A Practical Green Visit to the Functionalized [1,2,4]Triazolo[5,1-b ]quinazolin-8(4H )one Scaffolds Using the Group-Assisted Purification (GAP) Chemistry and Their Pharmacological Testing

Discovery of a new Bcl-2 inhibitor through synthesis, anticancer activity, docking and MD simulations

A database of 300 compounds was virtually screened and docked against Bcl-2 protein; the stability of the best-formed complex was evaluated through Molecular dynamics, the top ten compounds with the best in-silico complexation affinities were synthesized, and their In-vitro cytotoxic activity was examined. Thiazolidinone (4e) and isoxazoline (4a-d) were evaluated in-silico. For further evaluation and examination, we designed and synthesized from naturally occurring (R)-carvone and characterized it via spectroscopic analysis, as well as tested for their anticancer activities towards human cancer cell lines such as HT-1080 (fibrosarcome cancer), MCF-7 and MDA-MB-231 (breast cancer) and A-549 (lung cancer) by using MTT method with Doxorubicin as standard drug. Among them, compound 4d showed the most promising anticancer activity against HT-1080, A-549, MCF-7, and MDA-MB-231 cell lines with IC50 values of 15.59 ± 3.21 µM; 18.32 ± 2.73 µM; 17.28 ± 0.33 µM and 19.27 ± 2.73 µM respectively.Communicated by Ramaswamy H. Sarma.

An efficient, catalyst-free and aqueous ethanol-mediated synthesis of 5-((2-aminothiazol-5-yl)(phenyl)methyl)-6-hydroxypyrimidine-2,4(1H,3H)-dione derivatives and their antioxidant activity

In this study, we effectively developed a catalyst-free multicomponent synthesis of 5-((2-aminothiazol-5-yl)(phenyl)methyl)-6-hydroxypyrimidine-2,4(1H,3H)-dione derivatives employing 2-aminothiazole, N',N'-dimethyl barbituric acid/barbituric acid and different aldehydes at 80 °C in an aqueous ethanol medium (1 : 1) using group-assisted purification (GAP) chemistry. The essential characteristics of this methodology include superior green credential parameters, metal-free multicomponent synthesis, faster reaction times, greater product yields, simple product purification without column chromatography and higher product yields. All of the synthesized compounds were analyzed against the HepG2 cell line. Compounds 4j and 4k shows good anti-proliferative effects on HepG2 cells. Furthermore, the ABTS and DPPH scavenging assays were used to determine the antioxidant activity of all compounds (4a-r). In both ABTS and DPPH radical scavenging assays, compounds 4e, 4i, 4j, 4o and 4r exhibit excellent potency compared to the standard ascorbic acid.

Diphenhydramine Hydrochloride-CuCl as a New Catalyst for the Synthesis of Tetrahydrocinnolin-5(1H)-ones

The current study deals with the synthesis and characterization of a novel catalyst made from diphenhydramine hydrochloride and CuCl ([HDPH]Cl-CuCl). The prepared catalyst was thoroughly characterized using various techniques, such as ¹H NMR, Fourier transform-infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis and derivative thermogravimetry. More importantly, the observed hydrogen bond between the components was proven experimentally. The activity of this catalyst was checked in the preparation of some new derivatives of tetrahydrocinnolin-5(1H)-ones via a multicomponent reaction between dimedone, aromatic aldehydes, and aryl/alkyl hydrazines in ethanol as a green solvent. Also, for the first time, this new homogeneous catalytic system was effectively used for the preparation of unsymmetric tetrahydrocinnolin-5(1H)-one derivatives as well as mono- and bis-tetrahydrocinnolin-5(1H)-ones from two different aryl aldehydes and dialdehydes, respectively. The effectiveness of this catalyst was further confirmed by the preparation of compounds containing both tetrahydrocinnolin-5(1H)-one and benzimidazole moieties from dialdehydes. The one-pot operation, mild conditions, rapid reaction, and high atom economy, along with the recyclability and reusability of the catalyst, are other notable features of this approach.

Synthesis of N-(4-chlorophenyl) substituted pyrano[2,3-c]pyrazoles enabling PKBβ/AKT2 inhibitory and in vitro anti-glioma activity

A series of N-(4-chlorophenyl) substituted pyrano[2,3-c]pyrazoles was synthesised and screened for their potential to inhibit kinases and exhibit anticancer activity against primary patient-derived glioblastoma 2D cells and 3D neurospheres. A collection of 10 compounds was evaluated against glioma cell lines, with compound 4j exhibiting promising glioma growth inhibitory properties. Compound 4j was screened against 139 purified kinases and exhibited low micromolar activity against kinase AKT2/PKBβ. AKT signalling is one of the main oncogenic pathways in glioma and is often targeted for novel therapeutics. Indeed, AKT2 levels correlated with glioma malignancy and poorer patient survival. Compound 4j inhibited the 3D neurosphere formation in primary patient-derived glioma stem cells and exhibited potent EC₅₀ against glioblastoma cell lines. Although exhibiting potency against glioma cells, 4j exhibited significantly less cytotoxicity against non-cancerous cells even at fourfold-fivefold the concentration. Herein we establish a novel biochemical kinase inhibitory function for N-(4-chlorophenyl) substituted pyrano[2,3-c]pyrazoles and further report their anti-glioma activity in vitro for the first time.KEY MESSAGEAnti-glioma pyrano[2,3-c]pyrazole 4j inhibited the 3D neurosphere formation in primary patient-derived glioma stem cells. 4j also displayed PKBβ/AKT2 inhibitory activity. 4j is nontoxic towards non-cancerous cells.

Synthesis, crystal structure and in silico studies of novel 2,4-dimethoxy-tetrahydropyrimido[4,5-b]quinolin-6(7H)-ones

Herein, acetic acid mediated multicomponent synthesis of novel 2,4-dimethoxy-tetrahydropyrimido[4,5-b]quinolin-6(7H)-one (2,4-dimethoxy-THPQs) was reported. Single-crystal XRD analysis of four newly developed crystals of 2,4-dimethoxy-THPQs and their DFT study were also reported. The structure of all molecules was optimized using DFT B3LYP/6-31G(d) level and compared with the corresponding single-crystal XRD data. As a result, the theoretical and experimental geometrical parameters (bond lengths and bond angles) were found to be in good agreement. Frontier molecular orbital (FMO) and molecule electrostatic potential (MEP) analyses were used to investigate the physicochemical properties and relative reactivity of 2,4-dimethoxy-THPQs. The formation of strong C–H⋯O and N–H⋯O interaction was investigated by Hirshfeld analysis. Furthermore, electronic charge density concentration in 2,4-dimethoxy-THPQs was analysed by the Mulliken atomic charges which helps to predict the ability of 2,4-dimethoxy-THPQs to bind in the receptor. The molecular docking of the crystal structure of 2,4-dimethoxy-THPQs in the main protease (M^pro) of SARS-CoV-2 suggested that all four 2,4-dimethoxy-THPQs efficiently docked in M^pro. Furthermore, 2,4-dimethoxy-THPQs with a 3-chloro substitution in the phenyl ring have the highest binding affinity because of the additional formation of halogen bonds and highest dipole moment.

Single-crystal XRD analysis of 2,4-dimethoxy THPQs and their relative reactivity with properties were investigated using DFT calculation. Molecular docking studies show they effectively docked with main protease of SARS-CoV-2.

Microwave-assisted multicomponent synthesis of antiproliferative 2,4-dimethoxy-tetrahydropyrimido[4,5-b]quinolin-6(7H)-ones†

In this study, we demonstrate a simple, highly efficient, rapid and convenient series of 2,4-dimethoxy-tetrahydropyrimido[4,5-b]quinolin-6(7H)-ones 4a–v. Microwave irradiation facilitates the one-pot multicomponent reaction of different aromatic aldehydes, 6-amino-2,4-dimethoxypyrimidine and dimedone using glacial acetic acid. Metal-free multicomponent synthesis, shorter reaction time, higher product yield, easy product purification without column chromatography and outstanding green credential parameters are the key features of this protocol. We analysed 4a–v against six human tumour cell lines for antiproliferative activity. 4h, 4o, 4q and 4v show good antiproliferative activity with a good in silico ADMET profile. Furthermore, 4h, 4o, 4q and 4v also show drug-likeness properties by obeying drug-like filters.

Herein, we demonstrate a simple, rapid and green synthesis of 2,4-dimethoxy-THPQs under microwave irradiation and their antiproliferative activity, in silico ADMET and drug-likeness studies were carried out.

Advances in the application of 1,2,4-triazole-containing hybrids as anti-tuberculosis agents

Tuberculosis is a deadly communicable disease caused by the bacillus Mycobacterium tuberculosis (MTB), and pulmonary tuberculosis accounts for over 80% of the total cases. The 1,2,4-triazole is a privileged structure in the discovery of new drugs, and its derivatives act on various targets in MTB. In particular, 1,2,4-triazole hybrids can not only exert dual or multiple antitubercular mechanisms of action but also have the potential to enhance efficacy and reduce side effects. The present work aims to summarize the current status of 1,2,4-triazole hybrids as potential antitubercular agents, covering articles published between 2010 and 2020, to aid the further rational design of novel potential drug candidates endowed with higher efficacy, better compliance and fewer side effects.

Regio- and Diastereoselective Vicinal Aminobromination of Electron Deficient Olefins via Phosphorus-Based GAP Protocol

Chemical synthesis based on Group-Assisted Purification chemistry (GAP) has been prolifically used as a powerful, greener and ecofriendly tool so far. Herein, we report hypervalent iodine (III) mediated regio- and diastereoselective aminobromination of electron-deficient olefins using group-assisted purification (GAP) method. By simply mixing the GAP auxiliary-anchored substrates with TsNH2-NBS as nitrogen/bromine sources and PhI(OAc)2 as a catalyst, a series of vicinal bromoamines with multifunctionalities were obtained in moderate to excellent yields (53-94%). The vicinal bromoamines were obtained without column chromatography and/or recrystallization simply by washing the crude mixtures with cosolvents and thus avoiding wastage of silica, solvents, time, and labor. The GAP auxiliary is recyclable and reusable.

Tetramethylguanidine-functionalized melamine as a multifunctional organocatalyst for the expeditious synthesis of 1,2,4-triazoloquinazolinones

Novel nano-ordered 1,1,3,3-tetramethylguanidine-functionalized melamine (Melamine@TMG) organocatalyst was prepared and adequately identified by various techniques including FTIR, EDX, XRD and SEM spectroscopic or microscopic methods as well as TGA and DTG analytical methods. The Melamine@TMG, as an effective multifunctional organocatalyst, was found to promote smoothly the three-component synthesis of 1,2,4-triazoloquinazolinone derivatives using cyclic dimedone, 3-amino-1,2,4-triazole and different benzaldehyde derivatives in EtOH at 40 °C. This practical method afforded the desired products in high to excellent yields (86-99%) and short reaction times (10-25 min). The main advantages of this new method are the use of heterogeneous multifunctional nanocatalyst, simple work-up procedure with no need for chromatographic purification, highly selective conversion of substrates and recyclability of the catalyst, which could be used in five consecutive runs with only a small decrease in its activity.

Synthesis and in vitro study of antiproliferative benzyloxy dihydropyrimidinones

In this study, we report on antiproliferative benzyloxy dihydropyrimidinones (DHPMs) produced by the Biginelli reaction of benzyloxy benzaldehyde, urea, and diverse 1,3-diones. The reaction was catalyzed by lanthanum triflate and completed within 1-1.5 h, with 74-97% yield. The antiproliferative assay was carried out for all synthesized dihydropyrimidinones against six human solid tumor cell lines. Six compounds showed good antiproliferative activity with GI₅₀ values below 5 μM. Among all the synthesized compounds, the most potent derivative showed good antiproliferative activity against all cell lines with GI₅₀ values in the range of 1.1-3.1 μM. These DHPMs comply with druglikeness. Furthermore, ADMET prediction and the effect of P-glycoprotein on the antiproliferative activity were also studied. Overall, our method allows eco-friendly access to benzyloxy DHPMs as potential anticancer drugs.

Synthesis of (-)-epigallocatechin-3-gallate derivative containing a triazole ring and combined with cisplatin/paclitaxel inhibits NSCLC cancer cells by decreasing phosphorylation of the EGFR

Non-small-cell lung cancer is one of the principal causes of cancer-related death around the world. Chemotherapy is commonly used to treat wild type of epidermal growth factor receptor non-small-cell lung cancer. (-)-Epigallocatechin-3-gallate is the most abundant and active catechin. However, (-)-epigallocatechin-3-gallate has limited clinical application due to its poor stability and absorption. Herein, we report that a glycosylated azide undergoes a click reaction with the terminal alkyne of (-)-epigallocatechin-3-gallate to yield a triazole-linked glucose-(-)-epigallocatechin-3-gallate derivative and have evaluated its in vitro anticancer activity against human non-small-cell lung cancer cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The product inhibits human non-small-cell lung cancer cell lines with wild type of epidermal growth factor receptor and in combination with cisplatin/paclitaxel results in more pronounced proliferation inhibition than when used alone. Stability investigations indicates that the conjugated glucose residue can improve the stability of the (-)-epigallocatechin-3-gallate scaffold. Our studies suggest that the combination of the glucose-(-)-epigallocatechin-3-gallate derivative and chemotherapeutic drugs may provide a novel strategy for the treatment of non-small-cell lung cancer.

Hypervalent Iodine (III) Catalyzed Regio- and Diastereoselective Aminochlorination of Tailored Electron Deficient Olefins via GAP Chemistry

Herein, we report a protocol for highly efficient hypervalent iodine (III) mediated, group-assisted purification (GAP) method for the regioselectivities and stereoselective aminochlorination of electron-deficient olefins. A series of vicinal chloramines with multifunctionalities were acquired in moderate to excellent yields (45-94%), by merely mixing the GAP auxiliary-anchored substrates with dichloramine T and tosylamide as chlorine/nitrogen sources and iodobenzene diacetate as a catalyst. The vicinal chloramines were obtained without any column chromatographic purification and recrystallization simply by washing the reaction mixture with a minimum amount of common inexpensive solvents and thus avoiding wastage of silica, solvents, time, and labor. The GAP auxiliary is recyclable and reusable. This strategy is easy to handle, cost-effective, greener, sustainable, environmentally benign, and mostly suitable for the syntheses of vicinal haloamines from various electron-deficient alkenes.

Structural basis of quinolone derivatives, inhibition of type I and II topoisomerases and inquiry into the relevance of bioactivity in odd or even branches with molecular docking study

The structural modification of quinolone derivatives has been a hot spot in recent years, especially the modification of the N-1 position, which is the part that this article focuses on. In this paper, series of synthesized quinoline quaternary ammonium salts with odd and even carbon number alkyl groups in N-1 position were used to explain the influence of the alkyl side chain on activity. With respect to all the recently synthesized twenty products, the biological activity results exhibited significant antitumor and antibacterial activity with obvious differences in the target alkyliodine substituted compounds and the antibacterial activities apparently had the prominent odd-carbon number predominance. Compound 8-((4-(benzyloxy)phenyl)amino)-7-(ethoxycarbonyl)-5-propyl-[1,3]dioxolo[4,5-g]quinolin-5-ium (4d) was found to be the most potent derivative with IC₅₀ values of 4 ± 0.88, 4 ± 0.42, 14±1.96, and 32±3.66 against A-549, Hela, SGC-7901, and L-02 cells, respectively, stronger than the positive control 5-FU and MTX. Furthermore, it had the most potent bacterial inhibitory activity of MIC value against E. coli (ATCC 29213) and Staphylococcus aureus (ATCC 8739) at 3.125 nmol mL⁻¹. With respect to molecular simulations, in order to illustrate the possible mechanism of the difference between the series of compounds in the even or odd carbon chain alkyliodine substitution, this paper simulated the conceivable mode and explained the main interactions. Finally, we could find that the position and proportion of hydrogen bonds and other interactions in each series were regarded as the main reasons for this difference in activity.

Synthesis of Diastereoenriched α-Aminomethyl Enaminones via a Brønsted Acid-Catalyzed Asymmetric aza-Baylis-Hillman Reaction of Chiral N-Phosphonyl Imines

An effective chiral GAP methodology for preparing α-aminomethyl enaminones through a (R)-CSA-catalyzed asymmetric aza-Baylis-Hillman reaction is reported. Excellent yields and high diastereoselectivity could be obtained under mild conditions and convenient GAP techniques. The confirmations of the absolute configuration of N-phosphonyl imine and chiral enaminone by X-ray diffraction provides an explicit explanation of the chirality mechanism for GAP chemistry.

Pyridine-2-carboxylic acid as an effectual catalyst for rapid multi-component synthesis of pyrazolo[3,4-b]quinolinones

Green synthesis of pyrazolo[3,4-b]quinolinones was designed using bioproduct pyridine-2-carboxylic acid (P2CA) as a green and efficient catalyst. The multi-component reaction of aldehydes, 1,3-cyclodiones and 5-amino-1-phenyl-pyrazoles regioselectively produced pyrazolo[3,4-b]quinolinones in excellent yield (84–98%). Recyclization of the catalyst was also investigated. The electronic effect of the various substituents in aromatic rings indicated that the reaction proceeded through the carbocation intermediate. This newly designed protocol very quickly constructed products conventionally under milder conditions.

Green synthesis of pyrazolo[3,4-b]quinolinones was designed using bioproduct pyridine-2-carboxylic acid (P2CA) as a green and efficient catalyst.

A novel substrate directed multicomponent reaction for the syntheses of tetrahydro-spiro[pyrazolo[4,3-f]quinoline]-8,5′-pyrimidines and tetrahydro-pyrazolo[4,3-f]pyrimido[4,5-b]quinolines via selective multiple C–C bond formation under metal-free conditions

Substrate selectivity in the novel multi-component reaction of 5-aminoindazole, barbituric acid derivatives and aldehyde is explored.

Impact of an aryl bulky group on a one-pot reaction of aldehyde with malononitrile and N-substituted 2-cyanoacetamide

In this study, we successfully explored the effect of steric hindrance on the one-pot reaction of different aryl aldehydes with malononitrile and N-substituted 2-cyanoacetamide in the presence of piperidinium acetate as the catalyst. It involved the Knoevenagel condensation of the aldehyde and malononitrile to produce arylidene malononitrile as an intermediate, which was further treated with N-substituted 2-cyanoacetamide to give 6-amino-2-pyridone-3,5-dicarbonitrile derivatives when the less steric bulky group was involved. High steric hindrance changed the earlier reaction route and gave N-substituted 2-cyanoacrylamides via a slower route.

Impact of aryl bulky group on the one-pot reaction of aldehyde with malononitrile and N-substituted 2-cyanoacetamide is examined in the presence of piperidinium acetate as reusable catalyst.