Discovery of Substituted 2-oxoquinolinylthiazolidin-4-one Analogues as Potential EGFRK Inhibitors in Lung Cancer Treatment.

PURPOSE: Cancer is the second leading cause of death globally and is responsible for an estimated 9.6 million deaths in 2018. Globally, about 1 in 6 deaths is due to cancer and the chemotherapeutic drugs available have high toxicity and have reported side effects hence, there is a need for the synthesis of novel drugs in the treatment of cancer. METHODS: The current research work dealt with the synthesis of a series of 3-(3-acetyl-2-oxoquinolin-1-(2H)-yl-2-(substitutedphenyl)thiazolidin-4-one (Va-j) derivatives and evaluation of their in-vitro anticancer activity. All the synthesized compounds were satisfactorily characterized by IR and NMR data. Compounds were further evaluated for their in-vitro anticancer activity against A-549 (lung cancer) cell lines. The in-vitro anticancer activity was based upon the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay method. RESULTS: The synthesized compounds exhibited satisfactory anticancer properties against the A-549 cell line. The compound (VH): showed the highest potency amongst the tested derivatives against the A-549 cell line with IC50 values of 100 µg/ml respectively and was also found to be more potent than Imatinib (150 µg/ml) which was used as a standard drug. Molecular docking studies of the titled compounds (Va-j) were carried out using AutoDock Vina/PyRx software. The synthesized compounds exhibited well-conserved hydrogen bonds with one or more amino acid residues in the active pocket of the EGFRK tyrosine kinase domain (PDB 1m17). CONCLUSION: Among all the synthesized analogues, the binding affinity of the compound (Vh) was found to be higher than other synthesized derivatives and a molecular dynamics simulation study explored the stability of the docked complex system.

Thioproline-Based Oxidation Strategy for Direct Preparation of N-Terminal Thiazolidine-Containing Peptide Thioesters from Peptide Hydrazides.

We describe a simple and robust oxidation strategy for preparing N-terminal thiazolidine-containing peptide thioesters from peptide hydrazides. We find for the first time that l-thioproline can be used as a protective agent to prevent the nitrosation of N-terminal thiazolidine during peptide hydrazide oxidation. The thioproline-based oxidation strategy has been successfully applied to the chemical synthesis of CC chemokine ligand-2 (69aa) and omniligase-C (113aa), thereby demonstrating its utility in hydrazide-based native chemical ligation.

One-Pot Synthesis of Novel 2-Imino-5-Arylidine-Thiazolidine Analogues and Evaluation of Their Anti-Proliferative Activity against MCF7 Breast Cancer Cell Line.

An efficient surface-mediated synthetic method to facilitate access to a novel class of thiazolidines is described. The rationale behind the design of the targeted thiazolidines was to prepare stable thiazolidine analogues and evaluate their anti-proliferative activity against a breast cancer cell line (MCF7). Most of the synthesized analogues exhibited increased potency ranging from 2-15-fold higher compared to the standard reference, cisplatin. The most active thiazolidines contain a halogenated or electron withdrawing group attached to the N-phenyl ring of exocyclic 2-imino group. However, combination of the two substituents did not enhance the activity. The anti-proliferative activity was measured in terms of IC50 values using an MTT assay.

Novel 2-phenyl-3-(Pyridin-2-yl) thiazolidin-4-one derivatives as potent inhibitors for proliferation of osteosarcoma cells in vitro and in vivo.

Due to unknown pathogenesis and unidentified drug target, no drug for the treatment of osteosarcoma (OS) has been launched to the market. Herein, thiazolidinone 1a was discovered as a hit compound by phenotypic screening with an in-house patrimonial collection of structural diversity. The following SAR (Structure-Activity Relationship) study affords the final water-soluble lead compound (R)-8i as a potential inhibitor for the proliferation of OS cells by the modulation of solubility of the compounds with remarkable cellular potency (IC50 = 21.9 nM for MNNG/HOS cells) and in vivo efficacy (52.9% inhibition OS growth in mice), as well as pharmacokinetic properties. (R)-8i also significantly suppresses OS cell migration in vitro and showed to be well-tolerated. Our preliminary investigation shows that the effects of (R)-8i are not dependent on p53 and myoferlin (MYOF). These results suggest that (R)-8i might be a potential drug candidate for OS treatment.

2-Thioxothiazolidin-4-one Analogs as Pan-PIM Kinase Inhibitors.

Proviral integration site for Moloney murine leukemia virus (PIM) kinases are proto-oncogenic kinases involved in the regulation of several cellular processes. PIM kinases are promising targets for new drug development because they play a major role in many cancer-specific pathways, such as survival, apoptosis, proliferation, cell cycle regulation, and migration. Here, 2-thioxothiazolidin-4-one derivatives were synthesized and evaluated as potent pan-PIM kinase inhibitors. Optimized compounds showed single-digit nanomolar IC50 values against all three PIM kinases with high selectivity over 14 other kinases. Compound 17 inhibited the growth of Molm-16 cell lines (EC50 = 14 nM) and modulated the expression of pBAD and p4EBP1 in a dose-dependent manner.

Structure based designing of thiazolidinone-pyrimidine derivatives as ERK2 inhibitors: Synthesis and in vitro evaluation.

Breast cancer has been associated with an overexpression of various molecular targets; accordingly, various target-specific chemotherapeutic agents have been developed. Inhibition of ERK2, a member of MAPK pathway, is an important target involved in the treatment of both oestrogen receptor-positive and triple-negative breast cancer. Thus, in continuation of our previous work on the ERK2 target, we here report novel inhibitors of this kinase. Out of three lead molecules reported in our previous study, we selected the thiazolidinone-pyrimidine scaffold for further development of small molecule inhibitors of ERK2. Analogues of the lead molecule were docked in the target kinase, followed by molecular dynamic simulations and MM-GBSA calculations. Analogues maintaining key interactions with amino acid residues in the ATP-binding domain of ERK2 were selected and duly synthesized. In vitro biochemical evaluation of these molecules against ERK2 kinase disclosed that two molecules possess significant kinase inhibitory potential with IC50 values ≤ 0.5 µM.

Novel thiazolidine derivatives as potent selective pro-apoptotic agents.

A series of 2-arylthiazolidine-4-carboxylic acid amide derivatives were synthesized and their cytotoxic activity against three cancer cell lines (PC-3, SKOV3 and MDA-MB231) was evaluated. Various structural modifications were tried including modifications of the length of the amide chain and modifications of the 2-aryl part using disubstituted phenyl and thiophene derivatives. The structure activity relationship was evaluated based on the in vitro biological evaluation against the above mentioned three cancer cell lines. The most selective compounds towards cancer cells were further evaluated against DLD-1, NCI-H520, Du145, MCF-7 and NCI-N87 cancer cells. The dodecyl amide having the 4-bromothienyl as the 2-aryl, compound 2e, exhibited the highest selectivity for cancer cells vs non-tumor cells. Mechanistic studies of the anticancer effect of compound 2e in prostate cancer PC-3 and colorectal cancer DLD-1 cells revealed that 2e could prevent the cell cycle in the G0/G1 phase by up-regulating the expression of p21 and reducing the expression of CDK2 and cyclin E. It increased the pro-apoptotic protein Bax and cleaved caspase 3, and down-regulated the expression of anti-apoptotic protein Bcl-2 to induce apoptosis. In addition, 2e also downregulated AKT, N-cadherin, and vimentin proteins expression giving indication that 2e inhibit the PI3K/AKT pathway to regulate cell cycle arrest and induce apoptosis, and can regulate the expression of epithelial-mesenchymal transition-related proteins.

Synthesis, Characterization, Molecular Docking, In Vitro Biological Evaluation and In Vitro Cytotoxicity Study of Novel Thiazolidine-4-One Derivatives as Anti-Breast Cancer Agents.

BACKGROUND: Thiazolidine-4-one is a promising class of heterocyclic compounds with interesting pharmacological and biological activities, such as anticancer and antibacterial. Therefore, many researchers have synthesized thiazolidine-4-ones and evaluated their biological potential for developing new drugs. OBJECTIVE: In this study, two novel thiazolidine-4-one derivatives (T1 and T2) were synthesized and evaluated for their antibacterial activity toward Staphylococcus aureus, Escherichia coli, and Proteus mirabilis. Also, the cytotoxic activities of compounds T1 and T2 were estimated against MCF-7 (HER2+, ER+, and ER+) and MDAMB- 231 (triple-negative) human breast cancer cell lines. The chemical structures of the compounds T1 and T2 were proven using spectral techniques (FT-IR, 1HNMR, and 13CNMR) and CHN elemental analysis. METHODS: The synthesis of thiazolidine-4-one compounds was performed in two steps. The first step consisted of the formation of Schiff bases S1 and S2. In the second step, the synthesized Schiff bases were reacted with thioglycolic acid to prepare thiazolidine-4-one compounds. Hemolysis assay, molecular docking, cytotoxicity activity (MTT assay), and antibacterial activity (disc diffusion assay) were studied. RESULTS: The hemolysis study demonstrated that the hemolytic ratio of compounds T1 and T2 at (1, 2, and 3) mg/ml was less than 4%. MTT assay showed that 100 µg/ml of compounds T1 and T2 diminish the MCF-7 cell growth up to 80.05 ± 1.72 and 69.85 ± 3.26 respectively after 72hr., while the same concentration of compounds T1 and T2 reduces the MDA-MB-231 cell growth up 70.28 ± 2.31 and 57.15 ± 1.49, respectively. The inhibition zones of T1 and T2 were 12 mm at 50 mg/ml and 10 mm at 5 mg/ml in E. coli bacteria. Furthermore, a docking study was carried out to investigate the affinity and binding mode of compounds T1 and T2 towards the ERα, VEGF, and HER2 protein receptors in breast cancer cells. Data obtained from the docking study were exactly identical to that obtained from in vitro cytotoxicity assay. CONCLUSION: The results proved that T1 is an optimal anticancer agent toward breast cancer cells and the hemolysis study indicates the use of safety inside the body for compound T1. Synthesized compound T1 was most effective against MCF-7 cells compared to MDA-MB-231 cells and more effective than the reference drug tamoxifen in breast cell lines. The high cytotoxicity of T1 on the growth of MCF-7 cells because T1 binds with a high degree of affinity to the estrogen and HER2 receptors, which in turn inhibits cell proliferation and induces apoptosis.

Design, synthesis, and anticancer activity of novel 4-thiazolidinone-phenylaminopyrimidine hybrids.

4-Thiazolidinones and phenylaminopyrimidines are known as anticancer agents. Imatinib is the pioneer phenylaminopyrimidine derivative kinase inhibitor, which is used for the treatment of chronic myeloid leukemia. With a hybrid approach, a novel series of 5-benzylidene-2-arylimino-4-thiazolidinone derivatives containing phenylaminopyrimidine core were designed, synthesized, and tested for their anticancer activity on K562 (chronic myeloid leukemia), PC3 (prostat cancer), and SHSY-5Y (neuroblastoma) cells. Since superior anticancer activity was observed on K562 cells, further biological studies of selected compounds (8, 15, and 34) were performed on K562 cells. For the synthesis of designed compounds, thiourea compounds were converted to 2-imino-1,3-thiazolidin-4-ones with α-chloroacetic acid in the presence of sodium acetate. 5-Benzylidene-2-imino-1,3-thiazolidin-4-one derivatives were obtained by Knoevenagel condensation of 2-imino-1,3-thiazolidin-4-ones with related aldehydes. Compounds 8, 15, and 34 were evaluated for cell viability, apoptosis studies, cell cycle experiments, and DNA damage assays. IC50 values of compounds 8, 15, and 34 were found as 5.26 ± 1.03, 3.52 ± 0.91, and 8.16 ± 1.27 µM, respectively, in K562 cells. Preferably, these compounds showed less toxicity towards L929 cells compared to imatinib. Furthermore, compounds 8 and 15 significantly induced early and late apoptosis in a time-dependent manner. Compounds 15 and 34 induced cell cycle arrest at G0/G1 phase and compound 8 caused cell cycle arrest at G2/M phase. Based on DNA damage assay, compounds 8 and 15 were found to be more genotoxic than imatinib towards K562 cells. To put more molecular insight, possible Abl inhibition mechanisms of most active compounds were predicted by molecular docking studies. In conclusion, a novel series of 5-benzylidene-2-arylimino-4-thiazolidinone derivatives and their promising anticancer activities were reported herein.

Design and synthesis of novel 4-thiazolidinone derivatives with promising anti-breast cancer activity: Synthesis, characterization, in vitro and in vivo results.

Novel lead compounds as anticancer agents with the ability to circumvent emerging drug resistance have recently gained a great deal of interest. Thiazolidinones are among such compounds with well-established biological activity in the field of oncology. Here, we designed, synthesized and characterized a series of thiazolidinone structures (8a-8k). The results of anti-proliferative assay led to the discovery of compound 8j with a high potent cytotoxic effect using colon, liver and breast cancer cells. Furthermore, MDA-MB-231 and 4T1 cell lines were used to represent triple negative breast cancer (TNBC). Next, a number of in vitro and in vivo evaluations were carried out to demonstrate the potential activity against TNBC and also elucidate the possible mechanism of cell death induction. Our in vitro outcomes exhibited an impressive anticancer activity for compound 8j toward MDA-MB-231 cells through inducing apoptosis and a remarkable anti-metastatic feature via suppressing MMP-9 expression as well. Consistently, the in vivo and immunohistopathologic evaluations demonstrated that this compound significantly inhibited the 4T1 induced tumor growth and its metastasis to the lung. Altogether, among numerous thiazolidinone derivatives, compound 8j might represent a promising anticancer agent for TNBC, which is a major concern in the developed and developing countries.

Design, synthesis, and biological evaluation of imidazopyridine-linked thiazolidinone as potential anticancer agents.

In this study, two series of imidazopyridine-linked thiazolidinone rings (5a-h and 6a-h) constituting 16 new compounds were synthesized and tested for their antiproliferative activity against a panel of three human cancer cell lines, that is, MCF-7 (human breast cancer), A549 (human lung cancer), and DU145 (human prostate cancer). Three compounds, 5h, 6f, and 6h, exhibited remarkable results against all three cell lines, but compound 6h was found to be the most active one against the breast cancer cell line. Among all the synthesized compounds, 6h displayed the highest antioxidant results. Furthermore, the potent compounds 5h, 6f, and 6h showed no signs of toxicity at doses ranging from 50 to 500 mg/kg of animal body weight. The biochemical parameters (SGOT and SGPT) of compound 6h nearly matched the control in hepatotoxicity studies. The molecular docking and MM-GBSADG binding studies are in agreement with the in vitro anticancer and antioxidant activity results. The most promising compound 6h was found to have the highest docking score and binding energy, and its absorption, distribution, metabolism, and excretion (ADME) parameters are in the acceptable range. Thus, it can be concluded that 6h, an imidazopyridine derivative endowed with a thiazolidinone ring system, has the potential to be developed as an anticancer agent.

Discovery and Structure-Activity Relationship Study of (Z)-5-Methylenethiazolidin-4-one Derivatives as Potent and Selective Pan-phosphatidylinositol 5-Phosphate 4-Kinase Inhibitors.

Due to their role in many important signaling pathways, phosphatidylinositol 5-phosphate 4-kinases (PI5P4Ks) are attractive targets for the development of experimental therapeutics for cancer, metabolic, and immunological disorders. Recent efforts to develop small molecule inhibitors for these lipid kinases resulted in compounds with low- to sub-micromolar potencies. Here, we report the identification of CVM-05-002 using a high-throughput screen of PI5P4Kα against our in-house kinase inhibitor library. CVM-05-002 is a potent and selective inhibitor of PI5P4Ks, and a 1.7 Å X-ray structure reveals its binding interactions in the ATP-binding pocket. Further investigation of the structure-activity relationship led to the development of compound 13, replacing the rhodanine-like moiety present in CVM-05-002 with an indole, a potent pan-PI5P4K inhibitor with excellent kinome-wide selectivity. Finally, we employed isothermal cellular thermal shift assays (CETSAs) to demonstrate the effective cellular target engagement of PI5P4Kα and -ß by the inhibitors in HEK 293T cells.

Synthesis of (4R)-thiazolidine carboxylic acid and evaluation of antioxidant potential.

We report here the synthesis as well as antioxidant activity of a series of 2-aryl thiazolidine-4-carboxylic acids, including two novel derivatives. They were synthesized by nucleophilic cyclic condensation of L-cysteine hydrochloride with a range of aromatic aldehydes. Their in vitro antioxidant activity was evaluated by DPPH radical scavenging assay. It was observed that the aromatic substituent at C-2 of thiazolidine ring effects the antioxidant potential of the thiazolidine derivatives. The nature and position of the substituents on aromatic ring were correlated with antioxidant activity. Compounds with -OCH3 group on aromatic ring showed a better radical scavenging property than the other groups such as -Cl, -F, and -NO2. The presence of phenyl ring thus enhanced radical scavenging activity.

Synthesis of a novel series of (Z)-3,5-disubstituted thiazolidine-2,4-diones as promising anti-breast cancer agents.

A novel series of (Z)-3,5-disubstituted thiazolidine-2,4-diones 4-16 has been designed and synthesized. Preliminary screening of these compounds for their anti-breast cancer activity revealed that compounds 5, 7, and 9 possess the highest anti-cancer activities. The anti-tumor effects of compounds 5, 7, and 9 were evaluated against human breast cancer cell lines (MCF-7 and MDA-MB-231) and human breast cancer cells. They were also evaluated against normal non-cancerous breast cells, isolated from the same patients, to conclude about their use in a potential targeted therapy. Using MTT uptake method, these three compounds 5, 7, and 9 blunt the proliferation of these cancer cells in a dose-dependent manner with an IC50 of 1.27, 1.50 and 1.31 µM respectively. Interestingly, using flow cytometry analysis these three compounds significantly mediated apoptosis of human breast cancer cells without affecting the survival of normal non-cancerous breast cells that were isolated from the same patients. Mechanistically, these compounds blunt the proliferation of MCF-7 breast cancer cells by robustly decreasing the phosphorylation of AKT, mTOR and the expression of VEGF and HIF-1α. Most importantly, compounds 5, 7, and 9 without affecting the phosphorylation and expression of these crucial cellular factors in normal non-cancerous breast cells that were isolated from the same patients. Additionally, using Western blot analysis the three compounds significantly (P < 0.05) decreased the expression of the anti-apoptotic Bcl-2 members (Bcl-2, Bcl-XL and Mcl-1) and increased the expression of the pro-apoptotic Bcl-2 members (Bak, Bax and Bim) in MCF-7, MDA-MB-231 and human breast cancer cells making these breast cancer cells susceptible for apoptosis induction. Taken together, these data provide great evidences for the inhibitory activity of these compounds against breast cancer cells without affecting the normal breast cells.

Design, Synthesis and In vitro Biological Activity of Some New 1,3- thiazolidine-4-one Derivatives as Chemotherapeutic Agents using Virtual Screening Strategies.

AIMS: Designing of a new series of derivatives possessing thiazolidine-4-one moiety, their virtual screening using various computational tools, synthesis of prioritized compounds, spectral characterization and biological evaluation along with the comparison of in silico & in vitro results. BACKGROUND: WHO has come up with a list of antibiotic-resistant "priority pathogens" i.e. families of bacteria, that pose the greatest threat to human health. Some virulent bacteria are focused in the present study namely Mycobacterium tuberculosis (multi drug resistant), Staphylococcus aureus (methicillin-resistant) Streptococcus pneumoniae, (penicillin-non-susceptible) and Pseudomonas aeruginosa (Carbapenem-resistant) One of the neglected pathogenic disease which needs an urgent attention is Leishmaniasis which has a major burden among the poorest segments of populations in Asia, Africa, and South America. OBJECTIVE: 1. To design of a series of new heteroaryl-1,3-thiazolidin-4-one derivatives. 2. To prioritize the molecules for synthesis using virtual screening techniques. 3. To synthesize the virtually predicted molecules via different synthetic schemes. 4. To characterize the synthesized molecules by spectroscopic analysis. 5. To evaluate the synthesized compounds for in vitro biological activity. METHODS: A series of new heteroaryl thiazolidine-4-one derivatives was designed and subjected to in silico prioritization using various virtual screening strategies. The prioritized thiazolidinone derivatives were synthesized and screened for their in vitro antitubercular, anticancer, antileishmanial and antibacterial (Staphylococcus aureus; Streptococcus pneumonia; Escherichia coli; Pseudomonas aeruginosa) activities. RESULTS: The compounds with electronegative substitutions exhibited positive antitubercular activity, the derivatives possessing a methyl substitution exhibited good inhibitory response against breast cancer cell line MCF-7 while the compounds possessing a hydrogen bond acceptor site like hydroxyl and methoxy substitution in their structures exhibited good in vitro antileishmanial activity. Some compounds exhibited potent activity against gram positive bacteria Pseudomonas aeruginosa as compared to the standards. CONCLUSION: The designed compounds exhibited good in vitro anti-infective potential which was in good agreement with the in silico predictions and they can be developed as important lead molecules for anti-infective and chemotherapeutic drug research.

First Synthesis for Bis-Spirothiazolidine Derivatives as a Novel Heterocyclic Framework and Their Biological Activity.

BACKGROUND: Spirothiazolidines are versatile synthetic scaffold possessing wide spectrum of biological interests involving potential anticancer activity. OBJECTIVE: To report the first synthesis of Bis Spiro-thiazolidine as a novel heterocyclic ring system. METHODS: One-pot three-component reaction including condensation of p-phenyllene diamine; cyclohexanone and thioglycolic acid produced Spiro-thiazolidine 4, which underwent further condensation with cyclohexanone and thioglycolic acid with equimolar ratio to introduce Bis-Spiothiazolidine 5 as the first synthesis. Also, bis spiro-thiazolidine arylidene derivatives 6-13 were synthesized by the reaction of Bis-Spiothiazolidine 5 with different aromatic benzaldehydes. RESULTS: Four compounds 13, 12, 9 and 11 have shown highly significant anticancer activity compared to Doxorubicin® (positive control) against Human liver carcinoma (HepG2) and Human Normal Retina pigmented epithelium (RPE-1) cell lines. CONCLUSION: The novel bis-spirothiazolidine deriviatives have been synthesized for the first time and showed excellent anticancer activities compare with the corresponding spirothiazolidine derivatives.

The Synthetic Dipeptide Pidotimod Shows a Chemokine-Like Activity through CXC Chemokine Receptor 3 (CXCR3).

In recent years immunomodulators have gained a strong interest and represent nowadays an active expanding area of research for the control of microbial diseases and for their therapeutic potential in preventing, treating and reducing the morbidity and mortality of different diseases. Pidotimod (3-L-pyroglutamyl-L-thiaziolidine-4carboxylic acid, PDT) is a synthetic dipeptide, which possesses immunomodulatory properties and exerts a well-defined pharmacological activity against infections, but its real mechanism of action is still undefined. Here, we show that PDT is capable of activating tyrosine phosphorylation-based cell signaling in human primary monocytes and triggering rapid adhesion and chemotaxis. PDT-induced monocyte migration requires the activation of the PI3K/Akt signaling pathway and chemokine receptor CXCR3. Indeed, a mAb to CXCR3 and a specific receptor inhibitor suppressed significantly PDT-dependent chemotaxis, and CXCR3-silenced primary monocytes lost responsiveness to PDT chemoattraction. Moreover, our results highlighted that the PDT-induced migratory activity is sustained by the CXCR3A isoform, since CXCR3-transfected L1.2 cells acquired responsiveness to PDT stimulation. Finally, we show that PDT, as CXCR3 ligands, is also able to direct the migration of IL-2 activated T cells, which express the highest levels of CXCR3 among CXCR3-expressing cells. In conclusion, our study defines a chemokine-like activity for PDT through CXCR3A and points on the possible role that this synthetic dipeptide may play in leukocyte trafficking and function. Since recent studies have highlighted diverse therapeutic roles for molecules which activates CXCR3, our findings call for an exploration of using this dipeptide in different pathological processes.

Anti-hepatitis-C virus activity and QSAR study of certain thiazolidinone and thiazolotriazine derivatives as potential NS5B polymerase inhibitors.

The present study reports on evaluation of anti-HCV activity and QSAR of certain arylidenethiazolidinone derivatives as potential inhibitors of HCV-NS5B polymerase. The pursued compounds involving, 5-aryliden-3-arylacetamidothiazolidin-2,4-diones 4-6(a-f), 5-arylidine-2-(N-arylacetamido)-iminothiazolidin-4-one (10) and their rigid counterparts 5-arylidinethiazolotriazines 13-15(a-f), were synthesized and their structures confirmed by spectral and elemental analyses. The results of NS5B polymerase inhibition assay revealed compound 4e, as the most active inhibitor (IC50 = 0.035 µM), which is four folds greater than that of the reference agent, VCH-759, (IC50 = 0.14 µM). Meanwhile, compounds 4b, 4c, 5a, and 5c, and 13b, 14e and 15c displayed equipotency to 2 folds higher activity than VCH-759 (IC50 values: 0.085, 0.14, 0.14, 0.10, 0.12, 0.09 and 0.07 µM, respectively). Assessment of the anti-HCV activity (GT1a) using human hepatoma cell line (Huh-7.5) illustrates superior activity of 4e (EC50 = 3.80 µM) relative to VCH-759 (EC50 = 5.29 µM). Cytotoxicity evaluation on, Transformed normal cell lines (Human Liver Epithelial-2, THLE-2 and Proximal Tubular Epithelial, RPTEC/TERT1), demonstrate enhanced safety profile of 4e (CC50 = 102.77, 161.37 µM, respectively) compared to VCH-759 (CC50 = 61.83, 81.28 µM, respectively). Molecular docking of the synthesized derivatives to NS5B polymerase allosteric site (PDB: 2HWH) showed similar binding modes to that of the co-crystallized ligand. Moreover, QSAR models were established for the studied thiazolidinones and thiazolotriazines to investigate the molecular characteristics contributing to the observed NS5B polymerase inhibition activity. The obtained results inspire further investigations of thiazolidinones and thiazolotriazine aiming at affording more potent, safe and orally active non-nucleoside NS5B polymerase inhibitors as anti-HCV drug candidates.

Novel thiazolidines: Synthesis, antiproliferative properties and 2D-QSAR studies.

A series of N-substituted (Z)-2-imino-(5Z)-ylidene thiazolidines/thiazolidin-4-ones were synthesized and their antiproliferative activities against colon (HCT-116) and breast (MCF7) cancer cell lines were evaluated utilizing an MTT growth assay. A 2D-QSAR investigation was conducted to probe and validate the obtained antiproliferative properties for the thiazolidine derivatives. The majority of the thiazolidines exhibit higher potency against a colon cancer cell line relative to the standard reference. The p-halophenylimino p-anisylidene derivatives exhibited the highest anti-proliferative activity against HCT116 relative to control (IC50 = 8.9-10.0 µM compared to 20.4 µM observed for 5-fluorouracil as positive control). An X-ray study confirmed the Z, Z'-configurations for two examples of the synthesized compounds.

Synthesis and biological evaluation of indole-2-carbohydrazides and thiazolidinyl-indole-2-carboxamides as potent tubulin polymerization inhibitors.

A new series of N'-(substituted phenyl)-5-chloro/iodo-3-phenyl-1H-indole-2-carbohydrazide (5, 6) and N-[2-(substituted phenyl)-4-oxo-1,3-thiazolidin-3-yl]-5-iodo/chloro-3-phenyl-1H-indole-2-carboxamide (7, 8) derivatives were synthesized and evaluated for their anticancer properties. Compounds 5a and 6b, selected as prototypes by the National Cancer Institute for screening against the full panel of 60 human tumor cell lines at a minimum of five concentrations at 10-fold dilutions, demonstrated remarkable antiproliferative activity against leukemia, non-small cell lung cancer, colon cancer, central nervous system (CNS) cancer, melanoma, ovarian cancer, renal cancer, and breast cancer (MCF-7) cell lines with GI50 values < 0.4 µM. A subset of the compounds was then tested for their potential to inhibit tubulin polymerization. Compounds 6f and 6g showed significant cytotoxicity at the nM level on MCF-7 cells and exhibited significant inhibitory activity on tubulin assembly and colchicine binding at about the same level as combretastatin A-4. Finally, docking calculations were performed to identify the binding mode of these compounds. Group 5 and 6 compounds interacted with the colchicine binding site through hydrophobic interactions similar to those of colchicine. These compounds with antiproliferative activity at high nanomolar concentration can serve as scaffolds for the design of novel microtubule targeting agents.