Design, Synthesis, and In Silico Molecular Docking Study of Some Novel Thiochromene Derivatives with Antimicrobial Potential

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.

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.