototypes I, II and III), and structurally analogous to tamoxifen have been synthesized as a new class of anti-breast cancer agents. All the prototype molecules exhibited potential antiproliferative activity against ER + ve and ER-ve breast cancer cell lines. Dibenzo[b,f]thiepine prototypes were found to be more active. Of all the compound tested, 14b exhibited potent in-vitro antiproliferative activity at 1.33 μM and 5 μM concentration in MCF-7 and MDA-MB-231 cell lines and was devoid of any cytotoxicity in normal HEK cells even at 50 μM. Cell cycle analysis showed that the compound 14b inhibited cell proliferation due to G0/G1 arrest in MCF-7 cells. Annexin-V FITC and PI staining experiments confirmed that the cell inhibition was primarily due to apoptosis and not by necrosis, which was also supported by LDH release assay experiment. Molecular docking studies showed better binding interaction of the new dibenzo[b,f]thiepine analogue 14b with the estrogen receptor (ER) as compared to 4-hydroxy-tamoxifen and this enhanced binding might be responsible for its estrogen antagonistic activity that induces cell cycle arrest, apoptosis and inhibition of breast cancer cells.

2,3-Diaryl-2H-1-benzopyran derivatives interfere with classical and non-classical estrogen receptor signaling pathways, inhibit Akt activation and induce apoptosis in human endometrial cancer cells.

OBJECTIVES The present study was undertaken to explore the mechanism of anti-proliferative action of benzopyran compound D1 (2-[piperidinoethoxyphenyl]-3-phenyl-2H-benzopyran) and its hydroxy-(D2) and methoxy-(D3) derivatives in Ishikawa and human primary endometrial adenocarcinoma cells. METHODS Transcriptional activation assays were performed using luciferase reporter system and cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The stage of cell cycle was determined by flow-cytometry and real time analysis of cyclinE1 and cdc2 genes. The apoptotic effects were measured by AnnexinV/PI staining and TUNEL. The expression of PCNA, cyclinD1, pAkt, XIAP, cleaved caspase-9, -3, PARP, Bax and Bcl2 were determined by immunoblotting. The caspase-3 activity and mitochondrial membrane potential were measured by colorimetric assay. RESULTS All three compounds inhibited E(2)-induced ERE- and AP-1-mediated transactivation and proliferation in endometrial adenocarcinoma cells dose-dependently. Compound D1 caused the arrest of cells in the G(2) phase while D2 and D3 caused arrest in G(1) phase of the cell cycle. All compounds interfered with Akt activation, decreased XIAP expression leading to an increased cleavage of caspase-9, -3, PARP, increased Bax/Bcl2 ratio and caspase-3 activity. CONCLUSION Findings suggest that benzopyran derivatives inhibit cellular proliferation via modulating ER-dependent classical and non-classical signaling mechanisms, interfere with Akt activation and induce apoptosis via intrinsic pathway in endometrial adenocarcinoma cells.

Resolution, molecular structure and biological activities of the D- and L-enantiomers of potent anti-implantation agent, DL-2-[4-(2-piperidinoethoxy)phenyl]-3-phenyl-2H-1-benzopyran.

Compound 1 (DL-2-[4-(2-piperidinoethoxy)phenyl]-3-phenyl-2H-1-benzopyran, CDRI 85/287) a potent anti-estrogen and anti-implantation agent has been successfully resolved into its pure D- and L-enantiomers. Biological studies showed L-enantiomer to be the active form, exhibiting a fivefold higher receptor affinity for the rat uterine cytosolic estrogen receptor, 100% contraceptive efficacy at 1.3 mg/kg dose in single day schedule and 89% inhibition of estradiol induced increase of uterine weight at its contraceptive dose. The absolute stereochemistry determined by X-ray crystallographic analysis showed that the L-enantiomer has 2R configuration at its asymmetric centre.