Synthesis of Novel Pyrazole-Oxindole Conjugates with Cytotoxicity in Human Cancer Cells via Apoptosis.

A novel series of pyrazole-oxindole conjugates were prepared and characterized as potential cytotoxic agents by FT-IR, NMR and HR-MS. The cytotoxic activity of these compounds was tested in the Jurkat acute T cell leukemia, CEM acute lymphoblastic leukemia, MCF10 A mammary epithelial and MDA-MB 231 triple negative breast cancer cell lines. Among the tested conjugates, 5-methyl-3-((3-(1-phenyl)-3-(p-tolyl)-1H-pyrazol-4-yl)methylene)indolin-2-one 6h emerged as the most cytotoxic with a CC50 of 4.36+/-0.2 µM against Jurkat cells. The mechanism of cell death induced by 6h was investigated through the Annexin V-FITC assay via flow cytometry. Reactive oxygen species (ROS) accumulation, mitochondrial health and the cell cycle progression were also evaluated in cells exposed to 6h. Results demonstrated that 6h induces apoptosis in a dose-response manner, without generating ROS and/or altering mitochondrial health. In addition, 6h disrupted the cell cycle distribution causing an increase in DNA fragmentation (Sub G0-G1), and an arrest in the G0-G1 phase. Taken together, the 6h compound revealed a strong potential as an antineoplastic agent evidenced by its cytotoxicity in leukemia cells, the activation of apoptosis and restriction of the cell cycle progression.

A Coumarin-Imidazothiadiazole Derivative, SP11 Abrogates Tumor Growth by Targeting HSP90 and Its Client Proteins.

Despite several treatment options for blood cancer, mortality remains high due to relapse and the disease's aggressive nature. Elevated levels of HSP90, a molecular chaperone essential for protein folding, are associated with poor prognosis in leukemia and lymphoma. HSP90 as a target for chemotherapy has been met with limited success due to toxicity and induction of heat shock. This study tested the activity of an HSP90 inhibitor, SP11, against leukemic cells, mouse lymphoma allograft, and xenograft models. SP11 induced cytotoxicity in vitro in leukemic cell lines and induced cell death via apoptosis, with minimal effect on normal cells. SP11 induced cell death by altering the status of HSP90 client proteins both in vitro and in vivo. SP11 reduced the tumor burden in allograft and xenograft mouse models without apparent toxicity. The half-life of SP11 in the plasma was approximately 2 h. SP11 binding was observed at both the N-terminal and C-terminal domains of HSP90. C-terminal binding was more potent than N-terminal binding of HSP90 in silico and in vitro using isothermal calorimetry. SP11 bioavailability and minimal toxicity in vivo make it a potential candidate to be developed as a novel anticancer agent.

Synthesis, in vitro cytotoxicity, molecular docking and ADME study of some indolin-2-one linked 1,2,3-triazole derivatives.

In pursuit of an anticancer lead, a library of 1,2,3-triazole derivatives (7a-x) was prepared, characterized and screened for in vitro cytotoxicity in different cell lines. Most of the compounds proved to be cytotoxic with IC50 values in the low micromolar range. Further studies showed that the most active compound 7c induces caspase-dependent apoptosis in Jurkat cells by activating both the intrinsic and the extrinsic apoptotic pathways and perturbs cell-cycle progression. Moreover, 7c did not show any genotoxic activity. Molecular docking simulations were performed against epidermal growth factor receptor (EGFR). Docking experiments showed that, compounds 7c, 7o and 7 v bind within active sites of epidermal growth factor receptor EGFR (Pdb ID: 6P8Q) by strong hydrogen bonds with residue MET793, Pi-Sulfur with residue MET790 and Pi-Alkyl type interactions with residues LEU788, ALA743. The SwissADME webserver investigation suggested that most of the synthesized compounds follow the rules of drug-likeness.

Three novel piperidones exhibit tumor-selective cytotoxicity on leukemia cells via protein degradation and stress-mediated mechanisms.

BACKGROUND: Cancer is an ongoing worldwide health problem. Although chemotherapy remains the mainstay therapy for cancer, it is not always effective and has detrimental side effects. Here, we present piperidone compounds P3, P4, and P5 that selectively target cancer cells via protein- and stress-mediated mechanisms. METHODS: We assessed typical apoptotic markers including phosphatidylserine externalization, caspase-3 activation, and DNA fragmentation through flow cytometry. Then, specific markers of the intrinsic pathway of apoptosis including the depolarization of the mitochondria and the generation of reactive oxygen species (ROS) were investigated. Finally, we utilized western blot techniques, RT-qPCR, and observed the cell cycle profile after compound treatment to evaluate the possible behavior of these compounds as proteasome inhibitors. For statistical analyses, we employed the one-way ANOVA followed by Bonferroni post hoc test. RESULTS: P3, P4, and P5 induce cytotoxic effects towards tumorigenic cells, as opposed to non-cancerous cells, at the low micromolar range. Compound treatment leads to the activation of the intrinsic pathway of apoptosis. The accumulation of poly-ubiquitinated proteins and the pro-apoptotic protein Noxa, both typically observed after proteasome inhibition, occurs after P3, P4, and P5 treatment. The stress-related genes PMAIP1, ATF3, CHAC1, MYC, and HMOX-1 were differentially regulated to contribute to the cytotoxic activity of P3-P5. Finally, compound P5 causes cell cycle arrest at the G2/M phase. CONCLUSION: Taken together, compounds P3, P4, and P5 exhibit strong potential as anticancer drug candidates as shown by strong cytotoxic potential, activation of the intrinsic pathway of apoptosis, and show typical proteasome inhibitor characteristics.

Synthesis, Cytotoxicity Evaluation and Molecular Docking of Fluorine Containing Hexahydroquinoline-3-Carbonitrile Derivatives.

BACKGROUND: Fluorine containing hexahydroquinoline-3-carbonitrile derivatives were found to have potent cytotoxicity. Furthermore, fluorine can modulate pharmacokinetic and pharmacodynamic profile of drugs. Hence, new derivatives containing fluorine were explored as potential cytotoxic agents. OBJECTIVE: Difluoro substituted compounds containing aromatic/heteroaromatic rings were designed, synthesized and screened for in vitro cytotoxicity on cancer cell lines. The active compounds were subjected to docking on Mcl-1 and ADME/T prediction. METHODS: The synthesized compounds were characterized using various spectral techniques like FT-IR, 1H NMR, 13C NMR and Mass spectra. Compounds were screened for cytotoxicity on NCI-60 cell lines at the National Cancer Institute. The active compounds were evaluated additionally by MTT and SRB assay. RESULTS: Compounds (6l and 6o) showed maximum cytotoxicity with (% GI) of 69 and 63.7 at 10 µM drug concentration, respectively. Compound 6i showed potent cytotoxicity with GI50 of 7.2 µM against Ishikawa cell line. Compound 6o was nearly as active as a reference with IC50 of 9.39 µM and 13.54 µM against HT-29 and HCT-116, respectively, and compound 6l also showed equal potency to that of reference with IC50 of 9.66 µM against Caco-2. Compounds 6i, 6o and 6l showed high docking scores, suggesting their cytotoxicity. Furthermore, ADME/T prediction revealed that all the compounds had drug-likeness properties. CONCLUSION: Enhanced lipophilic interaction of compounds due to the presence of fluorine in compounds 6i and 6l was revealed during the docking study. Compound 6i can be explored as a lead molecule against other endometrial cancer in futuristic drug development.

Curcumin derivative 1, 2-bis [(3E, 5E)-3, 5-bis [(2-chlorophenyl) methylene]-4-oxo-1-piperidyl] ethane-1, 2-dione (ST03) induces mitochondria mediated apoptosis in ovarian cancer cells and inhibits tumor progression in EAC mouse model.

Curcumin is known for its anticancer properties, but its clinical application is limited due to its poor bioavailability and chemical stability. In this study we report the curcumin derivative, ST03 (1,2-bis[(3E,5E)-3,5-bis[(2-chlorophenyl)methylene]-4-oxo-1-piperidyl]ethane-1,2-dione) exhibits ∼ 14 fold better bioavailability compared to curcumin and is detectable in plasma up to 12 h. ST03 induces ROS, activates the intrinsic apoptotic pathway as evident by disruption of mitochondrial membrane potential, and induction of proapoptotic proteins in ovarian cancer lines PA1 and A2780. ST03 also blocked the migration of ovarian cancer cells. ST03 exerted its antitumor effect in-vivo in the EAC mouse model by activating the intrinsic apoptotic pathway. Our findings demonstrate ST03, a curcumin derivative, with better bioavailability and stability with no discernable toxicity in vivo to be a promising drug candidate for anticancer therapies.

Synthesis, Anticancer Evaluation and Molecular Docking of Hexahydroquinoline Derivatives as Mcl-1 Inhibitors and Apoptosis Inducers.

BACKGROUND: Hexahydroquinoline as a small molecule was reported for good cytotoxicity and affinity towards Mcl-1. Hence, new compounds were explored as Mcl-1 inhibitors to be potent anticancer agents. OBJECTIVE: Compounds were synthesized and screened for cytotoxicity. The active compound was evaluated for cell cycle analysis, Mcl-1 inhibition, caspase-3, and caspase-9 activation. Further compounds were docked with Mcl-1 to confirm the mechanism of cytotoxicity. METHODS: Compounds were confirmed by spectral techniques and screened for cytotoxicity at National Cancer Institute (USA). The active derivatives were screened by SRB and MTT. In addition, the potent compound was studied for apoptosis and cell cycle analysis by PI staining, Mcl-1 inhibition by TR-FRET assay, and activation assay of caspase-3 and caspase-9 with the Elisa technique. RESULTS: Compounds 6a and 6b exhibited the highest growth inhibition of 86.28% and 93.20% against SR and HOP- 62, respectively. Compound 6a showed higher cytotoxicity (IC50 = 0.4 µM) against THP-1 and HL-60. It showed 15- fold higher apoptosis compared to control by arresting cells at the Sub-G1 in the cell cycle. It also showed a potent inhibition with IC50 of 1.5 µM against the anti-apoptotic protein Mcl-1, which may induce apoptosis. Furthermore, apoptosis was evidenced by an increase in cleaved caspase-3 and caspase-9 to 4.20 and 3 folds, respectively higher than control. The docking score of compound 6a was in good agreement with the Mcl-1 inhibition assay. CONCLUSION: Compound 6a inhibited anti-apoptotic protein Mcl-1 and induced activation of pro-apoptotic proteins caspase-3 and caspase-9. These dual results suggested the mechanism of apoptosis and cytotoxicity.

Synthesis, in silico ADME, molecular docking and in vitro cytotoxicity evaluation of stilbene linked 1,2,3-triazoles.

Series of (E)-1-benzyl-4-((4-styrylphenoxy)methyl)-1H-1,2,3-triazoles 7a-x were obtained by Wittig reaction between 4-((1-benzyl-1H-1,2,3-triazol-4-yl)methoxy)benzaldehydes 5a-d and benzyl triphenylphosphonium halides 6a-f in benzene. The structures of the synthesized compounds were confirmed by FTIR, NMR (1H and 13C NMR) spectroscopy, and mass spectrometry. All synthesized compounds were screened for their cytotoxic activity against human cancer cell lines including pancreatic carcinoma, colorectal carcinoma, lung carcinoma, and leukemias such as acute lymphoblastic, chronic myeloid, and non-Hodgkinson lymphoma cell lines. In vitro cytotoxicity data showed that compounds 7c, 7e, 7h, 7j, 7k, 7r, and 7w were moderately cytotoxic (11.6-19.3 µM) against the selected cancer cell lines. These cytotoxicity findings were supported using molecular docking studies of the compounds against 1TUB receptor. The drug-likeness properties of the compounds evaluated by in silico ADME analyses. Resveratrol linked 1,2,3-triazoles were more sensitive towards human carcinoma cell lines but least sensitive towards leukemia and lymphoma cell lines.

Synthesis, Molecular Docking and Preliminary Antileukemic Activity of 4-Methoxybenzyl Derivatives Bearing Imidazo[2,1-b][1,3,4]thiadiazole.

In this study, we synthesized 22 compounds in a series with various substitution on imidazo[2,1-b][1,3,4]thiadiazole. The potential cytotoxic activity of these compounds investigated in leukemia cell lines by Differential Nuclear Staining (DNS). Our results identified two compounds, 2-(4-methoxybenzyl)-6-(2-oxo-2H-chromen-3-yl)imidazo[2,1-b][1,3,4]thiadiazol-5-yl thiocyanate and 6-(4-chlorophenyl)-2-(4-methoxybenzyl)imidazo[2,1-b][1,3,4]thiadiazole-5-carbaldehyde, exhibited the most cytotoxic effect against murine leukemia cells (L1210), human T-lymphocyte cells (CEM) and human cervix carcinoma cells (HeLa) with IC50 values ranging between 0.79 and 1.6 µM. The results indicate that 2-(4-methoxybenzyl)-6-(2-oxo-2H-chromen-3-yl)imidazo[2,1-b][1,3,4]thiadiazol-5-yl thiocyanate is inducing phosphatidylserine externalization and caspase-3 activation which are both a hallmark of apoptosis. Docking studies showed that 2-(4-methoxybenzyl)-6-(2-oxo-2H-chromen-3-yl)imidazo[2,1-b][1,3,4]thiadiazol-5-yl thiocyanate binds within the active sites of transforming growth factor beta (TGF-ß) type I receptor kinase domain by strong hydrogen binding and hydrophobic interactions.

ST09, A Novel Curcumin Derivative, Blocks Cell Migration by Inhibiting Matrix Metalloproteases in Breast Cancer Cells and Inhibits Tumor Progression in EAC Mouse Tumor Models.

PURPOSE: Curcumin is known for its anticancer and migrastatic activity in various cancers, including breast cancer. Newer curcumin derivatives are being explored to overcome limitations of curcumin like low bioavailability, stability, and side effects due to its higher dose. In this study, the synthesis of ST09, a novel curcumin derivative, and its antiproliferative, cytotoxic, and migrastatic properties have been explored both in vitro and in vivo. METHODS: After ST09 synthesis, anticancer activity was studied by performing standard cytotoxicity assays namely, lactate dehydrogenase (LDH) release assay, 3-(4, 5-dimethylthiazol-2-yl)-2-5-diphenyletrazolium bromide (MTT), and trypan blue exclusion assay. Annexin-FITC, cell cycle analysis using flow cytometry, and Western blotting were performed to elucidate cell death mechanisms. The effect on the inhibition of cell migration was studied by transwell migration assay. An EAC (Ehrlich Ascites carcinoma) induced mouse tumor model was used to study the effect of ST09 on tumor regression. Drug toxicity was measured using aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), and flow-cytometry based lymphocyte count. Histological analysis was performed for assessment of any tissue injury post ST09 treatment. RESULTS: ST09 shows an approximate 100-fold higher potency than curcumin, its parent compound, on breast tumor cell lines MCF-7 and MDA-MB231. ST09 arrests the cell cycle in a cell type-specific manner and induces an intrinsic apoptotic pathway both in vitro and in vivo. ST09 inhibits migration by downregulating matrix metalloprotease 1,2 (MMP1,2) and Vimentin. In vivo, ST09 administration led to decreased tumor volume in a mouse allograft model by boosting immunity with no significant drug toxicity. CONCLUSION: ST09 exhibits antiproliferative and cytotoxic activity at nanomolar concentrations. It induces cell death by activation of the intrinsic pathway of apoptosis both in vitro and in vivo. It also inhibits migration and invasion. This study provides evidence that ST09 can potentially be developed as a novel antitumor drug candidate for highly metastatic and aggressive breast cancer.

Investigation of anti-cancer and migrastatic properties of novel curcumin derivatives on breast and ovarian cancer cell lines.

BACKGROUND: Curcumin is known for its multitude of medicinal properties, including anti-cancer and migrastatic activity. Efforts to overcome poor bioavailability, stability, and side effects associated with the higher dose of curcumin has led to the development of newer derivatives of curcumin. Thus, the focus of this study is to screen novel curcumin derivatives, namely ST03 and ST08, which have not been reported before, for their cytotoxicity and migrastatic property on cancer cells. METHODS: Anti-cancer activity of ST03 and ST08 was carried out using standard cytotoxicity assays viz., LDH, MTT, and Trypan blue on both solid and liquid cancer types. Flow cytometric assays and western blotting was used to investigate the cell death mechanisms. Transwell migration assay was carried out to check for migrastatic properties of the compounds. RESULTS: Both the compounds, ST03 and ST08, showed ~ 100 fold higher potency on liquid and solid tumour cell lines compared to its parent compound curcumin. They induced cytotoxicity by activating the intrinsic pathway of apoptosis in the breast (MDA-MB-231) and ovarian cancer cell lines (PA-1) bearing metastatic and stem cell properties, respectively. Moreover, ST08 also showed inhibition on breast cancer cell migration by inhibiting MMP1 (matrix metalloproteinase 1). CONCLUSION: Both ST03 and ST08 exhibit anti-cancer activity at nanomolar concentration. They induce cell death by activating the intrinsic pathway of apoptosis. Also, they inhibit migration of the cancer cells by inhibiting MMP1 in breast cancer cells.

Effects of green synthesised silver nanoparticles (ST06-AgNPs) using curcumin derivative (ST06) on human cervical cancer cells (HeLa) in vitro and EAC tumor bearing mice models.

BACKGROUND: In recent years, green synthesized silver nanoparticles have been increasingly investigated for their anti-cancer potential. In the present study, we aimed at the biosynthesis of silver nanoparticles (AgNPs) using a curcumin derivative, ST06. Although, the individual efficacies of silver nanoparticles or curcumin derivatives have been studied previously, the synergistic cytotoxic effects of curcumin derivative and silver nanoparticles in a single nanoparticulate formulation have not been studied earlier specifically on animal models. This makes this study novel compared to the earlier synthesized curcumin derivative or silver nanoparticles studies. The aim of the study was to synthesize ST06 coated silver nanoparticles (ST06-AgNPs) using ST06 as both reducing and coating agent. METHODS: The synthesized nanoparticles AgNPs and ST06-AgNPs were characterised for the particle size distribution, morphology, optical properties and surface charge by using UV-visible spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). Elemental composition and structural properties were studied by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction spectroscopy (XRD). The presence of ST06 as capping agent was demonstrated by Fourier transform infrared spectroscopy (FTIR). RESULTS: The synthesized nanoparticles (ST06-AgNPs) were spherical and had a size distribution in the range of 50-100 nm. UV-Vis spectroscopy displayed a specific silver plasmon peak at 410 nm. The in vitro cytotoxicity effects of ST06 and ST06-AgNPs, as assessed by MTT assay, showed significant growth inhibition of human cervical cancer cell line (HeLa). In addition, studies carried out in EAC tumor-induced mouse model (Ehrlich Ascites carcinoma) using ST06-AgNPs, revealed that treatment of the animals with these nanoparticles resulted in a significant reduction in the tumor growth, compared to the control group animals. CONCLUSION: In conclusion, green synthesized ST06-AgNPs exhibited superior anti-tumor efficacy than the free ST06 or AgNPs with no acute toxicity under both in vitro and in vivo conditions. The tumor suppression is associated with the intrinsic apoptotic pathway. Together, the results of this study suggest that ST06-AgNPs could be considered as a potential option for the treatment of solid tumors.

Autocyclized and oxidized forms of SCR7 induce cancer cell death by inhibiting nonhomologous DNA end joining in a Ligase IV dependent manner.

Nonhomologous DNA end joining (NHEJ) is the major DNA double-strand break (DSB) repair pathway in mammals. Previously, we have described a small molecule inhibitor, SCR7, which can inhibit NHEJ in a Ligase IV-dependent manner. Administration of SCR7 within the cells resulted in the accumulation of DNA breaks, cell death, and inhibition of tumor growth in mice. In the present study, we report that parental SCR7, which is unstable, can be autocyclized into a stable form. Both parental SCR7 and cyclized SCR7 possess the same molecular weight (334.09) and molecular formula (C18 H14 N4 OS), whereas its oxidized form, SCR7-pyrazine, possesses a different molecular formula (C18 H12 N4 OS), molecular weight (332.07), and structure. While cyclized form of SCR7 showed robust inhibition of NHEJ in vitro, both forms exhibited efficient cytotoxicity. Cyclized and oxidized forms of SCR7 inhibited DNA end joining catalyzed by Ligase IV, whereas their impact was minimal on Ligase III, Ligase I, and T4 DNA Ligase-mediated joining. Importantly, both forms inhibited V(D)J recombination, although the effect was more pronounced for SCR7-cyclized. Both forms blocked NHEJ in a Ligase IV-dependent manner leading to the accumulation of DSBs within the cells. Although cytotoxicity due to SCR7-cyclized was Ligase IV specific, the pyrazine form exhibited nonspecific cytotoxicity at higher concentrations in Ligase IV-null cells. Finally, we demonstrate that both forms can potentiate the effect of radiation. Thus, we report that cyclized and oxidized forms of SCR7 can inhibit NHEJ in a Ligase IV-dependent manner, although SCR7-pyrazine is less specific to Ligase IV inside the cell.

3,5-Bis(3-dimethylaminomethyl-4-hydroxybenzylidene)-4-piperidone and related compounds induce glutathione oxidation and mitochondria-mediated cell death in HCT-116 colon cancer cells.

This study aims at investigating the cytotoxicity and some of the modes of action of 3,5-bis(3-dimethylamino-4-hydroxybenzylidene)-4-piperidone trihydrochloride 3 and two related compounds 2 (which lacks the dimethylaminomethyl groups) and 4 (which has an additional dimethylaminoethyl substituent in both aryl rings) in order to ascertain the contribution of dimethylaminoethyl substituent to bioactivity. The bioactivities of 2-4 were compared with curcumin 5. Both 2 and 3 displayed submicromolar GI50 values towards HCT-116 cells and were significantly more potent than 4, 5 and 5-fluorouracil (5-FU). All of the compounds displayed greater toxicity towards HCT-116 cells than human CRL-1790 non-malignant colon cells. In HCT-116 cells, the compounds 2, 3 and 5 increased the ratio of oxidised to reduced glutathione and destabilized the mitochondrial membrane potential. Both 2 and 5 produced an increase in mitochondrial superoxide and a burst in intracellular reactive oxygen species in HCT 116 cells. In addition, 2 and 4 stimulated respiration in rat liver mitochondria while 2 and 5 induced mitochondrial swelling. The results suggest that 2 and 5 cause oxidation or cross-linking of the thiols which control the mitochondrial permeability transition.

Novel BCL2 inhibitor, Disarib induces apoptosis by disruption of BCL2-BAK interaction.

Apoptosis is a highly regulated pathway of programmed cell death relying on the fine balance between pro and antiapoptotic binding partners. Overexpression of the antiapoptotic protein BCL2 in several cancers makes it an ideal target for chemotherapy, with minimum side effects. In one of our previous studies, we designed, synthesized and characterized Disarib, a BCL2-specific small molecule inhibitor. Interestingly, Disarib showed a novel mode of BCL2 inhibition, by predominantly binding to its BH1 domain, as compared to the BH3-specific action of other known BCL2 inhibitors. Here, we investigate the mechanism by which Disarib induces cell death, upon binding to BCL2. We find that Disarib specifically disrupted the BCL2-BAK interaction, but not that of BCL2-BAX or other members of the proapoptotic family such as PUMA and BIM, in vitro. Biochemical and biophysical studies demonstrate Disarib-induced inhibition of BCL2-BAK interaction with a Ki of 12.76nM. Genetic knockout cells of BAK/BAX and double knockout (DKO) cells confirmed a BAK-specific action of Disarib, thereby facilitating apoptosis. Importantly, intracellular FRET in BAK/BAX single and double knockout cells demonstrated BCL2-BAK disruption, and activation of intrinsic pathway of apoptosis upon Disarib treatment. Thus, we report a unique mechanism of action of a BCL2 inhibitor, Disarib, by specifically targeting the interaction of BCL2-BAK, while sparing that of other proapoptotic binding partners.

SYNTHESIS AND CYTOTOXIC EVALUATION OF SOME 2-{4-[(2-OXO-1,2-DIHYDRO-3H-INDOL-3-YLIDENE)METHYL] PHENOXY}-N-PHENYLACETAMIDE.

A series of 2-oxindole derivatives were synthesized and evaluated for cytotoxic activity against different human and murine cancer cell lines and cancer chemopreventive activity. Among the tested compounds VS-06, 08, 12 and 17 displayed cytotoxic activity in the range of 5.0 to 8.5 pM against human T-lymphocyte cells (CEM). Results showed that molecules with electron withdrawing substituent at 4 position of N-phenylacetamide group exhibited an increase in activity against the human tumor cell line CEM. The cancer chemo- preventive effect of VS-01 (IC50 = 451 nM) displayed equipotent activity in comparison to standard oleanolic acid (IC50 = 449 nM).

Identification and characterization of novel ligase I inhibitors.

The terminal step of ligation of single and/or double-strand breaks during physiological processes such as DNA replication, repair and recombination requires participation of DNA ligases in all mammals. DNA Ligase I has been well characterised to play vital roles during these processes. Considering the indispensable role of DNA Ligase I, a therapeutic strategy to impede proliferation of cancer cells is by using specific small molecule inhibitors against it. In the present study, we have designed and chemically synthesised putative DNA Ligase I inhibitors. Based on various biochemical and biophysical screening approaches, we identify two prospective DNA Ligase I inhibitors, SCR17 and SCR21. Both the inhibitors blocked ligation of nicks on DNA in a concentration-dependent manner, when catalysed by cell-free extracts or purified Ligase I. Docking studies in conjunction with biolayer interferometry and gel shift assays revealed that both SCR17 and SCR21 can bind to Ligase I, particularly to the DNA Binding Domain of Ligase I with KD values in nanomolar range. The inhibitors did not show significant affinity towards DNA Ligase III and DNA Ligase IV. Further, addition of Ligase I could restore the joining, when the inhibitors were treated with testicular cell-free extracts. Ex vivo studies using multiple assays showed that even though cell death was limited in the presence of inhibitors in cancer cells, their proliferation was compromised. Hence, we identify two promising DNA Ligase I inhibitors, which can be used in biochemical and cellular assays, and could be further modified and optimised to target cancer cells. © 2016 Wiley Periodicals, Inc.

A novel inhibitor of BCL2, Disarib abrogates tumor growth while sparing platelets, by activating intrinsic pathway of apoptosis.

Antiapoptotic protein BCL2, serves as an excellent target for anticancer therapy owing to its increased level in cancers. Previously, we have described characterization of a novel BCL2 inhibitor, Disarib, which showed selective cytotoxicity in BCL2 'high' cancer cells and CLL patient cells. Here, we have investigated the mechanism of Disarib-induced cytotoxicity, and compared its efficacy with a well-established BCL2 inhibitor, ABT199. We show that Disarib administration caused tumor regression in mouse allograft and xenograft models, exhibited platelet sparing property and did not exhibit significant side effects. Importantly, comparison between Disarib and ABT199, revealed higher efficacy for Disarib in mouse tumor model and cancer cell lines. Disarib induced cell death by activating intrinsic apoptotic pathway. Interestingly, Disarib showed synergism with paclitaxel, suggesting its potential for combination therapy. Thus, we provide mechanistic insights into the cell death pathways induced by Disarib, report that Disarib exhibited better effect than currently used ABT199 and demonstrate its combinatorial potential with paclitaxel.

The crystal structure of 6-(4-chloro-phen-yl)-2-(4-methyl-benz-yl)imidazo[2,1-b][1,3,4]thia-diazole-5-carbaldehyde.

In the title imidazo[2,1-b][1,3,4]thia-diazole derivative, C19H14ClN3OS, the 4-methyl-benzyl and chloro-phenyl rings are inclined to the planar imidazo[2,1-b][1,3,4]thia-diazole moiety (r.m.s. deviation = 0.012 Å) by 64.5 (1) and 3.7 (1)°, respectively. The mol-ecular structure is primarily stabilized by a strong intra-molecular C-H⋯O hydrogen bond, leading to the formation of a pseudo-seven-membered S(7) ring motif, and a short intra-molecular C-H⋯N contact forming an S(5) ring motif. In the crystal, mol-ecules are linked by pairs of C-H⋯S hydrogen bonds, forming inversion dimers. The dimers are linked by C-H⋯O and C-H⋯π inter-actions, forming chains propagating along [110].

A Novel Resveratrol Based Tubulin Inhibitor Induces Mitotic Arrest and Activates Apoptosis in Cancer Cells.

Resveratrol is one of the most widely studied bioactive plant polyphenols which possesses anticancer properties. Previously we have reported synthesis, characterization and identification of a novel resveratrol analog, SS28. In the present study, we show that SS28 induced cytotoxicity in several cancer cell lines ex vivo with an IC50 value of 3-5 µM. Mechanistic evaluation of effect of SS28 in non-small cell lung cancer cell line (A549) and T-cell leukemic cell line (CEM) showed that it inhibited Tubulin polymerization during cell division to cause cell cycle arrest at G2/M phase of the cell cycle at 12-18 h time period. Immunofluorescence studies confirmed the mitotic arrest upon treatment with SS28. Besides, we show that SS28 binds to Tubulin with a dissociation constant of 0.414 ± 0.11 µM. Further, SS28 treatment resulted in loss of mitochondrial membrane potential, activation of Caspase 9 and Caspase 3, leading to PARP-1 cleavage and finally cell death via intrinsic pathway of apoptosis. Importantly, treatment with SS28 resulted in regression of tumor in mice. Hence, our study reveals the antiproliferative activity of SS28 by disrupting microtubule dynamics by binding to its cellular target Tubulin and its potential to be developed as an anticancer molecule.