Synthesis and in vitro antitumor evaluation of some indeno[1,2-c]pyrazol(in)es substituted with sulfonamide, sulfonylurea(-thiourea) pharmacophores, and some derived thiazole ring systems

Derivatization of Abietane Acids by Peptide-like Substituents Leads to Submicromolar Cytotoxicity at NCI-60 Panel

Natural compounds, including diterpenoids, play a critical role in various biological processes and are recognized as valuable components in cancer treatment. Isocyanides multicomponent reactions (IsMCRs) are one of the effective methods to obtain adducts at the carboxyl group with a peptide-like substituent. In this study, dehydroabietic acid and levopimaric acid diene adducts as the starting scaffolds were modified by the multicomponent Passerini (P-3CR) and Ugi (U-4CR) reactions to afford α-acyloxycarboxamides and α-acylaminocarboxamides. A group of twenty novel diterpene hybrids was subjected to NCI in vitro assessment, and a consistent structure-activity relationship was established. Eleven of the synthesized derivatives inhibited the growth of cancer cells of 4 to 39 cell lines in one dose assay, and the most active were derivatives 3d, 9d, and 10d holding a fragment of 1a,4a-dehydroquinopimaric acid. They were selected for a five-dose analysis and demonstrated a significant antiproliferative effect towards human cancer cell lines. The outstanding cytotoxic activity was observed for the P-3CR product 3d with growth inhibitory at submicromolar and micromolar concentrations (GI50 = 0.42-3 μM) against the most sensitive cell lines. The U-4CR products 9d and 10d showed selective activity against all leukemia cell lines with GI50 in the range of 1-17 µM and selectivity indexes of 5.49 and 4.72, respectively. Matrix COMPARE analysis using the GI50 vector showed a moderate positive correlation of compound 3d with standard anticancer agents that can influence kinase receptors and epidermal growth factor receptors (EGFRs). The ADMET analysis acknowledges the favorable prognosis using compounds as potential anticancer agents. The obtained results indicate that these new hybrids could be useful for the further development of anticancer drugs, and 1a,4a-dehydroquinopimaric acid derivatives could be recommended for in-depth studies and the synthesis of new antitumor analogs on their basis.

Anticancer Drug Discovery By Structure-Based Repositioning Approach

Despite the tremendous progress that has occurred in recent years in cell biology and oncology, in chemical, physical and computer sciences, the disease cancer has continued as the major cause of death globally. Research organizations, academic institutions and pharmaceutical companies invest huge amounts of money in the discovery and development of new anticancer drugs. Though much effort is continuing and whatever available approaches are being attempted, the success of bringing one effective drug into the market has been uncertain. To overcome problems associated with drug discovery, several approaches are being attempted. One such approach has been the use of known, approved and marketed drugs to screen these for new indications, which have gained considerable interest. This approach is known in different terms as "drug repositioning or drug repurposing." Drug repositioning refers to the structure modification of the active molecule by synthesis, in vitro/ in vivo screening and in silico computational applications where macromolecular structure-based drug design (SBDD) is employed. In this perspective, we aimed to focus on the application of repositioning or repurposing of essential drug moieties present in drugs that are already used for the treatment of some diseases such as diabetes, human immunodeficiency virus (HIV) infection and inflammation as anticancer agents. This review thus covers the available literature where molecular modeling of drugs/enzyme inhibitors through SBDD is reported for antidiabetics, anti-HIV and inflammatory diseases, which are structurally modified and screened for anticancer activity using respective cell lines.

Synthesis, molecular docking and anti-inflammatory evaluation of new trisubstituted pyrazoline derivatives bearing benzenesulfonamide moiety

A new series of trisubstituted pyrazoline bearing benzenesulfonamide moiety 6a,b-10a,b were designed, synthesised and evaluated for their anti-inflammatory in vitro. Before starting the synthesis, docking study has been used to insert compounds within the COX-2 structure active site using celecoxib drug as a reference. Final compounds 6a,b-10a,b were synthesised by condensing chalcones bearing pyridine moiety 1a,b-5a,b with 4-hydrazinyl benzenesulfonamide hydrochloride. In vitro, their anti-inflammatory activity was assessed using egg-white paw edema method, they showed moderate to strong inhibitory activity. Notably, Compounds 6a (29.78%), 7a (28.43%), 9a (27.92%) and 10a (27.92%) exhibited significant percentage inhibition at 300 min and results are comparable with percentage inhibition drug celecoxib (22.67%) and this result is highly agreement with docking scoring study.

Recent advances in synthetic strategies and SAR of thiazolidin-4-one containing molecules in cancer therapeutics

Cancer is one of the life-threatening diseases accountable for millions of demises globally. The inadequate effectiveness of the existing chemotherapy and its harmful effects has resulted in the necessity of developing innovative anticancer agents. Thiazolidin-4-one scaffold is among the most important chemical skeletons that illustrate anticancer activity. Thiazolidin-4-one derivatives have been the subject of extensive research and current scientific literature reveals that these compounds have shown significant anticancer activities. This manuscript is an earnest attempt to review novel thiazolidin-4-one derivatives demonstrating considerable potential as anticancer agents along with a brief discussion of medicinal chemistry-related aspects of these compounds and structural activity relationship studies in order to develop possible multi-target enzyme inhibitors. Most recently, various synthetic strategies have been developed by researchers to get various thiazolidin-4-one derivatives. In this review, the authors highlight the various synthetic, green, and nanomaterial-based synthesis routes of thiazolidin-4-ones as well as their role in anticancer activity by inhibition of various enzymes and cell lines. The detailed description of the existing modern standards in the field presented in this article may be interesting and beneficial to the scientists for further exploration of these heterocyclic compounds as possible anticancer agents.

Design, synthesis, and biological evaluation with molecular dynamics study of novel pyrazolo[3,4-d]pyrimidine derivatives as anti-cancer agents

In continuation of our efforts to discover new structural chemotypes with significant chemotherapeutic activities, a novel series of pyrazolo[3,4-d]pyrimidine-based compounds linked to a piperazine ring, bearing different aromatic moieties, through different linkages was designed and synthesized as FLT3 inhibitors. All of the newly synthesized compounds were evaluated for their cytotoxicity on 60-NCI cell lines. Compounds with the piperazine acetamide linkage XIIa-f & XVI exhibited a remarkable anticancer activity among all of the tested compounds, especially against non-small cell lung cancer, melanoma, leukemia and renal cancer models. Furthermore, compound XVI (NSC no - 833644) was further screened with a 5-dose assay on nine subpanels and exhibited a GI₅₀ between 1.17 and 18.40 μM. On the other hand, molecular docking and dynamics studies were performed to predict the binding mode of the newly synthesized compounds in the FLT3 binding domain. Finally, through a predictive kinetic study, several ADME descriptors were calculated.

Novel pyrimido-pyridazine derivatives: design, synthesis, anticancer evaluation and in silico studies

Aim: A novel pyrimido-pyridazine derivative for developing anticancer agents was synthesized via Ullmann arylation using an efficient Cu(OAc)₂ catalyst. Materials & methods: Compounds were investigated for their anticancer potential, against human breast adenocarcinoma cells, viz. MCF-7, MDA-MB-231 and normal cell line HEK-293. Further, an in vivo study was conducted on lymphoma-bearing mice while in silico analysis was carried out for molecular interactions. Results: Compound 2b displayed significant antitumor activity towards MDA-MB-231 cells through induction of apoptosis and arresting cells in S-phase in vitro, while it significantly increased the lifespan and reduced tumor growth in vivo. An in silico study revealed potent tyrosine-protein kinase inhibitors. Conclusion: Taken together the molecule has the potential to become an effective therapeutic treatment for breast cancer.

Synthesis, DFT Analyses, Antiproliferative Activity, and Molecular Docking Studies of Curcumin Analogues

With 19.3 million new cases and almost 10 million deaths in 2020, cancer has become a leading cause of death today. Curcumin and its analogues were found to have promising anticancer activity. Inspired by curcumin’s promising anticancer activity, we prepared three semi-synthetic analogues by chemically modifying the diketone function of curcumin to its pyrazole counterpart. The curcumin analogues (3a−c) were synthesized by two different methods, followed by their DFT analyses to study the HOMO/LUMO configuration to access the stability of compounds (∆E = 3.55 to 3.35 eV). The curcumin analogues (3a−c) were tested for antiproliferative activity against a total of five dozen cancer cell lines in a single (10 µM) and five dose (0.001 to 100 µM) assays. 3,5-Bis(4-hydroxy-3-methoxystyryl)-1H-pyrazole-1-yl-(phenoxy)ethanone (3b) and 3,5-bis(4-hydroxy-3-methoxystyryl)-1H-pyrazole-1-yl-(2,4-dichlorophenoxy)ethanone (3c) demonstrated the most promising antiproliferative activity against the cancer cell lines with growth inhibitions of 92.41% and 87.28%, respectively, in a high single dose of 10 µM and exhibited good antiproliferative activity (%GIs > 68%) against 54 out of 56 cancer cell lines and 54 out of 60 cell lines, respectively. The compound 3b and 3c demonstrated the most potent antiproliferative activity in a 5-dose assay with GI50 values ranging between 0.281 and 5.59 µM and 0.39 and 0.196 and 3.07 µM, respectively. The compound 3b demonstrated moderate selectivity against a leukemia panel with a selectivity ratio of 4.59. The HOMO-LUMO energy-gap (∆E) of the compounds in the order of 3a > 3b > 3c, was found to be in harmony with the anticancer activity in the order of 3c ≥ 3b > 3a. Following that, all of the curcumin analogues were molecular docked against EGFR, one of the most appealing targets for antiproliferative activity. In a molecular docking simulation, the ligand 3b exhibited three different types of interactions: H-bond, π-π-stacking and π-cationic. The ligand 3b displayed three H-bonds with the residues Met793 (with methoxy group), Lys875 (with phenolic group) and Asp855 (with methoxy group). The π-π-stacking interaction was observed between the phenyl (of phenoxy) and the residue Phe997, while π-cationic interaction was displayed between the phenyl (of curcumin) and the residue Arg841. Similarly, the ligand 3c displayed five H-bonds with the residue Met793 (with methoxy and phenolic groups), Lys845 (methoxy group), Cys797 (phenoxy oxygen), and Asp855 (phenolic group), as well as a halogen bond with residue Cys797 (chloro group). Furthermore, all the compound 3a−c demonstrated significant binding affinity (−6.003 to −7.957 kcal/mol) against the active site of EGFR. The curcumin analogues described in the current work might offer beneficial therapeutic intervention for the treatment and prevention of cancer. Future anticancer drug discovery programs can be expedited by further modifying these analogues to create new compounds with powerful anticancer potentials.

Development of Novel Pyridine-Thiazole Hybrid Molecules as Potential Anticancer Agents

Novel pyridine-thiazole hybrid molecules were synthesized and subjected to physico-chemical characterization and screening of their cytotoxic action towards a panel of cell lines derived from different types of tumors (carcinomas of colon, breast, and lung, glioblastoma and leukemia), and normal human keratinocytes, for comparison. High antiproliferative activity of the 3-(2-fluorophenyl)-1-[4-methyl-2-(pyridin-2-ylamino)-thiazol-5-yl]-propenone 3 and 4-(2-{1-(2-fluorophenyl)-3-[4-methyl-2-(pyridin-2-ylamino)-thiazol-5-yl]-3-oxopropylsulfanyl}-acetylamino)-benzoic acid ethyl ester 4 was revealed. The IC50 of the compound 3 in HL-60 cells of the acute human promyelocytic leukemia was 0.57 µM, while in the pseudo-normal human cell lines, the IC50 of this compound was >50 µM, which suggests that the compounds 3 and 4 might be perspective anticancer agents. The detected selectivity of the derivatives 3 and 4 for cancer cell lines inspired us to study the mechanisms of their cytotoxic action. It was shown that preincubation of tumor cells with Fluzaparib (inhibitor of PARP1) reduced the cytotoxic activity of the derivatives 3 and 4 by more than twice. The ability of these compounds to affect DNA nativity and cause changes in nucleus morphology allows for the suggestion that the mechanism of action of the novel pyridine-thiazole derivatives might be related to inducing the genetic instability in tumor cells.

Highly bioactive novel aryl-, benzyl-, and piperazine-selenoureas: synthesis, structural characterization and in vitro biological evaluation

Selenoureas are widespread as useful elements for constructing important species and biologically active molecules. Finding an efficient and straightforward method to prepare this motif and biologically screen derivatives thereof is crucial. Herein, we demonstrate the effectiveness of using ethanol as a solvent in the preparation of various substituted aryl-, benzyl-, and piperazine-selenoureas from isoselenocyanates and amines. The synthetic method includes mild reaction conditions, large substrate scope, and good isolated yields. Biological evaluation of the prepared products on MDA-MB-231 and MCF-7 cancer cell lines revealed several remarkably active compounds (IC₅₀ < 10 μΜ) with the best one exhibiting IC₅₀ values of 1.8 μΜ and 1.2 μΜ observed against the challenging former triple-negative breast cancer cell line and the latter one, respectively. The chemical structures of all new compounds were fully characterized by multinuclear nuclear magnetic resonance (NMR) spectroscopy and high accuracy mass measurements.

Synthesis, biological evaluation, migratory inhibition and docking study of Indenopyrazolones as potential anticancer agents

Some bioactive derivatives of indeno[1,2- c ]pyrazolones were synthesized through the reaction of phenylhydrazine, different aldehydes and indan-1,2,3-trione at room temperature in acetonitrile. Analytical and spectroscopic studies have confirmed the structural characteristics of the synthesized compounds. In addition, the target compounds were screened for the in-vitro antiproliferative properties against the B16F10 melanoma cancer cell line by the standard MTT assay. The effect on inflammatory marker cyclooxygenase 2 and matrix metalloproteinase 2, 9 was also checked to determine the anti-inflammatory and anti-cell migratory properties of these compounds. The final compounds were also tested for their tyrosinase inhibitory activity. Among all compounds, screened for anticancer activity, three compounds 4e , 4f and 4h reduced the cell proliferation significantly comparable to that of the positive standard drug erlotinib (IC 50 = 418.9±1.54 µM) with IC 50 values ranging from 20.72-29.35 µM. The compounds 4c-4h decreased the COX-2 expression whereas the MMP 2, 9 expressions were significantly reduced by 4a , 4b and 4h . This was confirmed by molecular docking studies, as 4e , 4f and 4h displayed good interactions with the active site of BRAF protein. The compounds 4b , 4f and 4h exhibited moderate tyrosinase inhibition effect as compared to α-MSH. Collectively, compound 4h can be considered as a candidate for further optimization in the development of anticancer therapies based on the results of biological investigations in this study.

Hollongdione arylidene derivatives induce antiproliferative activity against melanoma and breast cancer through pro-apoptotic and antiangiogenic mechanisms

The use of natural compounds as starting point for semisynthetic derivatives has already been proven as a valuable source of active anticancer agents. Hollongdione (4,4,8,14-tetramethyl-18-norpregnan-3,20-dion), obtained by few steps from dammarane type triterpenoid dipterocarpol, was chemically modified at C2 and C21 carbon atoms by the Claisen-Schmidt aldol condensation to give a series of arylidene derivatives. The anticancer activity of the obtained compounds was assessed on NCI-60 cancer cell panel, revealing strong antiproliferative effects against a large variety of cancer cells. 2,21-Bis-[3-pyridinyl]-methylidenohollongdione 9 emerged as the most active derivative as indicated by its GI₅₀ values in the micromolar range which, combined with its high selectivity index values, indicated its suitability for deeper biological investigation. The mechanisms involved in compound 9 antiproliferative activity, were investigated through in vitro (DAPI staining) and ex vivo (CAM assay) tests, which exhibited its apoptotic and antiangiogenic activities. In addition, compound 9 showed an overall inhibition of mitochondrial respiration. rtPCR analysis identified the more intimate activity at pro-survival/pro-apoptotic gene level. Collectively, the hollongdione derivative stand as a promising therapeutic option against melanoma and breast cancer provided that future in vivo analysis will certify its clinical efficacy.

Novel Synthesized N-Ethyl-Piperazinyl-Amides of C2-Substituted Oleanonic and Ursonic Acids Exhibit Cytotoxic Effects through Apoptotic Cell Death Regulation

A series of novel hybrid chalcone N-ethyl-piperazinyl amide derivatives of oleanonic and ursonic acids were synthesized, and their cytotoxic potential was evaluated in vitro against the NCI-60 cancer cell line panel. Compounds 4 and 6 exhibited the highest overall anticancer activity, with GI₅₀ values in some cases reaching nanomolar values. Thus, the two compounds were further assessed in detail in order to identify a possible apoptosis- and antiangiogenic-based mechanism of action induced by the assessed compounds. DAPI staining revealed that both compounds induced nuclei condensation and overall cell morphological changes consistent with apoptotic cell death. rtPCR analysis showed that up-regulation of pro-apoptotic Bak gene combined with the down-regulation of the pro-survival Bcl-XL and Bcl-2 genes caused altered ratios between the pro-apoptotic and anti-apoptotic proteins’ levels, leading to overall induced apoptosis. Molecular docking analysis revealed that both compounds exhibited high scores for Bcl-XL inhibition, suggesting that compounds may induce apoptotic cell death through targeted anti-apoptotic protein inhibition, as well. Ex vivo determinations showed that both compounds did not significantly alter the angiogenesis process on the tested cell lines.

Molecular Engineering of Curcumin, an Active Constituent of Curcuma longa L. (Turmeric) of the Family Zingiberaceae with Improved Antiproliferative Activity

Cancer is the world’s second leading cause of death, accounting for nearly 10 million deaths and 19.3 million new cases in 2020. Curcumin analogs are gaining popularity as anticancer agents currently. We reported herein the isolation, molecular engineering, molecular docking, antiproliferative, and anti-epidermal growth factor receptor (anti-EGFR) activities of curcumin analogs. Three curcumin analogs were prepared and docked against the epidermal growth factor receptor (EGFR), revealing efficient binding. Antiproliferative activity against 60 NCI cancer cell lines was assessed using National Cancer Institute (NCI US) protocols. The compound 3b,c demonstrated promising antiproliferative activity in single dose (at 10 µM) as well as five dose (0.01, 0.10, 1.00, 10, and 100 µM). Compound 3c inhibited leukemia cancer panel better than other cancer panels with growth inhibition of 50% (GI₅₀) values ranging from 1.48 to 2.73 µM, and the most promising inhibition with GI₅₀ of 1.25 µM was observed against leukemia cell line SR, while the least inhibition was found against non-small lung cancer cell line NCI-H226 with GI₅₀ value of 7.29 µM. Compounds 3b,c demonstrated superior antiproliferative activity than curcumin and gefitinib. In molecular docking, compound 3c had the most significant interaction with four H-bonds and three π–π stacking, and compound 3c was found to moderately inhibit EGFR. The curcumin analogs discovered in this study have the potential to accelerate the anticancer drug discovery program.

Thiazole Ring-A Biologically Active Scaffold

BACKGROUND

Thiazole is a good pharmacophore nucleus due to its various pharmaceutical applications. Its derivatives have a wide range of biological activities such as antioxidant, analgesic, and antimicrobial including antibacterial, antifungal, antimalarial, anticancer, antiallergic, antihypertensive, anti-inflammatory, and antipsychotic. Indeed, the thiazole scaffold is contained in more than 18 FDA-approved drugs as well as in numerous experimental drugs.

OBJECTIVE

To summarize recent literature on the biological activities of thiazole ring-containing compounds Methods: A literature survey regarding the topics from the year 2015 up to now was carried out. Older publications were not included, since they were previously analyzed in available peer reviews.

RESULTS

Nearly 124 research articles were found, critically analyzed, and arranged regarding the synthesis and biological activities of thiazoles derivatives in the last 5 years.

Synthesis and Anticancer Activity Evaluation of 5-[2-Chloro-3-(4-nitrophenyl)-2-propenylidene]-4-thiazolidinones

A series of novel 5-[(Z,2Z)-2-chloro-3-(4-nitrophenyl)-2-propenylidene]-thiazolidinones (Ciminalum-thiazolidinone hybrid molecules) have been synthesized. Anticancer activity screening toward the NCI60 cell lines panel, gastric cancer (AGS), human colon cancer (DLD-1), and breast cancer (MCF-7 and MDA-MB-231) cell lines allowed the identification of 3-{5-[(Z,2Z)-2-chloro-3-(4-nitrophenyl)-2-propenylidene]-4-oxo-2-thioxothiazolidin-3-yl}propanoic acid (2h) with the highest level of antimitotic activity with mean GI₅₀/TGI values of 1.57/13.3 μM and a certain sensitivity profile against leukemia (MOLT-4, SR), colon cancer (SW-620), CNS cancer (SF-539), melanoma (SK-MEL-5), gastric cancer (AGS), human colon cancer (DLD-1), and breast cancers (MCF-7 and MDA-MB-231) cell lines. The hit compounds 2f, 2i, 2j, and 2h have been found to have low toxicity toward normal human blood lymphocytes and a fairly wide therapeutic range. The significant role of the 2-chloro-3-(4-nitrophenyl)prop-2-enylidene (Ciminalum) substituent in the 5 position and the substituent's nature in the position 3 of core heterocycle in the anticancer cytotoxicity levels of 4-thiazolidinone derivatives have been established.

6-Morpholino- and 6-amino-9-sulfonylpurine derivatives. Synthesis, computational analysis, and biological activity

The synthesis of novel 6-chloro/morpholino/amino/-9-sulfonylpurine derivatives was accomplished in two ways, either (i) involving the condensation reaction of 6-chloropurine with commercially available arylsulfonyl chlorides in acetone and the presence of aqueous KOH at 0 °C, followed by the substitution of C6-chlorine with morpholine, or (ii) employing a reversed synthetic approach where 6-morpholinopurine and commercially available adenine bases were reacted with the corresponding alkyl, 2-arylethene and arylsulfonyl chlorides giving the N9 sulfonylated products, the latter particularly used where prior nonselective sulfonylation was observed. In both approaches, the sulfonylation reaction occurred regioselectively at the purine N9 position lacking any concurrent N7 derivatives, except in the case of a smaller methyl substituent on SO₂ and the free amino group at C6 of the purine ring. The tautomeric features of initial N9 unsubstituted purines, as well as stability trends among the prepared N-9-sulfonylpurine derivates, were investigated using DFT calculations with an important conclusion that electron-donating C6 substituents are beneficial for the synthesis as they both promote the predominance of the desired N9 tautomers and help to assure the stability of the final products. The newly synthesized 6-morpholino and 6-amino-9-sulfonylpurine derivatives showed antiproliferative activity on human carcinoma, lymphoma, and leukemia cells. Among the tested compounds, 6-morpholino 17 and 6-amino 22 derivatives, with trans-β-styrenesulfonyl group attached at the N9 position of purine, proved to be the most effective antiproliferative agents, causing accumulation of leukemia cells in subG0 cell cycle phase.

Isoleucine with secondary sulfonamide functionality as anticancer, antibacterial and antifungal agents

Isoleucine substituted analogues with secondary sulfonamide group (I₁-I₆) have been synthesized. Structures of synthesized analogues have been confirmed by Fourier Transform-Infrared Red, Nuclear Magnetic Resonance (¹H and ¹³C) and ESI-MS spectroscopic tools. Cytotoxic screenings of synthesized analogues have been done on MCF-7 (breast), Prostate Cancer-3 (PC-3) and A549 (lung) cancer cell lines. N-(1-isobutyl-2-oxo-2-anilinoethyl) p-toluene sulfonamide (I₅) screened to be better cytotoxic agent on MCF-7 and A549 cell lines whereas N-(1-isobutyl-2-oxo-2-p-chloroanilino ethyl) benzene sulfonamide (I₃) against PC-3 cell line. Cell cycle analysis of N-(1-isobutyl-2-oxo-2-anilinoethyl) p-toluene sulfonamide (I₅) analogue has been carried out on A549 cell line in comparison to control and Vinblastine (standard drug). Complete arrest in G0 and G1 phase along with mild disturbance in S-phase of cell cycle has been observed. The screened analogues (I₁-I₆) also showed good antifungal and antibacterial potential against gram positive as well as gram negative strains. Computer simulation indicated good bioactivity prediction by the 'Lipinski rule' and synthesized analogues did not violate this rule. Docking study of isoleucine sulfonamide analogues (I₁-I₆) were carried out to determine the possible interaction sites of the analogues with p53 tumor suppressor-DNA complex and demonstrate that the analogues confirmed binding and inhibition with the most mutated residues of p53. Density functional theory has been used to correlate the electronic and chemical properties of analogues and they were found to be stable and chemically reactive. Thus the results suggest that isoleucine substituted sulfonamide analogues can serve as a structural model for the design of anticancer agents, antibacterial agents as well as antifungal agents with better inhibitory potential.Communicated by Ramaswamy H. Sarma.

Cytotoxic Potential of a-Azepano- and 3-Amino-3,4-SeCo-Triterpenoids

Semi-synthetic triterpenoids, holding an amino substituted seven-membered A-ring (azepano-ring), which could be synthesized from triterpenic oximes through a Beckmann type rearrangement followed by a reduction of lactame fragment, are considered to be novel promising agents exhibiting anti-microbial, alpha-glucosidase, and butyrylcholinesterase inhibitory activities. In this study, in an attempt to develop new antitumor candidates, a series of A-ring azepano- and 3-amino-3,4-seco-derivatives of betulin, oleanolic, ursolic, and glycyrrhetinic acids were evaluated for their cytotoxic activity against five human cancer cell lines and non-malignant mouse fibroblasts by means of a colorimetric sulforhodamine assay. Azepanoallobetulinic acid amide derivative 11 was the most cytotoxic compound of this series but showed little selectivity between the different human tumor cell lines. Flow cytometry experiments showed compound 11 to act mainly by apoptosis (44.3%) and late apoptosis (21.4%). The compounds were further screened at the National Cancer Institute towards a panel of 60 cancer cell lines. It was found that compounds 3, 4, 7, 8, 9, 11, 15, 16, 19, and 20 showed growth inhibitory (GI₅₀) against the most sensitive cell lines at submicromolar concentrations (0.20–0.94 μM), and their cytotoxic activity (LC₅₀) was also high (1–6 μM). Derivatives 3, 8, 11, 15, and 16 demonstrated a certain selectivity profile at GI₅₀ level from 5.16 to 9.56 towards K-562, CCRF-CEM, HL-60(TB), and RPMI-8226 (Leukemia), HT29 (Colon cancer), and OVCAR-4 (Ovarian cancer) cell lines. Selectivity indexes of azepanoerythrodiol 3 at TGI level ranged from 5.93 (CNS cancer cell lines SF-539, SNB-19 and SNB-75) to 14.89 for HCT-116 (colon cancer) with SI 9.56 at GI₅₀ level for the leukemia cell line K-562. The present study highlighted the importance of A-azepano-ring in the triterpenic core for the development of novel antitumor agents, and a future aim to increase the selectivity profile will thus lie in the area of modifications of azepano-triterpenic acids at their carboxyl group.

Recent Progress of Benzimidazole Hybrids for Anticancer Potential

This review presents the detailed account of factors leading to cancer and design strategy for the synthesis of benzimidazole derivatives as anticancer agents. The recent survey for cancer treatment in Cancer facts and figures 2017 American Chemical Society has shown progressive development in fighting cancer. Researchers all over the world in both developed and developing countries are in a continuous effort to tackle this serious concern. Benzimidazole and its derivatives showed a broad range of biological activities due to their resemblance with naturally occurring nitrogenous base i.e. purine. The review discussed benzimidazole derivatives showing anticancer properties through a different mechanism viz. intercalation, alkylating agents, topoisomerases, DHFR enzymes, and tubulin inhibitors. Benzimidazole derivatives act through a different mechanism and the substituents reported from the earlier and recent research articles are prerequisites for the synthesis of targeted based benzimidazole derivatives as anticancer agents. The review focuses on an easy comparison of the substituent essential for potency and selectivity through SAR presented in figures. This will further provide a better outlook or fulfills the challenges faced in the development of novel benzimidazole derivatives as anticancer.

Novel Mannich bases of ciprofloxacin with improved physicochemical properties, antibacterial, anticancer activities and caspase-3 mediated apoptosis

The design, synthesis and identification of a novel series of Mannich bases of ciprofloxacin was reported. Naphthol derivatives 2a and 2b showed highly potent cytotoxic activity among the tested compounds. Compound 2a showed broad spectrum antiproliferative activity with GI₅₀ of 2.5-6.79 µM with remarkable selectivity towards renal and prostate cancers with selectivity ratios ranging from 0.17 to 6.79. Independently, 2a showed outstanding activity against colon cancer HOP-92 cell lines with IC₅₀ of 6.66 µM while 2b showed highly potent activity against ovarian cancer cell lines with IC₅₀ of 0.97 µM. Results showed that 2b induced cell cycle arrest at G2/M phase and apoptosis; compound 2b showed over-expression of caspase-3 protein level (449.2 ± 7.95) compared to doxorubicin (578.7 ± 14.4 pg/mL). Meanwhile, compounds 2a and 2b experienced outstanding activity against both Gram-positive and Gram-negative microorganisms. Interestingly, compound 2j experienced high activity against Escherichia coli and Pseudomonas aeruginosa with MIC of 0.036 and 0.043, respectively. Compound 2d revealed 27 folds and 22 folds, respectively increasing of activity over ciprofloxacin against Staphylococcus aureus and MRSA(reference strain). Compound 2d showed high activity against Staphylococcus aureus, MRSA (reference strain) and MRSA (clinical strain) with MIC of 0.57, 0.52, 0.082 µg/mL, respectively. Interestingly, the most active tested compounds were found to have promising physicochemical and drug likeness properties. The Mannich bases 2j, 2d and 2g showed promising antibacterial activities, while naphthols 2a and 2b showed promising antiproliferative and antibacterial activities that require further optimization.

Design and synthesis of novel pyrazolo[3,4-d]pyrimidin-4-one bearing quinoline scaffold as potent dual PDE5 inhibitors and apoptotic inducers for cancer therapy

PDE5 targeting represents a new and promising strategy for apoptosis induction and inhibition of tumor cell growth due to its over-expression in diverse types of human carcinomas. Accordingly, we report the synthesis of series of pyrazolo[3,4-d]pyrimidin-4-one carrying quinoline moiety (11a-r) with potential dual PDE5 inhibition and apoptotic induction for cancer treatment. These hybrids were structurally elucidated and characterized with variant spectroscopic techniques as ¹H NMR, ¹³C NMR and elemental analysis. The assessment of their anticancer activities has been declared. All the rationalized compounds 11a-r have been selected for their cytotoxic activity screening by NCI against 60 cell lines. Compounds 11a, 11b, 11j and 11k were the most active hybrids. Among all, compound 11j was further selected for five dose tesing and it displayed outstanding activity with strong antitumor activity against the nine tumor subpanels tested with selectivity ratios ranging from 0.019 to 8.3 at the GI₅₀ level. Further, the most active targets 11a, b, j and k were screened for their PDE5 inhibitory activity, compound 11j (with IC₅₀ 1.57 nM) exhibited the most potent PDE5 inhibitory activity. Moreover, compound 11j is also showed moderate EGFR inhibition with IC₅₀ of 5.827 ± 0.46 µM, but significantly inhibited the Wnt/β-catenin pathway with IC₅₀1286.96 ± 12.37 ng/mL. In addition, compound 11j induced the intrinsic apoptotic mitochondrial pathway in HepG2 cells as evidenced by the lower expression levels of the anti-apoptotic Bcl-2 protein, and the higher expression of the pro-apoptotic protein Bax, p53, cytochrome c and the up-regulated active caspase-9 and caspase-3 levels. All results confirmed by western blotting assay. Compound 11j exhibit pre G1 apoptosis and cell cycle arrest at G2/M phase. In conclusion, hybridization of quinoline moiety with the privileged pyrazolo[3,4-d]pyrimidinon-4-one structure resulted in highly potent anticancer agent, 11j, which deserves more study, in particular, in vivo and clinical investiagtions, and it is expected that these results would be applied for more drug discovery process.

Versatile mechanisms of 2-substituted benzimidazoles in targeted cancer therapy

Background

The aim of this review is to provide an overview on diverse anticancer activities of 2-substituted benzimidazole derivatives.

Main body

This review provides a correlation between the various mechanisms of action of benzimidazoles as anticancer and the substitution pattern around the nucleus.

Conclusion

The linker group and substitution at N-1, C-2, C-5, and C-6 positions have been found to be the most contributory factors for anticancer activity. This will help in the further design to afford more selective, potent, and multi-target anticancer of 2-substituted benzimidazole-based compounds.

Design and synthesis of new 1,6-dihydropyrimidin-2-thio derivatives targeting VEGFR-2: Molecular docking and antiproliferative evaluation

A series of new 1,6-dihydropyrimidin-2-thiol derivatives (scaffold A) as VEGFR-2 inhibitors has been designed and synthesized. Compounds 3a, 3b, 3e and 4b have been selected for in vitro anticancer screening by the National Cancer Institute. Compound 3e showed remarkable anticancer activity against most of the cell lines tested, where a complete cell death against leukemia, non-small cell lung cancer, colon, CNS, melanoma, and breast cancer cell lines was observed. In vitro five dose tests showed that compound 3e had high activity against most of the tested cell lines with GI₅₀ ranging from 19 to 100 μM and selectivity ratios ranging between 0.75 and 1.71 at the GI₅₀ level. VEGFR-2-kinase was tested against 3a, 3b, 3e, 4b and sorafenib was used as a reference. Compounds 3a and 3e were the most potent analogues with IC₅₀ values of 386.4 nM and 198.7 nM against VEGFR-2, respectively, in comparison to sorafenib (IC₅₀ = 0.17 nM). The results of the docking study showed a good fitting of the new compounds to the active site of VEGFR-2 with binding free energies in the range of -9.80 to -11.25 kcal/mol compared to -12.12 kcal/mol for sorafenib. Compounds 4a-e with the hydroxyimino group had a higher affinity to VEGFR-2 than their parent derivatives 3a-e.

New Paracyclophanylthiazoles with Anti-Leukemia Activity: Design, Synthesis, Molecular Docking, and Mechanistic Studies

A new series of methyl 2-(2-(4′-[2.2]paracyclophanyl)-hydrazinylidene)-3-substituted-4-oxothiazolidin-5-ylidene)acetates 3a–f were synthesized from the reaction of paracyclophanyl-acylthiosemicarbazides 2a–f with dimethyl acetylenedicarboxylate. Based upon nuclear magnetic resonance (NMR), infrared (IR), and mass spectra (HRMS), the structure of the obtained products was elucidated. X-ray structure analysis was also used as unambiguous tool to elucidate the structure of the products. The target compounds 3a–f were screened against 60 cancer cell lines. They displayed anticancer activity against a leukemia subpanel, namely, RPMI-8226 and SR cell lines. The activity of compound 3a was found as the most cytotoxic potency against 60 cancer cell lines. Consequently, it was selected for further five doses analysis according to National Cancer Institute (NCI) protocol. The cytotoxic effect showed selectivity ratios ranging between 0.63 and 1.28 and between 0.58 and 5.89 at the GI₅₀ and total growth inhibition (TGI) levels, respectively. Accordingly, compound 3a underwent further mechanistic study against the most sensitive leukemia RPMI-8226 and SR cell lines. It showed antiproliferation with IC50 = 1.61 ± 0.04 and 1.11 ± 0.03 µM against RPMI-8226 and SR cell lines, respectively. It also revealed a remarkable tubulin inhibitory activity, compared to colchicine with IC50 = 4.97 µM/mL. Caspase-3, BAX, and Bcl-2 assays for 3a using annexin V-FITC staining revealed significant pro-apoptotic activity. Furthermore, multidrug-resistant leukemia SR cells were used to show better resistance indices (1.285 ng/mL, 1.15-fold) than the reference. Docking studies with β-tubulin indicate that most of the tested compounds illustrated good binding at the colchicine binding site of the enzyme, especially for compound 3a, which made several interactions better than that of the reference colchicine.

Thiazole-containing compounds as therapeutic targets for cancer therapy

In the last few decades, considerable progress has been made in anticancer agents development, and several new anticancer agents of natural and synthetic origin have been produced. Among heterocyclic compounds, thiazole, a 5-membered unique heterocyclic motif containing sulphur and nitrogen atoms, serves as an essential core scaffold in several medicinally important compounds. Thiazole nucleus is a fundamental part of some clinically applied anticancer drugs, such as dasatinib, dabrafenib, ixabepilone, patellamide A, and epothilone. Recently, thiazole-containing compounds have been successfully developed as possible inhibitors of several biological targets, including enzyme-linked receptor(s) located on the cell membrane, (i.e., polymerase inhibitors) and the cell cycle (i.e., microtubular inhibitors). Moreover, these compounds have been proven to exhibit high effectiveness, potent anticancer activity, and less toxicity. This review presents current research on thiazoles and elucidates their biological importance in anticancer drug discovery. The findings may aid researchers in the rational design of more potent and bio-target specific anticancer drug molecules.

2-(3,5-Dimethyl-1H-pyrazol-1-yl)thiazolo[4,5-b]pyridine

The compound 2-(3,5-dimethyl-1H-pyrazol-1-yl)thiazolo[4,5-b]pyridine (1) was synthesized with a yield of 71% by the reaction of 1-(thiazolo[4,5-b]pyridine-2-yl)hydrazine and acetylacetone. The structure was characterized by a single-crystal X-ray structure determination as well as 1H and 13C{1H} NMR spectroscopy. X-ray crystallography on 1 confirms the molecule consists of a pyridine–thiazole moiety and the pyrazole ring, and all non-hydrogen atoms are planar.

Design, Synthesis, and Cytotoxic Activity of 3-Aryl-N-hydroxy-2-(sulfonamido)propanamides in HepG2, HT-1080, KB, and MCF-7 Cells

A new series of (sulfonamido)propanamides (6a1-6a13, 6b1-6b15, 7c1-7c5, 6d1-6d5, 6e1-6e6) was designed and synthesized. All the synthesized compounds were characterized by NMR and mass spectrometry. The target compounds were evaluated for their in vitro cytotoxic activity against hepatocellular carcinoma (HepG2), fibrosarcoma (HT-1080), mouth epidermal carcinoma (KB), and breast adenocarcinoma (MCF-7) cell lines with the sulforhodamine B (SRB) assay, with gemcitabine and mitomycin C as positive controls. Most of these compounds exhibit a more potent cytotoxic effect than the positive control group on various cancer cell lines and the most potent compound, 6a7, shows the IC₅₀ values of 29.78±0.516 μm, 30.70±0.61 μm, and 64.89±3.09 μm in HepG2, HT-1080, KB, and MCF-7 cell lines, respectively. Thus, these compounds with potent cytotoxic activity have potential for development as new chemotherapy agents.