Synthesis of arylidene hydrazinylpyrido[2,3-d]pyrimidin-4-ones as potent anti-microbial agents

Novel spiro[indoline-3,2'thiazolo[5,4-e]pyrimido[1,2-a] pyrimidine] derivatives as possible anti-dermatophytic and anti-candidiasis agent

A novel series of 5'-benzylidene-3'-phenylspiro[indoline-3,2'-thiazolidine]-2,4'(1H)-diones 6a-d and spiro[indoline-3,2'-thiazolo[5,4-e]pyrimido[1,2-a]pyrimidin]-2(1H)-one 9a-d derivatives have been synthesized. All the newly synthesized compounds were evaluated for antifungal and anti-candidiasis activity by using Disc Diffusion and Modified Microdilution methods. The antimicrobial experiments have shown that the synthesized compounds demonstrated broad-spectrum antifungal activity in vitro. Among them, compounds 9a-9d had stronger antifungal activity against Trichophyton rubrum, Trichophyton mentagrophytes, and Candida albicans; compounds 6a-d also showed significant antifungal activity against selected fungal strains as compared to ketoconazole, the reference antifungal drug. The evaluation of antifungal activity against drug-resistant fungal variants showed that the designed compounds had significant antifungal activity against the tested variants. The combination of compounds (6a-d) and (9a-d) exhibited that the synthesized compounds had synergistic effects or additive effects. These results demonstrated that the synthesized compounds were putative chitin synthase inhibitors exhibiting broad spectrum antifungal activities. The present results indicate that novel spiro pyrimidine derivatives can be used as an active pharmaceutical ingredient for novel drug candidate for treatment of dermatophytosis and other fungal agents.

Synthesis, anticancer activity and molecular docking of new quinolines, quinazolines and 1,2,4-triazoles with pyrido[2,3-d] pyrimidines

Recently, heterocyclic compounds such as pyrido [2,3-d] pyrimidinones, 1,2,4-triazolopyrimidines, pyrimidoquinazolines, and quinoline derivatives have gained attention from researchers due to their pharmacological and biological activities. To synthesize new compounds, quinoline-2-thioxopyrido [2,3-d] pyrimidinone (1) and methylthioquinoline-pyrido [2,3-d] pyrimidinones (2) were used as starting materials. The new compounds synthesized were quinoline-pyrido [2,3-d] (DeGoey et al., 2013; Gouda et al., 2020; Dangolani et al., 2018) [1, 2,4]triazolopyrimidinones (5a-d), 2-methylsulfonyl-quinoline-pyrido [2,3-d]pyrimidinone (6), pyrido [2,3-d]pyrimidine derivatives, pyridopyrimido (Gouda et al., 2020; DeGoey et al., 2013) 2,12,1-b] quinazoline (9), pyrido [(Khajouei et al., 2021; Gouda et al., 2020) 3,23,2-e]bis (1,2,4-triazole)pyrimidine (12a,b) and pyridopyrimido-diquinazoline-dione (16) derivatives. These compounds were synthesized with high efficiency, producing yields ranging from 69% to 90%, under moderate conditions, through treating (2) or (10) with various reagents such as anthranilic acid, phosphorus oxychloride, hydrazine hydrate, formic acid, glacial acetic acid, arylamine (aniline, 4-chloroaniline, or 4-methoxyaniline), and sec-amine (piperazine or morpholine). The new structures of the synthesized compounds were verified using various spectroscopic procedures, such as IR, NMR, and mass spectra. Molecular docking studies were carried out to investigate and discuss how the prepared compounds bind to amino acids such as Estrogen Receptor alpha, EGFR, and NADPH oxidase protein. Also, the synthesized products were tested for their anticancer and antioxidant activities against the (MCF-7) breast carcinoma cell line and human normal Retina pigmented epithelium cells (RPE-1). The study on the structure-activity relationship (SAR) established a correlation between the chemical structure of the newly synthesized compounds and their anticancer activity. The findings suggest that compounds 5a-d, 9,12a-b, and 16 exhibited promising anticancer activity and antioxidant effects as measured by DPPH inhibition.

Synthesis, Antifungal Ergosterol Inhibition, Antibiofilm Activities, and Molecular Docking on β-Tubulin and Sterol 14-Alpha Demethylase along with DFT-Based Quantum Mechanical Calculation of Pyrazole Containing Fused Pyridine-Pyrimidine Derivatives

Multidrug-resistant fungal infections have become much more common in recent years, especially in immune-compromised patients. Therefore, researchers and pharmaceutical professionals have focused on the development of novel antifungal agents that can tackle the problem of resistance. In continuation to this, a novel series of pyrazole-bearing pyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione derivatives (4a-4o) have been developed. These compounds have been screened against Candida albicans, Aspergillus niger, and Aspergillus clavatus. The synthesized compounds were characterized by well-known spectroscopic techniques, i.e., IR, 1H NMR, 13C NMR, and mass spectrometry. In vitro antifungal results revealed that compound 4n showed activity against C. albicans having MIC value of 200 μg/mL. To know the plausible mode of action, the active derivatives were screened for anti-biofilm and ergosterol biosynthesis inhibition activities. The compounds 4h, 4j, 4k, and 4n showed greater ergosterol biosynthesis inhibition than the control DMSO. To comprehend how molecules interact with the receptor, studies of molecular docking of 4k and 4n have been performed on the homology-modeled protein of β-tubulin. The molecular docking revealed that the active compounds 4h, 4j, 4k, 4l, and 4n interacting with the active site amino acid of sterol 14-alpha demethylase (PDB ID: 5v5z) indicate one of the possible modes of action of ergosterol inhibition activity. The synthesized compounds 4c, 4e, 4h, 4i, 4j, 4k, 4l, and 4n inhibited biofilm formation and possessed the potential for anti-biofilm activity. DFT-based quantum mechanical calculations were carried out to optimize, predict, and compare the vibration modes of the molecule 4a.

Novel Pyrimidine Derivatives as Antioxidant and Anticancer Agents: Design, Synthesis and Molecular Modeling Studies

The heterocyclic ring system of pyrido [2,3-d]pyrimidines is a privileged scaffold in medicinal chemistry, possessing several biological activities. The synthesis of the pyrimidine derivatives was performed via the condensation of a suitable α,β-unsaturated ketone with 4-amino-6-hydroxy-2-mercaptopyrimidine monohydrate in glacial acetic acid. Chalcones were synthesized, as starting materials, via the Claisen-Schmidt condensation of an appropriately substituted ketone and an appropriately substituted aldehyde in the presence of aqueous KOH 40% w/v in ethanol. All the synthesized compounds were characterized using IR, ¹H-NMR, ¹³C-NMR, LC-MS and elemental analysis. The synthesized compounds were evaluated for their antioxidant (DPPH assay), anti-lipid peroxidation (AAPH), anti-LOX activities and ability to interact with glutathione. The compounds do not interact significantly with DPPH but strongly inhibit lipid peroxidation. Pyrimidine derivatives 2a (IC₅₀ = 42 μΜ), 2f (IC₅₀ = 47.5 μΜ) and chalcone 1g (IC₅₀ = 17 μM) were the most potent lipoxygenase inhibitors. All the tested compounds were found to interact with glutathione, apart from 1h. Cell viability and cytotoxicity assays were performed with the HaCaT and A549 cell lines, respectively. In the MTT assay towards the HaCaT cell line, none of the compounds presented viability at 100 μM. On the contrary, in the MTT assay towards the A549 cell line, the tested compounds showed strong cytotoxicity at 100 μM, with derivative 2d presenting the strongest cytotoxic effects at the concentration of 50 μΜ.

Preventive and curative effect of difenoconazole + azoxytrobin and thiophanate-methyl against lucky bamboo anthracnose disease caused by Colletotrichum dracaenophilum

In Egypt, Dracaena sanderiana (lucky bamboo) is an ornamental plant imported from several countries. Two weeks after they arrived at the nurseries, anthracnose indications were detected on the shoots of imported D. sanderiana samples. Four Colletotrichum spp. isolates were obtained from the symptomatic lucky bamboo plants. The obtained isolates belonged to the species of C. gloeosporioides or C. dracaenophilum based on their morphological characteristics and molecular biology analyses. Pathogenicity tests reveal that C. dracaenophilum isolate 4 was found to be more pathogenic than the other isolates. The in vitro investigation was conducted with the objectives of evaluating six systemic fungicides for their inhibitory effect against C. dracaenophilum. Data reveal that, thiophanate-methyl and difenoconazole + azoxytrobin at ≥15 ppm completely inhibited the pathogen growth. Tebuconazole and flusllazole inhibited growth completely at ≥20 ppm, whereas iprodione and cyprodinil + fludioxonil had a lower effect (56.6 and 54.4% reduction, respectively) at this dose. The in vivo investigation was conducted with the objectives of evaluating the preventive and curative effects of the most effective fungicides against anthracnose disease. Lucky bamboo plants were treated with fungicide and either inoculated or not with C. dracaenophilum before being left for 25 or 60 days. On both insidiously infected and vaccinated lucky bamboo plants, the combination of difenoconazole, azoxytrobin, and thiophanate-methyl at 20 ppm greatly reduced the development of anthracnose. Tebuconazole and flusllazole were found to be phytotoxic.

Synthesis and Molecular Docking Study of Novel Pyrimidine Derivatives against COVID-19

A novel series of pyrido[2,3-d]pyrimidines; pyrido[3,2-e][1,3,4]triazolo; and tetrazolo[1,5-c]pyrimidines were synthesized via different chemical transformations starting from pyrazolo[3,4-b]pyridin-6-yl)-N,N-dimethylcarbamimidic chloride 3b (prepared from the reaction of o-aminonitrile 1b and phosogen iminiumchloride). The structures of the newly synthesized compounds were elucidated based on spectroscopic data and elemental analyses. Designated compounds are subjected for molecular docking by using Auto Dock Vina software in order to evaluate the antiviral potency for the synthesized compounds against SARS-CoV-2 (2019-nCoV) main protease M ^pro. The antiviral activity against SARS-CoV-2 showed that tested compounds 7c, 7d, and 7e had the most promising antiviral activity with lower IC₅₀ values compared to Lopinavir, "the commonly used protease inhibitor". Both in silico and in vitro results are in agreement.

Synthesis and Antimicrobial, Anticancer and Anti-Oxidant Activities of Novel 2,3-Dihydropyrido[2,3-d]pyrimidine-4-one and Pyrrolo[2,1-b][1,3]benzothiazole Derivatives via Microwave-Assisted Synthesis

In our attempt towards the synthesis and development of effective antimicrobial, anticancer and antioxidant agents, a novel series of 2,3-dihydropyrido[2,3-d]pyrimidin-4-one 7a–e and pyrrolo[2,1-b][1,3]benzothiazoles 9a–e were synthesized. The synthesis of 2-(1,3-benzo thiazol-2-yl)-3-(aryl)prop-2-enenitrile (5a–e) as the key intermediate was accomplished by a microwave efficient method. Via a new variety oriented synthetic microwave pathway, these highly functionalized building blocks allowed access to numerous fused heteroaromatic such as 7-amino-6-(1,3-benzo thiazol-2-yl)-5-(aryl)-2-thioxo-2,3dihydropyrido [2,3-d]pyrimidin-4(1H)-one 7a–e and 1-amino-2-(aryl)pyrrolo[2,1-b][1,3]benzothiazole-3-carbonitrile derivatives 9a–e in order to study their antimicrobial and anticancer activity. The present investigation offers effective and rapid new procedures for the synthesis of the newly polycondensed heterocyclic ring systems. All the newly synthesized compounds were evaluated for antimicrobial, anticancer and antioxidant activity. Compounds 7a,d, and 9a,d showed higher antimicrobial activity than cefotaxime and fluconazole while the remaining compounds exhibited good to moderate activity against bacteria and fungi. An anticancer evaluation of the newly synthesized compounds against the three tumor cell lines (lung cell NCI-H460, liver cancer HepG2 and colon cancer HCT-116) exhibited that compounds 7a, d, and 9a,d have higher cytotoxicity against the three human cell lines compared to doxorubicin as a reference drug. These compounds also exhibited higher antioxidant activity and a great ability to protect DNA from damage induced by bleomycin.

Synthesis, characterization, computational, antioxidant and fluorescence properties of novel 1,3,5-trimesic hydrazones derivatives

New photophysical and antioxidant materials of trimesic trihydrazide derivatives were synthesized by one-pot stage of trimesic trihydrazide and different aromatic aldehydes. All compounds were characterized by spectroscopic techniques (NMR, MS, and IR) and elemental analysis. The absorption and emission spectral characteristics of hydrazone derivatives were investigated. The absorption maxima showed red shift relative to the starting compound. While the emission maxima showed clear dependent on the type of substituents. The electron donating and electron withdrawing showed red and blue shifts relative to the starting compound, respectively. The compounds’ effectiveness as antioxidant was estimated by DPPH radical scavenging and ABTS radical cation assays in vitro which indicated that the derivatives could be used as potential antioxidants. In addition, compounds 3g, and 3i showed strong antioxidant activities according to the DPPH assay and compounds 3c and 3m exhibited good antioxidant activities in ABTS assay. Antimicrobial activity of the derivatives was estimated using a micro-broth dilution method. Furthermore, molecular geometries of all prepared derivatives were fully optimized using density functional theory (DFT) calculations at the 6-31G(d)/B3LYP level of theory.

Synthesis, antibacterial, anti-oxidant and molecular docking studies of imidazoquinolines

Quinoline and imidazole derivatives have been playing a significant role in functional bioactivities and were potentially used as antibacterial, antifungal, anticancer, and anti-inflammatory drugs. Owing to the limitation of drug resistance, herein we synthesized thio-, chloro-, and hydroxyl-functionalized various imidazoquinolines by molecular hybridization approach. All the imidazoquinoline derivatives were examined for their antibacterial activity against selected bacterial pathogens by the agar well diffusion method. In addition, the anti-oxidant efficacy of imidazoquinolines was also tested using ferric reducing antioxidant power (FRAP). Among them, electron-withdrawing (-Cl) substituent containing imidazoquinoline 5f showed higher antibacterial and anti-oxidant activities than other imidazoquinolines and reached the effectiveness of the standard. In addition, compounds 4f, 5e, and 3f showed moderate antibacterial activity and other derivatives displayed weak activity against various pathogens. Molecular docking studies were also performed on selected imidazoquinoline derivatives (3f, 4f, and 5f), which showed high docking score and strong binding energy values. These results revealed that thio-imidazoquinoline could assist as a prototype for the designing of multidrug-resistant antibiotics against various microbial organisms.