N-Aryl-N′-(chroman-4-yl)ureas and thioureas display in vitro anticancer activity and selectivity on apoptosis-resistant glioblastoma cells: Screening, synthesis of simplified derivatives, and structure–activity relationship analysis

Design, Synthesis, Computational Studies, and Anti-Proliferative Evaluation of Novel Ethacrynic Acid Derivatives Containing Nitrogen Heterocycle, Urea, and Thiourea Moieties as Anticancer Agents

In the present work, the synthesis of new ethacrynic acid (EA) derivatives containing nitrogen heterocyclic, urea, or thiourea moieties via efficient and practical synthetic procedures was reported. The synthesised compounds were screened for their anti-proliferative activity against two different cancer cell lines, namely, HL60 (promyelocytic leukaemia) and HCT116 (human colon carcinoma). The results of the in vitro tests reveal that compounds 1-3, 10, 16(a-c), and 17 exhibit potent anti-proliferative activity against the HL60 cell line, with values of the percentage of cell viability ranging from 20 to 35% at 1 μM of the drug and IC50 values between 2.37 μM and 0.86 μM. Compounds 2 and 10 showed a very interesting anti-proliferative activity of 28 and 48% at 1 μM, respectively, against HCT116. Two PyTAP-based fluorescent EA analogues were also synthesised and tested, showing good anti-proliferative activity. A test on the drug-likeness properties in silico of all the synthetised compounds was performed in order to understand the mechanism of action of the most active compounds. A molecular docking study was conducted on two human proteins, namely, glutathione S-transferase P1-1 (pdb:2GSS) and caspase-3 (pdb:4AU8) as target enzymes. The docking results show that compounds 2 and 3 exhibit significant binding modes with these enzymes. This finding provides a potential strategy towards developing anticancer agents, and most of the synthesised and newly designed compounds show good drug-like properties.

hERG stereoselective modulation by mexiletine-derived ureas: Molecular docking study, synthesis, and biological evaluation

Long QT syndrome (LQTS) is a disorder of cardiac electrophysiology resulting in life-threatening arrhythmias; nowadays, only a few drugs are available for the management of LQTS. Focusing our attention on LQT2, one of the most common subtypes of LQTS caused by mutations in the human ether-à-go-go-related gene (hERG), in the present work, the stereoselectivity of the recently discovered mexiletine-derived urea 8 was investigated on the hERG potassium channel. According to preliminary in silico predictions, in vitro studies revealed a stereoselective behavior, with the meso form showing the greatest hERG opening activity. In addition, functional studies on guinea pig isolated left atria, aorta, and ileum demonstrated that 8 does not present any cardiac or intestinal liability in our ex vivo studies. Due to its overall profile, (R,S)-8 paves the way for the design and development of a new series of compounds potentially useful in the treatment of both congenital and drug-induced forms of LQTS.

Medicinal chemistry aspects and synthetic strategies of coumarin as aromatase inhibitors: an overview

Coumarin is a bicyclic oxygen bearing heterocyclic scaffold formed by fusion of benzene with the pyrone ring. Because of its unique physicochemical characteristics and the ease with which it may be transformed into a wide range of functionalized coumarins during synthesis, coumarin provides a privileged scaffold for medicinal chemists. As a result, many coumarin derivatives have been developed, synthesized, and evaluated to target a variety of therapeutic domains, thereby making it an attractive template for designing novel anti-breast cancer compounds. The main culprit in estrogen overproduction in the estrogen-dependent breast cancer (EDBC), is the enzyme aromatase (AR), and it is thought to be a significant target for the effective treatment of EDBC. Considering coumarins versatility, this review presents a detailed overview of diverse study of aromatase as a target for coumarins. An overview of structure-activity relationship analysis of coumarin core is also included so as to summarize the desired pharmacophoric features essential for design and development of aromatase inhibitors (AIs) using coumarin core. Identification of key synthesis techniques that could aid researchers in designing and developing novel analogues with significant anti-breast cancer properties along with their mechanism of action have also been covered in the current review.

Synthesis of novel thiourea-/urea-benzimidazole derivatives as anticancer agents

A new series of urea and thiourea derivatives containing benzimidazole group as potential anticancer agents have been designed and synthesized. The structures of the synthesized compounds were characterized and confirmed by spectroscopic techniques such as 1H NMR, 13C NMR, and mass spectrometry. In vitro anticancer assay against two breast cancer (BC) cell lines, MDA-MB-231ER(−)/PR(−) and MCF-7ER(+)/PR(+), revealed that the cytotoxicity of 1-(2-(1H-benzo[d]imidazol-2-ylamino)ethyl)-3-p-tolylthiourea (7b) and 4-(1H-benzo[d]imidazol-2-yl)-N-(3-chlorophenyl)piperazine-1-carboxamide (5d) were higher in MCF-7 with IC50 values of 25.8 and 48.3 µM, respectively, as compared with MDA-MB-231 cells. Furthermore, 7b and 5d were assessed for their apoptotic potential using 4′,6-diamidino-2-phenylindole, acridine orange/ethidium bromide staining, and Caspase-3/7. After incubation with MCF-7, the compounds 7b and 5d induced apoptosis through caspase-3/7 activation. In conclusion, the compounds 7b and 5d are potential candidates for inducing apoptosis in different genotypic BC cell lines.

Discovery of new anticancer thiourea-azetidine hybrids: design, synthesis, in vitro antiproliferative, SAR, in silico molecular docking against VEGFR-2, ADMET, toxicity, and DFT studies

With the aim to discover potent and novel antitumor agents, a series of thiourea compounds bearing 3-(4-methoxyphenyl)azetidine moiety were designed according to the essential pharmacophoric features of the reported VEGFR-2 inhibitors and synthesized. All the synthesized compounds were evaluated for their in vitro anticancer activity against various human cancer cell lines (lung (A549), prostate (PC3), breast (MCF-7), liver (HepG2), colon (HCT-116), ovarian (SKOV-3), skin (A431), brain (U251) and kidney (786-O)). 3-(4-Methoxy-3-(2-methoxypyridin-4-yl)phenyl)-N-(4-methoxyphenyl)azetidine-1-carbothioamide (3B) was found to be most potent member against PC3, U251, A431, and 786-O cancer cell lines with EC₅₀ values 0.25, 0.6, 0.03, and 0.03 µM, respectively and showed more potency than Doxorubicin in PC3, A431, and 786-O cell lines. Compounds 1B to 7B showed EC₅₀ values ranging from 0.03 to 12.55 µM in A431 cell line. Compound 3-(4-methoxy-3-(pyridin-4-yl)phenyl)-N-(4-methoxyphenyl)azetidine-1-carbothioamide (1B) was found to be highly efficient in A431 and 786-O cell line with EC₅₀ values of 0.77 and 0.73 µM respectively. All the compounds exhibited good to moderate cytotoxic activity. The pharmacophoric features and molecular docking studies confirmed the potentialities of compounds 1B, 2B, 3B and 5B to be VEGFR-2 inhibitors. Moreover, in silico ADMET prediction indicated that most of the synthesized compounds have drug-like properties, possess low adverse effects and toxicity. In addition, the DFT studies for the most active compounds (1B and 3B) were carried out. In the end, our studies revealed that the compounds 1B and 3B represent promising anticancer potentialities through their VEGFR-2 inhibition.

Synthesis and antiproliferative screening of novel doubly modified colchicines containing urea, thiourea and guanidine moieties

A new series of 10-demethoxy-10-methylaminocolchicines bearing urea, thiourea or aguanidine moieties at position C7 has been designed, synthesized and evaluated for in vitro anticancer activity against different cancer cell lines (A549, MCF-7, LoVo, LoVo/DX). The majority of the new derivatives were active in the nanomolar range and were characterized by lower IC₅₀ values than cisplatin or doxorubicin. Two ureas (4 and 8) and thioureas (19 and 25) were found to be good antiproliferative agents (low IC₅₀ values and high SI) and could prove to be promising candidates for further research in the field of anticancer drugs based on the colchicine skeleton.

Modulation of mitochondrial respiration rate and calcium-induced swelling by new cromakalim analogues

A cellular model of cardiomyocytes (H9c2 cell line) and mitochondria isolated from mouse liver were used to understand the drug action of BPDZ490 and BPDZ711, two benzopyran analogues of the reference potassium channel opener cromakalim, on mitochondrial respiratory parameters and swelling, by comparing their effects with those of the parent compound cromakalim. For these three compounds, the oxygen consumption rate (OCR) was determined by high-resolution respirometry (HRR) and their impact on adenosine triphosphate (ATP) production and calcium-induced mitochondrial swelling was investigated. Cromakalim did not modify neither the OCR of H9c2 cells and the ATP production nor the Ca-induced swelling. By contrast, the cromakalim analogue BPDZ490 (1) induced a strong increase of OCR, while the other benzopyran analogue BPDZ711 (2) caused a marked slowdown. For both compounds, 1 displayed a biphasic behavior while 2 still showed an inhibitory effect. Both compounds 1 and 2 were also found to decrease the ATP synthesis, with pronounced effect for 2, while cromakalim remained without effect. Overall, these results indicate that cromakalim, as parent molecule, does not induce per se any direct effect on mitochondrial respiratory function neither on whole cells nor on isolated mitochondria whereas both benzopyran analogues 1 and 2 display totally opposite behavior profiles, suggesting that compound 1, by increasing the maximal respiration capacity, might behave as a mild uncoupling agent and compound 2 is taken as an inhibitor of the mitochondrial electron-transfer chain.

Chemoselective Hydrosilylation of the α,β-Site Double Bond in α,β- and α,β,γ,δ-Unsaturated Ketones Catalyzed by Macrosteric Borane Promoted by Hexafluoro-2-propanol

The B(C₆F₅)₃-catalyzed chemoselective hydrosilylation of α,β- and α,β,γ,δ-unsaturated ketones into the corresponding non-symmetric ketones in mild reaction conditions is developed. Nearly 55 substrates including those bearing reducible functional groups such as alkynyl, alkenyl, cyano, and aromatic heterocycles are chemoselectively hydrosilylated in good to excellent yields. Isotope-labeling studies revealed that hexafluoro-2-propanol also served as a hydrogen source in the process.

Recent advances in the discovery of small molecules targeting glioblastoma

Glioblastoma (GBM) is one of the most common central nervous system cancers. It is characterized as a fast-growing tumor that arises from multiple cell types with neural stem-cell-like properties. Additionally, GBM tumors are highly invasive, which is attributed to the presence of glioblastoma stem cells that makes surgery ineffective in most cases. Currently, temozolomide is the unique chemotherapy option approved by the U.S. Food and Drug Administration for GBM treatment. This review analyzes the emergence and development of new synthetic small molecules discovered as promising anti-glioblastoma agents. A number of compounds were described herein and grouped according to the main chemical class used in the drug discovery process. Importantly, we focused only on synthetic compounds published in the last 10 years, thus excluding natural products. Furthermore, we included in this review only those most biologically active compounds with proven in vitro and/or in vivo efficacy.

A sustainable strategy for the synthesis of bis-2-iminothiazolidin-4-ones utilizing novel series of asymmetrically substituted bis-thioureas as viable precursors

A series of bis-thioureas was synthesized as viable precursors for the design of bis-2-iminothiazolidin-4-ones utilizing the ultrasonic irradiation as a sustainable energy source.

Discovery and Characterization of R/S-N-3-Cyanophenyl-N'-(6-tert-butoxycarbonylamino-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)urea, a New Histone Deacetylase Class III Inhibitor Exerting Antiproliferative Activity against Cancer Cell Lines

A new series of N-aryl-N'-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)ureas bearing an alkoxycarbonylamino group at the 6-position were synthesized and examined as putative anticancer agents targeting sirtuins in glioma cells. On the basis of computational docking combined to in vitro sirtuin 1/2 inhibition assays, we selected compound 18 [R/S-N-3-cyanophenyl-N'-(6-tert-butoxycarbonylamino-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)urea] which displays a potent antiproliferative activity on various glioma cell types, assessed by quantitative videomicroscopy, eventually triggering senescence. The impact on normal glial cells was lower with a selectivity index of >10. Furthermore, human U373 and Hs683 glioblastoma cell lines served to demonstrate the inhibitory activity of 18 against histone deacetylase (HDAC) class III sirtuins 1 and 2 (SIRT1/2) by quantifying acetylation levels of histone and non-histone proteins. The translational potential of 18 was validated by an NCI-60 cell line screen and validation of growth inhibition of drug resistant cancer cell models. Eventually, the anticancer potential of 18 was validated in 3D glioblastoma spheroids and in vivo by zebrafish xenografts. In summary, compound 18 is the first representative of a new class of SIRT inhibitors opening new perspectives in the medicinal chemistry of HDAC inhibitors.

Preparation of glycosyl thiourea derivatives from glycosyl azides using sulfamic acid and sodium iodide in one-pot

Novel one-pot reaction conditions have been developed for the preparation of glycosyl thiourea derivatives directly from glycosyl azides mediated by a combination of sulfamic acid and sodium iodide. The reaction conditions were clean, non-toxic and the products were isolated in good to excellent yield.

Antimicrobial/Antibiofilm Activity and Cytotoxic Studies of β-Thujaplicin Derivatives

Natural β-thujaplicin displays a remarkable array of biological activities for the prevention or treatment of various disorders while its tropolone scaffold inspired the synthesis of new analogs. The main goal of the current study was to evaluate the influence of 4-substituted piperazine moieties at position 7 of the β-thujaplicin scaffold, on the antimicrobial activity. In order to determine the biological activity of the β-thujaplicin derivatives, a microdilution method was used against a wide variety of bacteria and fungi. Pseudomonas aeruginosa PAO 1 was used for testing antiquorum and antibiofilm effects. Four human tumor cell lines (MCF-7, NCI-H460, HeLa, and HepG2) and a porcine liver derived cell line (PLP2) were used for testing antitumor and cytotoxic activity. The compounds present better antibacterial and antifungal activity in comparison with approved antimicrobials used as control agents. β-Thujaplicin showed strong antibacterial and antifungal activities against all tested species. Further studies of their antibacterial activity revealed that all compounds presented good antibiofilm and antiquorum effects. Fungi were more susceptible than bacteria to the tested compounds, with the exception of MK150, which possessed the best antibacterial effect. None of the tested compounds, at the GI50 values obtained for the tumor cell lines, have shown toxicity for non-tumor liver cells (PLP2). The prediction of physicochemical properties of the compounds was performed to further explain the structure-activity relationship. Finally, in order to explore a possible mechanism of action of the synthesized compounds, molecular docking studies were performed on CYP51 (14-a lanosterol demethylase), an important component of the fungal cell membrane.

Synthesis and pharmacological evaluation of dehydroabietic acid thiourea derivatives containing bisphosphonate moiety as an inducer of apoptosis

A series of DHAA thiourea derivatives containing bisphosphonate moiety were designed and synthesized as potent antitumor agents. Structures of target molecules were confirmed using HR-MS, (1)H NMR and (13)C NMR and they exhibited potent anti-tumor activities against the SK-OV-3, BEL-7404, A549, HCT-116 and NCI-H460 tumor cell lines in vitro. Especially, compound 6e (IC50 = 1.79 ± 0.43 μM) exhibited the best anticancer activity against SK-OV-3 cell line. Its role as an inducer of apoptosis was investigated in this cell line by Annexin-V/PI binding assay and by following its capability for ROS generation, depolarization of mitochondrial transmembrane potential, activation of caspases and expression of pro- and anti-apoptotic proteins. Elevated level of ROS generation, activation of caspase-3, caspase-8, caspase-9, and Fas, higher expression of Bax, lower expression of Bcl-2, and increased level of Bax/Bcl-2 ratio identified 6e as a promising inducer of apoptosis that follows both of the mitochondria dependent pathway and the death receptor-mediated pathway. In addition, the cell cycle analysis indicated that compound 6e caused cell cycle arrest at G1 phase, induced apoptosis and led to cell death by increasing the proportion of sub-G1 cells. Furthermore, molecular docking studies showed that 6e could bind to the ATP pocket sites.

New imidazo[1,2-b]pyrazoles as anticancer agents: synthesis, biological evaluation and structure activity relationship analysis

Synthesis and functionalization strategies of the imidazo[1,2-b]pyrazole core were developed giving a rapid access to three series of novel imidazo[1,2-b]pyrazole type derivatives: C-2/C-6/C-7 trisubstituted, C-2/C-3/C-6 tri(hetero)arylated and C-2/C-3/C-6/C-7 tetrasubstituted imidazo[1,2-b]pyrazoles. 39 of the synthetized products were evaluated for in vitro anticancer activity using the MTT colorimetric assay against 5 human and 1 murine cancer cell lines. Promising in vitro growth inhibitory activities were exhibited by some of the target compounds. Of the 39 evaluated products, 4 displayed an IC50 ≤ 10 μM in the 6 cell lines analyzed (compounds 4d, 4g, 9a, 11a). A structure activity relationship analysis is also reported in this paper.

Cyclic versus hemi-bastadins. pleiotropic anti-cancer effects: from apoptosis to anti-angiogenic and anti-migratory effects

Bastadins-6, -9 and -16 isolated from the marine sponge Ianthella basta displayed in vitro cytostatic and/or cytotoxic effects in six human and mouse cancer cell lines. The in vitro growth inhibitory effects of these bastadins were similar in cancer cell lines sensitive to pro-apoptotic stimuli versus cancer cell lines displaying various levels of resistance to pro-apoptotic stimuli. While about ten times less toxic than the natural cyclic bastadins, the synthetically derived 5,5'-dibromohemibastadin-1 (DBHB) displayed not only in vitro growth inhibitory activity in cancer cells but also anti-angiogenic properties. At a concentration of one tenth of its in vitro growth inhibitory concentration, DBHB displayed actual antimigratory effects in mouse B16F10 melanoma cells without any sign of cytotoxicity and/or growth inhibition. The serum concentration used in the cell culture media markedly influenced the DBHB-induced antimigratory effects in the B16F10 melanoma cell population. We are currently developing a specific inhalation formulation for DBHB enabling this compound to avoid plasmatic albumin binding through its direct delivery to the lungs to combat primary as well as secondary (metastases) tumors.

4-Bromo-2-(piperidin-1-yl)thiazol-5-yl-phenyl methanone (12b) inhibits Na+/K(+)-ATPase and Ras oncogene activity in cancer cells

The in vitro growth inhibitory activity of 26 thiazoles (including 4-halogeno-2,5-disubtituted-1,3-thiazoles) and 5 thienothiazoles was assessed on a panel of 6 human cancer cell lines, including glioma cell lines. (4-Chloro-2-(piperidin-1-yl)thiazol-5-yl)(phenyl)methanone (12a) and (4-bromo-2-(piperidin-1-yl)thiazol-5-yl)(phenyl)methanone (12b) displayed ~10 times greater in vitro growth inhibitory activity than perillyl alcohol (POH), which therapeutically benefits glioma patients through the inhibition of both alpha-1 Na(+)/K(+)-ATPase (NAK) and Ras oncogene activity. The in vitro cytostatic activities (as revealed by quantitative videomicroscopy) displayed by 12a and 12b were independent of the intrinsic resistance to pro-apoptotic stimuli associated with cancer cells. Compounds 12a and 12b displayed relatively similar inhibitory activities on purified guinea pig brain preparations that mainly express NAK alpha-2 and alpha-3 subunits, whereas only compound 12b was efficacious against purified guinea pig kidney preparations that mainly express the NAK alpha-1 subunit, which is also expressed in gliomas, melanomas and non-small-cell lung cancers NSCLCs.