Mohd. Kamil Hussain

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.

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.

The anti-proliferative effect of 2-[piperidinoethoxyphenyl]-3-[4-hydroxyphenyl]-2H-benzo(b) pyran is potentiated via induction of estrogen receptor beta and p21 in human endometrial adenocarcinoma cells

In an effort to develop novel therapeutic agents for endometrial cancer, benzopyran derivatives synthesized at our institute display significant inhibitory activity on cellular growth in uterine cancer cells. The current study was undertaken to demonstrate and explore the estrogen receptor (ER) subtype mediated mechanism of action of benzopyran derivative 2-[piperidinoethoxyphenyl]-3-[4-hydroxyphenyl]-2H-benzo(b) pyran (K-1) in human endometrial cancer cells. K-1 competitively inhibited the estradiol binding to human ERα and ERβ and showed growth inhibitory activity in human endometrial Ishikawa, HEC1B and primary endometrial adenocarcinoma cells. Transient transactivation assays carried out in COS-1 cells have demonstrated the diminished ERα-ERE mediated- and induced the ERβ-ERE mediated-transactivation triggered by compound. It also induced ER-mediated transactivation of the cyclin-dependent kinase inhibitor (CDKI) p21(WAF-1) in both COS-1 cells and in Ishikawa cells. ERβ inducing effects of compound were blocked by ICI182,780. In endometrial adenocarcinoma cells, it induced ERβ and p21 expression significantly whereas the expression of fos, jun and ERα were significantly reduced. In addition, compound promoted ERα-β heterodimerization as observed in Ishikawa cells. These results demonstrate that the benzopyran compound suppressed the cellular growth via ERβ agonism, induction of p21 and via promoting the ERα-β heterodimerization, in addition to its antagonistic effects exerted on ERα, in human endometrial cancer cells. The study suggests that the dual action of benzopyran molecule may be of significant therapeutic value in ERα/β-positive cases of endometrial cancer.

A Novel Benzocoumarin-Stilbene Hybrid as a DNA ligase i inhibitor with in vitro and in vivo anti-tumor activity in breast cancer models

Existing cancer therapies are often associated with drug resistance and toxicity, which results in poor prognosis and recurrence of cancer. This necessitates the identification and development of novel therapeutics against existing as well as novel cellular targets. In this study, a novel class of Benzocoumarin-Stilbene hybrid molecules were synthesized and evaluated for their antiproliferative activity against various cancer cell lines followed by in vivo antitumor activity in a mouse model of cancer. The most promising molecule among the series, i.e. compound (E)-4-(3,5-dimethoxystyryl)-2H-benzo[h]chromen-2-one (19) showed maximum antiproliferative activity in breast cancer cell lines (MDA-MB-231 and 4T1) and decreased the tumor size in the in-vivo 4T1 cell-induced orthotopic syngeneic mouse breast cancer model. The mechanistic studies of compound 19 by various biochemical, cell biology and biophysical approaches suggest that the compound binds to and inhibits the human DNA ligase I enzyme activity that might be the cause for significant reduction in tumor growth and may constitute a promising next-generation therapy against breast cancers.

Identification of a novel human DNA ligase I inhibitor that promotes cellular apoptosis in DLD-1 cells: an in silico and in vitro mechanistic study

The processes of DNA replication and repair are accomplished by the concerted action of several proteins. Among them human DNA ligases play an important role during the last step of almost all DNA replication and repair processes, where they seal the nicks between DNA strands. In humans, three kinds of DNA ligases (human DNA ligase I, III, IV) are found. DNA ligase I (hLigI) is involved in both DNA replication as well as in DNA repair pathways and is reported to be over-expressed in rapidly dividing cells, including cancer cells. For this reason, in this study we have targeted hLigI for studying its response as a novel anticancer target. We have screened for ligase I inhibitors from our in-house small molecule library by a previously validated pharmacophore based virtual screening method and found a novel hLigI inhibitor. This compound (S-097/98) demonstrated antiproliferative activities specifically in DLD-1 (colon), MDA-MB-231 (triple negative breast) and HepG2 (liver) cancer cell lines at low micromolar concentrations of 6–7 μM. Mechanistic studies show that the compound can directly interacts with the hLigI protein and inhibits ligation of both the purified protein in vitro, as well as in cell lysate of DLD-1 cells treated with the inhibitor. The compound also arrests cell cycle progression at the G2/M phase and increases the nuclear size of DLD-1 cancer cells, thereby demonstrating its antiproliferative activity. Finally, the compound promotes cellular apoptosis in DLD-1 cells.

The regulation of Hh/Gli1 signaling cascade involves Gsk3β- mediated mechanism in estrogen-derived endometrial hyperplasia

The present study was undertaken to explore the functional involvement of Hh signaling and its regulatory mechanism in endometrial hyperplasia. Differential expression of Hh signaling molecules i.e., Ihh, Shh, Gli1 or Gsk3β was observed in endometrial hyperplasial (EH) cells as compared to normal endometrial cells. Estradiol induced the expression of Hh signaling molecules and attenuated the expression of Gsk3β whereas anti-estrogen (K1) or progestin (MPA) suppressed these effects in EH cells. Cyclopamine treatment or Gli1 siRNA knockdown suppressed the growth of EH cells and reduced the expression of proliferative markers. Estradiol also induced the nuclear translocation of Gli1 which was suppressed by both MPA and K1 in EH cells. While exploring non-canonical mechanism, LY-294002 (Gsk3β activator) caused a decrease in Gli1 expression indicating the involvement of Gsk3β in Gli1 regulation. Further, Gsk3β silencing promoted the expression and nuclear translocation of Gli1 demonstrating that Gsk3β serves as a negative kinase regulator of Gli1 in EH cells. Similar attenuation of Hh signaling molecules was observed in rats with uterine hyperplasia undergoing anti-estrogen treatment. The study suggested that Hh/Gli1 cascade (canonical pathway) as well as Gsk3β-Gli1 crosstalk (non-canonical pathway) play crucial role in estrogen-dependent cell proliferation in endometrial hyperplasia.

Elucidation of pharmacokinetics of novel DNA ligase I inhibitor, S012-1332 in rats: Integration of in vitro and in vivo findings

&NA; S012‐1332 is the first DNA ligase I inhibitor that demonstrated in vivo anti‐breast cancer activity. The present study aimed to assess the in vivo pharmacokinetics of S012‐1332 in rats and interpret them with in vitro findings. A sensitive and selective liquid chromatography‐tandem mass spectrometry bioanalytical method was developed and validated to determine S012‐1332. Following oral administration, the absolute bioavailability was 7.04%. The absorption was prolonged which can be explained by low solubility in simulated gastric fluid and several folds higher solubility in simulated intestinal fluid. The effective permeability across the intestinal membrane in in situ single pass perfusion study for S012‐1332 was 5.58 ± 1.83 * 10−5 cm/sec compared to 5.99 ± 0.65 * 10−5 cm/sec for carbamazepine, with no significant difference, indicating S012‐1332 has high permeability. It was rapidly partitioning into plasma in blood, where it was stable. Plasma protein binding was moderate which may have attributed to the rapid distribution out of the vascular compartment. The pharmacokinetics of S012‐1332 was characterized by extensive clearance as seen with rat liver and intestinal microsomes. In vitro results elucidate the in vivo pharmacokinetic data. These findings provide crucial information for further development of S012‐1332 as anti‐breast cancer agent. Graphical abstract Figure. No caption available. HighlightsLC‐MS/MS method has been developed and validated for the first time for S012‐1332.Absolute oral bioavailability of S012‐1332 was 7.04% in rats.In vitro findings show low solubility, high metabolism, moderate protein binding.Stable in plasma and biorelevant media and highly permeable.

Dithiolethiones: a privileged pharmacophore for anticancer therapy and chemoprevention

Dithiolethiones are five-membered sulfur-containing cyclic scaffolds that exhibit antioxidative, anti-inflammatory, antithrombic and chemotherapeutic activities. Dithiolethiones display the chemopreventive and cytoprotective effects by activating the antioxidant response element and mounting the transcription of cytoprotective phase II enzymatic machinery. In addition, several classes of dithiolethiones efficiently modulate the activities of proteins that play crucial roles in normal and cancer cells, including glutathione S-transferase, cyclooxygenases and master regulator NF-κB. The present paper summarizes synthetic aspects, pharmacological potentials and biological attributes of dithiolethiones and its derivatives. Additionally, this review concludes with a discussion on how the current state-of-the-art technologies may help in defining a structure-activity relationship of dithiolethiones, thereby facilitating the design and synthesis of potent drug candidates.