Preparation of some novel thiazolidinones, imidazolinones, and azetidinone bearing pyridine and pyrimidine moieties with antimicrobial activity

Antioxidant and Antimicrobial Potential of 1,8-Naphthyridine Based Scaffolds: Design, Synthesis and in Silico Simulation Studies within Topoisomerase II

A series of spiro β-Lactams (4 a-c, 7 a-c) and thiazolidinones (5 a-c, 8 a-c) possessing 1,8-naphthyridine moiety were synthesized in this study. The structure of the newly synthesized compounds has been confirmed by IR, 1H-NMR, 13C NMR, mass spectra, and elemental analysis. The synthesized compounds were tested in vitro for their antibacterial and antifungal activity against various strains. The antimicrobial data showed that most of the compounds displayed good efficacy against both bacteria and fungi. The structure-activity relationship (SAR) studies suggested that the presence of electron-withdrawing chloro (3 b, 4 b, and 5 b) and nitro groups (7 b, 8 b) at the para position of the phenyl ring improved the antimicrobial activity of the compounds. The free radical scavenging assay showed that all the synthesized compounds exhibited significant antioxidant activity on DPPH. Compounds 8 b (IC50=17.68±0.76 μg/mL) and 4 c (IC50=18.53±0.52 μg/mL) showed the highest antioxidant activity compared to ascorbic acid (IC50=15.16±0.43 μg/mL). Molecular docking studies were also conducted to support the antimicrobial and SAR results.

Construction and Docking Studies of Novel Pyrimido[4,5-b]quinolines as Antimicrobial Agents

In order to develop novel antimicrobial agents, we prepared quinoline bearing pyrimidine analogues 2-7, 8 a-d and 9 a-d and their structures were elucidated by spectroscopic techniques. Furthermore, our second aim was to predict the interactions between the active compounds and enzymes (DNA gyrase and DHFR). In this work, fourteen pyrimido[4,5-b]quinoline derivatives were prepared and assessed for their antimicrobial potential by estimating zone of inhibition. All the screened candidates displayed antibacterial potential with zone of inhibition range of 9-24 mm compared with ampicillin (20-25 mm) as a reference drug. Moreover, the target derivatives 2 (ZI=16), 9 c (ZI=17 mm) and 9 d (ZI=16 mm) recorded higher antifungal activity against C. albicans to that exhibited by the antifungal drug amphotericin B (ZI=15 mm). Finally, the most potent pyrimidoquinoline compounds (2, 3, 8 c, 8 d, 9 c and 9 d) were docked inside DHFR and DNA gyrase active sites and they recorded excellent fitting within the active regions of DNA gyrase and DHFR. These outcomes revealed us that compounds (2, 3, 8 c, 8 d, 9 c and 9 d) could be lead compounds to discover novel antibacterial candidates.

Design and construction of novel pyridine-pyrimidine hybrids as selective COX-2 suppressors: anti-inflammatory potential, ulcerogenic profile, molecular modeling and ADME/Tox studies

NSAIDs represent a mainstay in pain and inflammation suppression, and their actions are mainly based on inhibiting COX-1 and COX-2 enzymes.Due to the adverse effects of these drugs, especially on the stomach and heart, scientists efforts have been directed to manufacture selective COX-2 without cardiovascular side effects and with minimal effects on the stomach. The cardiovascular side effects are thought to be related to the chemical composition rather than mechanism of action of these drugs.Novel pyridopyrimidines, 9a-j, were prepared and their chemical structures were confirmed by NMR, mass and IR Spectra, and elemental analysis. The effect of the 9a-j compounds on COX-1 and COX-2 was assessed and it was found that 2-hydrazino-5-(4-methoxyphenyl)-7-phenyl-3H-pyrido[2,3-d)pyrimidin-4-one (9d) was the most potent COX-2 inhibitor (IC50 = 0.54 uM) compared to celecoxib (IC50 = 1.11 uM) with selectivity indices of 6.56 and 5.12, respectively.The in vivo inhibition of paw edema of novel compounds 9a-j was measured using carrageenan-induced paw edema method, and that 2-hydrazino-5-(4-methoxyphenyl)-7-phenyl-3H-pyrido[2,3-d)pyrimidin-4-one (9d) showed the best inhibitory activity in comparison with the other compounds and celecoxib.The gastroprotective effect of the potent derivatives 9d, 9e, 9f, 9 g and 9h was investigated. 2-Hydrazino-5-(4-methoxyphenyl)-7-phenyl-3H-pyrido[2,3-d)pyrimidin-4-one (9d) and 7-(chlorophenyl)-hydrazino-5-(4-methoxyphenyl)-3H-pyrido[2,3-d)pyrimidin-4-one (9e) showed ulcer indices comparable to celecoxib (1 and 0.5 vs 0.5, respectively). Docking studies were carried out and they confirmed the mechanistic action of the designed compoundsCommunicated by Ramaswamy H. Sarma.

Preparation and characterization of doped hollow carbon spherical nanostructures with nickel and cobalt metals and their catalysis for the green synthesis of pyridopyrimidines

Fused heterocyclic systems containing the pyrimidine ring structure perform a significant role in numerous biological and pharmaceutical processes. Their properties include antibacterial, antifungal, anti-fever, anti-tumor, and antihistamine. As pyridopyrimidines are important in the essential fields of pharmaceutical chemistry, efficient methods for preparing these heterocycles are presented. In this study, a method for producing improved hollow carbon sphere nanostructures with cobalt and nickel (Co-Ni@HCSs) is presented. The nanocatalyst was prepared and identified by applying Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET), and elemental mapping techniques. The Co-Ni@HCSs nanocatalyst was proved to be highly efficient in synthesizing pyranopyrimidine derivatives. The sizeable active site, economic catalyst loading, easy workup, reusability, green reaction conditions, and excellent yields of all derivatives are some of the significant features of this process. Also, applying response surface methodology (RSM) and the Box-Behnken design (BBD) techniques allowed us to determine the influential factors of the laboratory variables and identify the optimum conditions for superior catalytic activity. Finally, synthesized organic compounds were identified by utilizing melting point, FT-IR, and hydrogen-1 nuclear magnetic resonance (¹H NMR) analyses.

Inhibitors of glucosamine-6-phosphate synthase as potential antimicrobials or antidiabetics - synthesis and properties

Glucosamine-6-phosphate synthase (GlcN-6-P synthase) is known as a promising target for antimicrobial agents and antidiabetics. Several compounds of natural or synthetic origin have been identified as inhibitors of this enzyme. This set comprises highly selective l-glutamine, amino sugar phosphate or transition state intermediate cis-enolamine analogues. Relatively low antimicrobial activity of these inhibitors, poorly penetrating microbial cell membranes, has been improved using the pro-drug approach. On the other hand, a number of heterocyclic and polycyclic compounds demonstrating antimicrobial activity have been presented as putative inhibitors of the enzyme, based on the results of molecular docking to GlcN-6-P synthase matrix. The most active compounds of this group could be considered promising leads for development of novel antimicrobial drugs or antidiabetics, provided their selective toxicity is confirmed.

Green Design, Synthesis, and Molecular Docking Study of Novel Quinoxaline Derivatives with Insecticidal Potential against Aphis craccivora

An efficient and environmentally friendly method was established for designing novel 3-amino-1,4-dihydroquinoxaline-2-carbonitrile (1) via the reaction of bromomalononitrile and benzene-1,2-diamine under microwave irradiation in an excellent yield (93%). This targeted amino derivative was utilized for the construction of a series of Schiff bases (8-13). A new series of thiazolidinone derivatives (15-20) were synthesized in high yields (89-96%) via treatment of thioglycolic acid with Schiff bases (8-13) under microwave irradiation in high yields (89-96%). Moreover, new pyrimidine derivatives (26-30 and 35-38) were prepared by treatment of compound 1 with arylidenes (21-25) and/or alkylidenemalononitriles (31-34) using piperidine as a basic catalyst under microwave conditions. Based on elemental analyses and spectral data, the structures of the new assembled compounds were determined. The newly synthesized quinoxaline derivatives were screened and studied as an insecticidal agent against Aphis craccivora. The obtained results indicate that compound 16 is the most toxicological agent against nymphs of cowpea aphids (Aphis craccivora) compared to the other synthesized pyrimidine and thiazolidinone derivatives. The molecular docking study of the new quinoxaline derivatives registered that compound 16 had the highest binding score (-10.54 kcal/mol) and the thiazolidinone moiety formed hydrogen bonds with Trp143.

Novel 1,2-thiazine-pyridine hybrid: Design, synthesis, antioxidant activity and molecular docking study

Background & objectives:

1,2-thiazine and pyridine heterocycles drew much attention due to their biological activities including antioxidant activity. Based upon fragment based drug design, novel pyrido[1,2]thiazines 9a-c, thiazolidinopyrido[1,2]thiazines 10a-c and azetidinopyrido[1,2]thiazines 11a-c were designed and prepared.

Methods:

These novel derivatives 9a-c, 10a-c and 11a-c were subjected to screening for their antioxidant activity via various assays as DPPH radical scavenging potential, reducing power assay and metal chelating potential.

Results:

All the assayed derivatives exhibited excellent antioxidant potential and the tested compounds 9a, 9b, 10a, 10b, 11a and 11b exhibited higher DPPH scavenging potential (EC50 = 32.7, 53, 36.1, 60, 40.6 and 67 µM, respectively) than ascorbic acid (EC50 = 86.58 µM). While targets 9a, 10a and 11a (RP50 = 52.19, 59.16 and 52.25 µM, respectively) exhibited better reducing power than the ascorbic acid (RP50 = 84.66 µM). Computational analysis had been utilized to prophesy the bioactivity and molecular properties of the target compounds.

Conclusion:

To predict the binding manner of the novel derivatives as antioxidants, in-silico docking study had been performed to all the newly prepared compounds inside superoxide dismutase (SOD) and catalase (CAT) active site. The most active antioxidant candidate 9a (EC50 = 32.7 µM, RP50 = 52.19 µM) displayed excellent binding with Lys134 amino acid residing at Cu-Zn loop of SOD with binding energy score = -7.54 Kcal/mol thereby increase SOD activity and decrease reactive oxygen species.

Antioxidant, antimicrobial, and molecular docking studies of novel chalcones and Schiff bases bearing 1, 4-naphthoquinone moiety

Background:

The 1,4-naphthoquinone ring has attracted prominent interest in the field of medicinal chemistry due to its potent pharmacological activity as antioxidant, antibacterial, antifungal, and anticancer.

Objective:

Herein, a series of new Schiff bases (4-6) and chalcones (8a-c & 9a-d) bearing 1,4-naphthoquinone moiety were synthesized in good yields and were subjected to in-vitro antimicrobial, antioxidant, and molecular docking testing.

Methods:

A facile protocol has been described in this study for the synthesis of new derivatives (4-7, 8a-c, and 9a-d) bearing 1,4-naphthoquinone moiety. The chemical structures of all the synthesized compounds were identified by 1H-NMR, 13C-NMR, MS, and elemental analyses. Moreover, these derivatives were assessed for their in-vitro antimicrobial activity against gram-positive, gram-negative bacteria, and fungal strains. Further studies were conducted to test their antioxidant activity using DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging assay. Molecular docking studies were realized to identify the most likely interactions of the novel compounds within the protein receptor.

Results:

The antimicrobial results showed that most of the compounds displayed good efficacy against both bacterial and fungal strains. The antioxidant study revealed that compounds 9d, 9a, 9b, 8c, and 6 exhibited the highest radical scavenging activity. Docking studies of the most active antimicrobial compounds within GLN- 6-P, recorded good scores with several binding interactions with the active sites.

Conclusion:

Based on the obtained results, it was found that compounds 8b, 9b, and 9c displayed the highest activity against both bacterial and fungal strains. The obtained findings from the DPPH radical scavenging method revealed that compounds 9d and 9a exhibited the strongest scavenging potential. The molecular docking studies proved that the most active antimicrobial compounds 8b, 9b and 9c displayed the highest energy binding scores within the glucosamine-6-phosphate synthase (GlcN-6-P) active site.

The Bioactivity of Thiazolidin-4-Ones: A Short Review of the Most Recent Studies

Thiazolidin-4-ones is an important heterocyclic ring system of a pharmacophore and a privileged scaffold in medicinal chemistry. This review is focused on the latest scientific reports regarding biological activities of thiazolidin-4-ones published in 2020 and 2021. The review covers recent information about antioxidant, anticancer, anti-inflammatory, analgesic, anticonvulsant, antidiabetic, antiparasitic, antimicrobial, antitubercular and antiviral properties of thiazolidin-4-ones. Additionally, the influence of different substituents in molecules on their biological activity was discussed in this paper. Thus, this study may help to optimize the structure of thiazolidin-4-one derivatives as more efficient drug agents. Presented information may be used as a practical hint for rational design of new small molecules with biological activity, especially among thiazolidin-4-ones.