UDC 547-327:547.821:54.057

The aim. The combination in one molecule of pharmacophore fragments of thieno[2,3-d]pyrimidine-4-carboxylic acids with the fragments of 2-or 4-aminopyrimidine by peptide coupling promoted acylation in order to develop the new drug-like molecules with antimicrobial activity. Materials and methods. The molecular docking studies were performed with the AutoDock Vina and AutoDock-Tools 1.5.6 programs; TrmD Pseudomonas aeruginosa PDB ID – 5ZHN was used as the protein target. Synthetic methods of peptide coupling were used. 1H and 13C NMR spectra were recorded with a Varian-400 spectrometer at 400 MHz and Bruker Avance DRX 500 device at 500 MHz and 125 MHz in DMSO-d6 as a solvent, using TMS as the internal standard. LC-MS analysis of the compounds was carried out with Agilent 1100 HPLC з with at-mospheric pressure chemical ionization (APCI). The studied derivates were tested in vitro for their antibacterial and anti-fungal activities using agar diffusion and serial dilutions resazurin-based microdilution assays (RBMA). Results and discussion. By the combination of the pharmacophore fragments of thieno[2,3-d]pyrimidine-4-carboxylic acids with the fragments of 2-of 4-aminopyrimidine, the combinatorial library of amides was constructed. For this library of compounds, the potential of antimicrobial activity was revealed using docking studies to the TrmD enzyme isolated from P. aeruginosa. The peptide coupling promoted by 1,1’-carbonyldiimidazole was found to be effective for the synthesis of pyridyl amides of thieno[2,3-d]pyrimidine-4-carboxylic acids, and it allowed to combine these phar-macophores in one molecule. The results of antimicrobial activity study revealed the broad spectrum of antimicrobial activity for N-(pyridin-4-yl)-5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidine-4-carboxamide (2g), while 5,6-di-methyl-N-(6-methylpyridin-2-yl)thieno[2,3-d]pyrimidine-4-carboxamide (2c) showed the best MIC value against the reference strain of Pseudomonas aeruginosa ATCC 10145. N-(6-Methylpyridin-2-yl)-5,6,7,8-tetrahydro[1]benzothien-o[2,3-d]pyrimidine-4-carboxamide (2h) was also found to be active against Pseudomonas aeruginosa. Conclusions. An effective method for the synthesis of pyridyl amides of thieno[2,3-d]pyrimidine-4-carboxylic acid has been developed. The amides molecular docking method showed their ability to inhibit TrmD enzyme isolated from P. aeruginosa; the further in vitro studies of the compounds showed the rationality of the further studies of the derivatives with 2-ami-no-6-methylpyridine in amide substituent because this fragment favoured the selectivity against Pseudomonas aeruginosa. © The Author(s) 2023.

Author keywords

amides; antimicrobials; coupling; docking study; thieno[2, 3-d]pyrimidine

Abstract

In the literature, the chemical composition of Rhododendron tomentosum is mainly represented by the study of isoprenoid compounds of essential oil. In contrast, the study of the content of flavonoids will contribute to the expansion of pharmacological action and the use of the medicinal plant for medical purposes. The paper deals with the technology of extracts from Rh. tomentosum shoots using ethanol of various concentrations and purified water as an extractant. Extracts from Rh. tomentosum were obtained by a modified method that combined the effects of ultrasound and temperature to maximize the extraction of biologically active substances from the raw material. Using the method of high-performance thin-layer chromatography in a system with solvents ethyl acetate/formic acid/water (15:1:1), the following substances have been separated and identified in all the extracts obtained: rutin, hyperoside, quercetin, and chlorogenic acid. The total polyphenol content (TPC) and total flavonoid content (TFC) were estimated using spectrophotometric methods involving the Folin-Ciocalteu (F-C) reagent and the complexation reaction with aluminum chloride, respectively. A correlation analysis was conducted between antioxidant activity and the polyphenolic substance content. Following the DPPH assay, regression analysis shows that phenolic compounds contribute to about 80% (r2 = 0.8028, p < 0.05) of radical scavenging properties in the extract of Rh. tomentosum. The extract of Rh. tomentosum obtained by ethanol 30% inhibits the growth of test cultures of microorganisms in 1:1 and 1:2 dilutions of the clinical strains #211 Staphylococcus aureus and #222 Enterococcus spp. and the reference strain Pseudomonas aeruginosa ATCC 10145. © 2024 by the authors.

Author keywords

aluminum chloride; antimicrobial activity; antioxidant activity; chlorogenic acid; DPPH assay; Folin-Ciocalteu reagent; HPTL; hyperoside; Ledum palustre; quercetin; Rhododendron tomentosum; rutin; UV–Vis