Indolylmethylene benzo[h]thiazolo[2,3-b]quinazolinones: Synthesis,characterization and evaluation of anticancer and antimicrobial activities

A series of novel 10-((1H-indol-3-yl)methylene)-7-aryl-7,10-dihydro-5H-benzo[h]thiazolo[2,3-b]quinazolin-9(6H)-ones (8a–t) have been synthesized in good yields by the reaction of benzo[h]quinazoline-2(1H)-thiones (4a–f) with 2-chloro-N-phenylacetamide (5) followed by Knoevenagel condensation with various indole-3-carbaldehydes (7a–d) under conventional method. All the synthesized compounds were characterized by spectral studies and screened for their in vitro anticancer and antimicrobial activities. Compound 8c has exhibited excellent activity against MCF-7 (breast cancer cell line) than the standard drug Doxorubicin. Compound 8d against both the cancer cell lines, 8q against MCF-7 and 8c, 8h against HepG2 have also shown good activity. Remaining compounds have shown moderate activity against both the cell lines. Antimicrobial activity revealed that, the compound 8q and 8t against Staphylococcus aureus and 8i, 8k, 8l, 8q & 8t against Klebsiella pneumoniae have shown equipotent activity on comparing with the standard drug Streptomycin. Remaining compounds have shown significant antibacterial and comparable antifungal activities against all the tested microorganisms.     

New amide linked dimeric 1,2,3-triazoles bearing aryloxy scaffolds as a potent antiproliferative agents and EGFR tyrosine kinase phosphorylation inhibitors

A search for potent antiproliferative agents has prompted to design and synthesize aryloxy bridged and amide linked dimeric 1,2,3-triazoles (7a–j) by using 1,3-dipolar cycloaddition reaction between 2-azido-N-phenylacetamides (4a–e) and bis(prop-2-yn-1-yloxy)benzenes (6a–b) via copper (I)-catalyzed click chemistry approach with good to excellent yields. All the newly synthesized compounds have been screened for their in vitro antiproliferative activities against two human cancer cell lines. The compounds 7d, 7e, 7h, 7i and 7j have revealed promising antiproliferative activity against human breast cancer cell line (MCF-7), whereas, the compounds 7a, 7b, 7c, 7i and 7j were observed as potent antiproliferative agents against human lung cancer cell line (A-549). The active compounds against MCF-7 have been also analysed for their mechanism of action by the enzymatic study, which shows that the compounds 7d, 7h and 7j were acts as active EGFR tyrosine kinase phosphorylation inhibitors. In support to this biological study, the molecular docking as well as in silico ADME properties of all the newly synthesized hybrids were predicted.     

Synthesis of novel hetero ring fused pyridine derivatives; Their anticancer activity,CoMFA and CoMSIA studies

A series of novel furo[2,3-b]pyridine-2-carboxamide 4a–h/pyrido[3′,2′:4,5]furo[3,2-d] pyrimidin-4(3H)-one derivatives 5a–p were prepared from pyridin 2(1H) one 1 via selective O-alkylation with α-bromoethylester followed by cyclization, then reaction with different aliphatic primary amines to obtain 4 and further reaction with triethyl orthoacetate/triethyl orthoformate. Also prepared novel furo[2,3-b]pyridine-2-carbohydrazide Schiff’s bases 7a–h and pyrido [3′,2′:4,5]furo[3,2-d]pyrimidin-4(3H)-one derivatives 8a–h starting from furo[2,3-b]pyridine carboxylate derivatives 3 by reaction with hydrazine hydrate to form 6 and reaction with diverse substituted aldehydes and cyclization. Products 4a–h, 5a–p, 7a–h and 8a–h were screened against four human cancer cell lines (HeLa, COLO205, Hep G2 and MCF 7) and one normal cell line (HEK 293). Compounds 4e, 4f, 4g, 5h, 7c, 7d, 7e and 7f showed significant anticancer activity against all the cell lines at micro molar concentration and found to be non-toxic to normal cell line. Studies for HeLa, COLO205 and MCF-7 using CoMFA and CoMSIA. Models from 3D-QSAR provided a strong basis for future rational design of more active and selective HeLa, COLO205 and MCF-7 cell line inhibitors.     

Synthesis and docking studies of novel antitumor benzimidazoles

In this work, the benzimidazole-pyrrole conjugates 6a–h and benzimidazole-tetracycles conjugates 12–14 were prepared. The cytotoxicity of the compounds 3, 4a–h, 6a–h, 8, 10 and 12–14 was tested against lung cancer cell line A549. Compound 6b exhibited higher activity than the bis-benzoxazole natural product (UK-1), the standard. The tested 4g,h, 6a–h, 10 and 12–14 exhibited remarkable cytotoxicity activity against breast cancer cell line MCF-7 with higher activity than tamoxifen. Furthermore, compound 4h was found to be also more potent than doxurubicin. The antitumor promotion activity of synthesized compounds 4g,h, 6a–h, 10 and 12–14 has been estimated by studying their possible inhibitory effects on EBV-EA activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). Among the studied compounds, the inhibitory activities of compounds 8, 13 and 14 demonstrated strong inhibitory effects on the Epstein–Barr virus early antigen (EBV-EA) activation without showing any cytotoxicity on the Raji cells and their effects being stronger than that of a representative control, oleanolic acid.Moreover, the molecular docking of the new compounds into plasminogen activator (uPA) receptor has been in correlation with the antitumor activity. All synthesized compounds 3, 4a–h, 6a–h, 8, 10 and 12–14 were docked into same groove of the binding site of the native co-crystalized (4-iodobenzo[b]thiophene-2-carboxamidine) ligand (PDB code:1c5x) for activity explaination. Compounds 4h, 6b and 13, giving the best docking results, were further studied to estimate their effect on the level of uPA using AssayMax human urokinase (uPA) ELISA kit. In case of A549 cell line, compound 6 exhibited similar activity to MMC, and for MCF-7 cell line, compound 4h exhibited similar activity to doxorubicin, in inhibiting the expression of uPA.     

Design,synthesis, and biological evaluation of novel 1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-3-carboxamide analogs in MCF-7 and MDA-MB-468 breast cancer cell lines

A series of novel 1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-3-carboxamide analogs were designed and synthesized for developing pyrazinoindolone scaffolds as anti-breast cancer agents. Compounds 1h and 1i, having a furan-2-yl-methylamide and benzylamide group, respectively, exhibited more potent cytotoxicity in MDA-MB-468 triple-negative breast cancer (TNBC) cells than compounds possessing aliphatic groups. Compounds 2a and 2b, as (R)-enantiomers of 1h and 1i, also had inhibitory activity against MDA-MB-468 cells. Moreover, analogs (3a–b and 3d–e) bearing a benzyl group at the N-2 position showed more potent activity than gefitinib, as a potent EFGR-TK inhibitor. Especially, compound 3a exhibited selective cytotoxic activity against MDA-MB-468 cells; it also had a synergistic effect in combination with gefitinib against MDA-MB-468 cells. In addition, we confirmed that compounds 3a and 3d inhibit phosphorylation of Akt in MDA-MB-468 cells using western blot analysis. Therefore, these 1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-3-carboxamide analogs may be helpful for investigating new anti-TNBC agents.     

Synthesis and mechanistic studies of novel spin-labeled combretastatin derivatives as potential antineoplastic agents

Two series (14a–d and 21a–h) of novel spin-labeled combretastatin derivatives were synthesized and evaluated for cytotoxicity against four tumor cell lines (K562, SGC-7901, Hela and HepG-2). Simultaneously, a representative compound 21a was selected to investigate the antitumor mechanisms of these synthetic compounds. The results indicated that some of the compounds showed significant cytotoxicity against four tumor cell lines in vitro and were more active than etoposide, a clinically available anticancer drug. Among the newly synthesized compounds, 21a, 21b and 21c displayed the greatest cytotoxicity against three tested tumor cell lines (HEPG-2, BGC-832 and Hela), with IC₅₀ values ranging from 0.15 to 1.05 μM, compared with values of 0.014–0.403 μM for 3-amino-deoxycombretastatin A-4 (3). In addition, the mechanistic analysis revealed that compound 21a effectively interfered with tubulin dynamics to prevent mitosis in cancer cells, leading to cell cycle arrest and, eventually, dose dependent apoptosis.     

Synthesis,antimicrobial, and mosquito larvicidal activity of 1-aryl-4-methyl-3,6-bis-(5-methylisoxazol-3-yl)-2-thioxo-2,3,6,10b-tetrahydro-1H-pyrimido[5,4-c]quinolin-5-ones

A series of 1-aryl-4-methyl-3,6-bis-(5-methylisoxazol-3-yl)-2-thioxo-2,3,6,10b-tetrahydro-1H-pyrimido[5,4-c]quinolin-5-ones (6a–h) have been synthesized by cyclization of ethyl-3-aryl-4-(2-chlorophenyl)-6-methyl-1-(5-methylisoxazol-3-yl)-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates 4a–h with 3-amino-5-methylisoxazole 5. Compounds 4a–h were obtained by Biginelli reaction, by condensation of aromatic aldehyde 1, ethyl acetoacetate 2, and isoxazolyl thioureas 3 in a one-pot reaction catalyzed by ceric ammonium nitrite (CAN). Compounds 6a–h were tested for their antibacterial and antifungal activities against various bacterial and fungal strains. The results showed that these compounds exhibited good antibacterial and antifungal activity compared with that of standard antibiotics. Mosquito larvicidal activity of the newly synthesized compounds 6a–h is also studied against fourth instar larvae Culex quinquefasciatus. Some of the compounds are proved to be lethal for mosquito larvae.     

Synthesis and biological evaluation of benzo[b]furo[3,4-e][1,4]diazepin-1-one derivatives as anti-cancer agents

A new series of novel Podophyllotoxin-like benzo[b]furo[3,4-e][1,4]diazepin-1-ones possessing structural elements of 4-aza-2,3-didehydropodophyllotoxins with central diazepine ring was designed and synthesized as anti-cancer agents. In initial assessment, the cytotoxic activity of the synthesized compounds was evaluated against three cancer cell lines including MCF-7, PC3 and B16-F10 employing the MTT assay. Some of compounds (12h, 13a, 13c and 14b) showed significant cytotoxic activity. So, we investigated the cytotoxicity of compounds 12h, 13a, 13c and 14b, along with podophyllotoxin as the reference drug in different cancer cell lines including A549, A2780, DU145, HeLa, and normal Huvec cell line. Among these four compounds, 13c showed promising antiproliferative activity against all cancer cells stronger than the other compounds and comparable to reference drug podophyllotoxin in some cancer cells. All these four compounds did not show significant cytotoxicity on normal Huvec cell line. The flow cytometry analysis of the MCF-7, PC3 and A2780 human cancer cell lines treated with 13c showed that 13c, induced apoptosis in the MCF-7, PC3 and A2780 human cancer cell lines, which is in good agreement to its cytotoxic activity as well. Compound 13c did not show significant influence on tubulin assembly and exert its cytotoxic effects via induction of apoptosis and has potent and selective cytotoxic effects in cancer cells.     

Novel 3,4-dihydro-4-oxoquinazoline-based acetohydrazides: Design,synthesis and evaluation of antitumor cytotoxicity and caspase activation activity

In search for novel small molecules with antitumor cytotoxicity via activating procaspase-3, we have designed and synthesized three series of novel (E)-N′-benzylidene-4-oxoquinazolin-3(4H)-yl)acetohydrazides (5a-j, 6a-h, and 7a-h). On the phenyl ring ò the benzylidene part, three different substituents, including 2-OH-4-OCH₃, 4-OCH₃, and 4-N(CH₃)₂, were introduced, respectively. Biological evaluation showed that the acetohydrazides in series 5a-j, in which the phenyl ring of the benzylidene part was substituted by 2-OH-4-OCH₃ substituent, exhibited potent cytotoxicity against three human cancer cell lines (SW620, colon; PC-3, prostate; NCI-H23, lung). Most of the compounds, in this series, especially compounds 5c, 5b and 5h, also significantly activated caspase-3 activity. Among these, compound 5c displayed 1.61-fold more potent than PAC-1 as caspase-3 activator. Cell cycle analysis showed that compounds 5b, 5c, and 5h significantly arrested the cell cycle in G1 phase. Further apoptotic studies also demonstrated compounds 5b, 5c, and 5h as strong apoptotic cell death inducers. The docking simulation studies showed that these compounds could activate procaspase via chelating Zn²⁺ ion bound to the allosteric site of the zymogen.     

Probing the high potency of pyrazolyl pyrimidinetriones and thioxopyrimidinediones as selective and efficient non-nucleotide inhibitors of recombinant human ectonucleotidases

With the aim to discover novel, efficient and selective inhibitors of human alkaline phosphatase and nucleotide pyrophosphatase enzymes, two new series of pyrazolyl pyrimidinetriones (PPTs) (6a–g) and thioxopyrimidinediones (PTPs) (6h–n) were synthesized in good chemical yields using Knoevenagel condensation reaction between pyrazole carbaldehydes (4a–g) and pharmacologically active N-alkylated pyrimidinetrione (5a) and thioxopyrimidinedione (5b). The inhibition potential of the synthesized hybrid compounds was evaluated against human alkaline phosphatase (h-TNAP and h-IAP) and ectonucleotidase (h-NPP1 and h-NPP3) enzymes. Most of the tested analogs were highly potent with a variable degree of inhibition depending on the functionalized hybrid structure. The detailed structure-activity relationship (SAR) of PPT and PTP derivatives suggested that the compound with unsubstituted phenyl ring from PPT series led to selective and potent inhibition (6a; IC₅₀ = 0.33 ± 0.02 µM) of h-TNAP, whereas compound 6c selectively inhibited h-IAP isozyme with IC₅₀ value of 0.86 ± 0.04 µM. Similarly, compounds 6b and 6h were identified as the lead scaffolds against h-NPP1 and h-NPP3, respectively. The probable binding modes for the most potent inhibitors were elucidated through molecular docking analysis. Structure-activity relationships, mechanism of action, cytotoxic effects and druglikeness properties are also discussed.     

Synthesis and anticancer evaluation of 3-aryl-6-phenylimidazo[2,1-b]thiazoles

A series of new 3,6-diphenylimidazo[2,1-b]thiazole derivatives (4a–l) are synthesized and evaluated for their anticancer activity. Some of the synthesized compounds have shown potent anti-proliferative activity against HeLa, MDA-MB-231, A549 and THP1 human cancer cell lines. Among the active compounds, 3-(3-trifluoromethylphenyl)-6-phenylimidazo[2,1-b]thiazole (4j) has caused significant cytotoxicity in HeLa cells, with IC₅₀ as low as 6.5 μM. Compound 4j has induced caspase-3 and caspase-8 activation, leading to an apoptotic cell death. FACS analysis has revealed that compound 4j arrests cells in G0/G1 phase. The presence of 3-(3-trifluoromethylphenyl)- or 3-(3-chlorophenyl)-substituent, in that order, on the 6-phenylimidazo[2,1-b]thiazole impacts more positively than other aryl-substituents, on the anti-proliferative properties of these compounds.     

Synthesis and biological evaluation of novel C6-amino substituted 4-azasteroidal purine nucleoside analogues

Novel C6-amino substituted purine nucleoside analogues (2–12) bearing a modified pyranose-like D ring of the 4-azasteroid moiety were efficiently synthesized through nucleophilic substitution at C6 position of the steroidal nucleoside precursors (1a, b) with versatile amines. All the synthesized new compounds were evaluated for their anticancer activity in vitro against Hela, PC-3 and MCF-7 cell lines. Among them, compounds 4b, 7b and 9b exhibited significant cytotoxicity with the IC₅₀ values of 2.99 μM (PC-3), 2.84 μM, (PC-3) and 2.69 μM (Hela), respectively.     

4β-[4′-(1-(Aryl)ureido)benzamide]podophyllotoxins as DNA topoisomerase I and IIα inhibitors and apoptosis inducing agents

A series of 4β-[4′-(1-(aryl)ureido)benzamide]podophyllotoxin congeners (11a–l) were synthesized and evaluated for their cytotoxic activity against six human cancer cell lines. Some of the compounds like 11a, 11h, 11k and 11l showed significant anti-proliferative activity in Colo-205 cells and were superior to etoposide. The flow-cytometric analysis studies indicated that these compounds show strong G1 cell cycle arrest, as well exhibited improved inhibitory activities on DNA topoisomerase I and IIα enzymes. These compounds induce apoptosis by up regulating caspase-3 protein as observed by ELISA and Western blotting analysis. In addition, a brief structure–activity relationship studies within the series along with docking results of representative compounds 11a, 11h, 11k, 11l were presented.     

Design and synthesis of new substituted spirooxindoles as potential inhibitors of the MDM2–p53 interaction

The designed compounds, 4a–p, were synthesized using a simple and smooth method with an asymmetric 1,3-dipolar reaction as the key step. The chemical structures for all synthesized compounds were elucidated and confirmed by spectral analysis. The molecular complexity and the absolute stereochemistry of 4b and 4e designed analogs were determined by X-ray crystallographic analysis. The anticancer activities of the synthesized compounds were tested against colon (HCT-116), prostate (PC-3), and hepatocellular (HepG-2) cancer cell lines. Molecular modeling revealed that the compound 4d binds through hydrophobic–hydrophobic interactions with the essential amino acids (LEU: 57, GLY: 58, ILE: 61, and HIS: 96) in the p53-binding cleft, as a standard p53-MDM2 inhibitor (6SJ). The mechanism underlying the anticancer activity of compound 4d was further evaluated, and the study showed that compound 4d inhibited colony formation, cell migration, arrested cancer cell growth at G2/M, and induced apoptosis through intrinsic and extrinsic pathways. Transactivation of p53 was confirmed by flow cytometry, where compound 4d increased the level of activated p53 and induced mRNA levels of cell cycle inhibitor, p21.     

Unusual transformation of substituted-3-formylchromones to pyrimidine analogues: Synthesis and antimicrobial activities of 5-(o-hydroxyaroyl)pyrimidines

Substituted-3-formylchromones (4a–e) on reaction with 1,3-bis-dimethylaminomethylene-thiourea (5) in refluxing toluene solution give novel substituted 5-(o-hydroxyaroyl)pyrimidines (6a–e) in high yields. A mechanistic rationalization of the formation of products (6a–e) is proffered. Antimicrobial activities of all the synthesized compounds (6a–e) were evaluated against various fungal and bacterial strains. Compound 6d display significant antifungal activity (MIC 15) against Geotrichum candidum in comparison fluconazole used as positive control. Some of the compounds also display good antibacterial activity. Cytotoxic profile of compound 6d against HeLa cells indicates that at concentration (20 μM) no significant cell death (～2%) was observed.     

Design and synthesis of anti-breast cancer agents from 4-piperazinylquinoline: A hybrid pharmacophore approach

A novel class of 4-piperazinylquinoline derivatives based on the isatin scaffold were designed by molecular hybridization approach and synthesized for biological evaluation. Subsequently, the compounds were examined for their cytotoxic effects on two human breast tumor cell lines, MDA-MB468 and MCF7, and two non-cancer breast epithelial cell lines, 184B5 and MCF10A. Although all compounds examined were quite effective on the breast cancer cell lines examined, the compound 4-bromo-1-[4-(7-chloro-quinolin-4-yl)-piperazin-1-ylmethyl]-1H-indole-2,3-dione (5b) and N¹-[4-(7-trifluoromethyl-quinolin-4-yl)]-piperazin-1-ylmethyl-4-chloro-1H-indole-2,3-dione-3-thiosemicarbazone (8a) emerged as the most active among this series. It appeared that both 5b and 8a caused apoptosis to MCF7 cancer cells, but not MCF10A non-cancer cells. Thus, 4-piperazinylquinoline linked isatin analog can serve as the prototype molecule for further development of a new class of anti-breast cancer agents.     

Synthesis and antitumor activity of novel 1-substituted phenyl 3-(2-oxo-1,3,4-oxadiazol-5-yl) β-carbolines and their Mannich bases

A series of novel 1-(substituted phenyl)-3-(2-oxo-1,3,4-oxadiazol-5-yl) β-carbolines (4a–e) and the corresponding Mannich bases 5–9(a–c) were synthesized and evaluated for their in vitro antitumor activity against seven human cancer cell lines. Compounds of 4a–e series showed a broad spectrum of antitumor activity, with GI₅₀ values lower than 15 μM for five cell lines. The derivative 4b, having the N,N-dimethylaminophenyl group at C-1, displayed the highest activity with GI₅₀ in the range of 0.67–3.20 μM. A high selectivity and potent activity were observed for some Mannich bases, particularly towards resistant ovarian (NCI-ADR/RES) cell lines (5a, 5b, 6a, 6c and 9b), and ovarian (OVCAR-03) cell lines (5b, 6a, 6c, 9a, 9b and 9c). In addition, the interaction of compound 4b with DNA was investigated by using UV and fluorescence spectroscopic analysis. These studies indicated that 4b interact with ctDNA by intercalation binding.     

Synthesis and biological screening of a combinatorial library of β-chlorovinyl chalcones as anticancer,anti-inflammatory and antimicrobial agents

A combinatorial library of β-chlorovinyl chalcones (4) were synthesized by Claisen–Schmidt condensation reaction. Catalytic reaction of substituted 3-chloro-3-phenyl-propenal (2) and 1-(2,4-dimethoxy-phenyl)-ethanone or 1-(4-methoxy-phenyl)-ethanone (3) in alkaline conditions furnished the target compound 5-chloro-1-(2,4-dimethoxy-phenyl)-5-phenyl-penta-2,4-dien-1-one (4). The synthesized compounds were screened for their biological activity viz. anticancer, anti-inflammatory and antimicrobial activities. Synthesized compounds 4g and 4h revealed promising anti-inflammatory activity (66–67% TNF-α and 95–97% IL-6 inhibitory activity at 10 μM). Cytotoxicity of the compounds checked using CCK-8 cell lines and found to be nontoxic to slightly toxic. Furthermore, the anticancer activity (30–40%) was shown by compounds 4d, 4e, 4h and 4b at 10 μM concentrations against ACHN followed by Calu 1, Panc1, HCT116 and H460 cell lines. Some of the compounds 4d, 4e, 4a, 4i and 4b revealed promising antimicrobial activity at MIC 50–100 μg/mL against selected pathogenic bacteria and fungi.     

Solvent free synthesis,anti-inflammatory and anticancer activity evaluation of tricyclic and tetracyclic benzimidazole derivatives

Heterocyclic benzimidazole derivatives 3a–h, 5a–c and 7a–d have been synthesized by condensation of succinic acid (1) homophthalic acid (4) and 2,3-pyrazinedicarboxlic acid (6) with various substituted diamines under microwave irradiation in good yields. Structures assigned to 3a–h, 5a–c and 7a–d are fully supported by spectral data. All these compounds were screened for anti-inflammatory and anticancer activities. At a dose of 50 mg/kg po compounds 3b (39.4%) and 3c (39.2%) exhibited anti-inflammatory activity, comparable to standard ibuprofen which showed 39% activity at 50 mg/kg po and compound 7c exhibit good anticancer activity against ovary (IGR-OV-1), breast (MCF-7) and CNS(SF-295) human cancer cell lines.     

Anti-cancer potential of (1,2-dihydronaphtho[2,1-b]furan-2-yl)methanone derivatives

A series of 1,2-dihydronaphtho[2,1-b]furan derivatives were synthesized by cyclizing 1-(aryl/alkyl(arylthio)methyl)-naphthalen-2-ol and pyridinium bromides in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in very good yield. The synthesized compounds were evaluated for their anti-proliferative potential against human triple negative MDA-MB-468 and MCF-7 breast cancer cells and non-cancerous WI-38 cells (lung fibroblast cell) using MTT experiments. Among 21 synthesized compounds, three compounds (3a, 3b and 3 s) showed promising anti-cancer potential and compound 3b was found to have best anti-proliferative activities based on the results of several biochemical and microscopic experiments.