A one‐pot multicomponent Biginelli reaction for the preparation of novel pyrimidinthione derivatives as antimicrobial agents

Synergistic effects of covalently coupled eosin-Y with Ben-graphitic carbon nitride framework for improved photocatalytic activity in solar light-driven Biginelli product generation and NADH regeneration

Elevated global pollution level is the prime reason that contributes to the onset of various harmful health diseases. The products of Biginelli reaction are enormously used in the pharmaceutical industry as they have antiviral, antibacterial, and calcium channel modulation abilities. This work reports a novel eosin Y sensitized boron graphitic carbon nitride (EY-Ben-g-C3N4) as a photocatalyst that efficiently produced 3,4-dihydropyrimidine-2-(1H)-one by the Biginelli reaction of benzaldehyde, urea, and methyl acetoacetate. The photocatalyst EY-Ben-g-C3N4 showed a successful generation of 3,4-dihydropyrimidine-2-(1H)-one (Biginelli product) in good yield via photocatalysis which is an eco-friendly method and has facile operational process. In addition to the production of Biginelli products, the photocatalyst also showed a remarkable NADH regeneration of 81.18%. The incorporation of g-C3N4 with boron helps increase the surface area and the incorporation of eosin Y which is an inexpensive and non-toxic dye, and in Ben-g-C3N4, enhanced the light-harvesting capacity of the photocatalyst. The production of 3,4-dihydropyrimidine-2-(1H)-one and NADH by the EY-Ben-g-C3N4 photocatalyst is attributed to the requisite band gap, high molar absorbance, low rate of charge recombination, and increased capacity of the photocatalyst to harvest solar light energy.

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.

Synthesis of 3,4-Dihydropyrimidin(thio)one Containing Scaffold: Biginelli-like Reactions

The interest in 3,4-dihydropyrimidine-2(1H)-(thio)ones is increasing every day, mainly due to their paramount biological relevance. The Biginelli reaction is the classical approach to reaching these scaffolds, although the product diversity suffers from some limitations. In order to overcome these restrictions, two main approaches have been devised. The first one involves the modification of the conventional components of the Biginelli reaction and the second one refers to the postmodification of the Biginelli products. Both strategies have been extensively revised in this manuscript. Regarding the first one, initially, the modification of one of the components was covered. Although examples of modifications of the three of them were described, by far the modification of the keto ester counterpart was the most popular approach, and a wide variety of different enolizable carbonylic compounds were used; moreover, changes in two or the three components were also described, broadening the substitution of the final dihydropyrimidines. Together with these modifications, the use of Biginelli adducts as a starting point for further modification was also a very useful strategy to decorate the final heterocyclic structure.

Antibacterial pyrazoles: tackling resistant bacteria

Bacterial resistance to antibiotics threatens our progress in healthcare, modern medicine, food production and ultimately life expectancy. Antibiotic resistance is a global concern, which spreads rapidly across borders and continents due to rapid travel of people, animals and goods. Derivatives of metabolically stable pyrazole nucleus are known for their wide range of pharmacological properties, including antibacterial activities. This review highlights recent reports of pyrazole derivatives targeting different bacterial strains focusing on the drug-resistant variants. Pyrazole derivatives target different metabolic pathways of both Gram-positive and Gram-negative bacteria.

Biginelli Reaction Mediated Synthesis of Antimicrobial Pyrimidine Derivatives and Their Therapeutic Properties

Antimicrobial resistance was one of the top priorities for global public health before the start of the 2019 coronavirus pandemic (COVID-19). Moreover, in this changing medical landscape due to COVID-19, finding new organic structures with antimicrobial and antiviral properties is a priority in current research. The Biginelli synthesis that mediates the production of pyrimidine compounds has been intensively studied in recent decades, especially due to the therapeutic properties of the resulting compounds, such as calcium channel blockers, anticancer, antiviral, antimicrobial, anti-inflammatory or antioxidant compounds. In this review we aim to review the Biginelli syntheses reported recently in the literature that mediates the synthesis of antimicrobial compounds, the spectrum of their medicinal properties, and the structure-activity relationship in the studied compounds.

In silico molecular docking studies of oxadiazole and pyrimidine bearing heterocyclic compounds as potential antimicrobial agents

Microbial resistance is a major problem faced by the scientific community. It has created an urgent need to develop antimicrobial agents with novel structures and mechanisms of action. With this aim, a series of novel 1,3,4-oxadiazoles bearing 3,4-dihydropyrimidine heterocyclic motifs 4a-l were designed and synthesized. One-pot Biginelli synthesis is pivotal due to the use of readily available chemicals, shorter reaction time, and ecofriendly synthesis with a good yield. The structures of the synthesized molecules were characterized and confirmed by infrared, ¹ H nuclear magnetic resonance (NMR), ¹³ C NMR, and mass spectroscopic techniques. The title compounds were screened against Gram-positive and -negative strains of bacteria and fungi using the Mueller-Hinton broth method. Compound 4d was found to be the most promising against Escherichia coli (12.5 µg/ml), whereas the same compound showed good activity against Staphylococcus aureus at a concentration of 50 µg/ml. Other compounds of the same series, 4c and 4h, displayed moderate activity against Streptococcus pyogenes at a concentration of 50 µg/ml. Furthermore, results of the antifungal activity tests revealed that compound 4i showed promising activity against all the strains of fungi, Candida albicans, Aspergillus niger, and Aspergillus clavatus, at concentrations of 100, 50, and 100 µg/ml, respectively. Molecular docking also showed that these compounds had a significant binding affinity (Glide docking score: -7.74 to -6.531) for DNA gyrase, engaging in a series of bonded and nonbonded interactions with residues lining the active site. The results of molecular docking study validated the experimental findings, thereby providing an initiation mark to optimize this motif using a structure-based drug design approach.

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.