Antibiotic resistance is one of the most serious threats to human health, food security and development today. New resistance mechanisms are emerging and spreading everywhere, threatening our ability to treat common infectious diseases. In this work, new semi-synthetic agents were synthesized based on a derivative of the natural compound Camphor, thiosemicarbazide and 2-acetyl/2-benzoylpyridine. For this purpose, thiosemicarbazones were synthesized in two steps. At the first step the N4-norbornylthiosemicarbazide was dissolved in ethanol with 2-acetylpyridine/2-benzoylpyridine. Concentrated hydrochloric acid was added to the obtained solution. At the second step the obtained 2-acetylpyridine hydrochloride N4-norbornylthiosemicarbazone (HL1) and 2-benzoylpyridine hydrochloride N4-norbornylthiosemicarbazone (HL2) were dissolved in ethanol and neutralized with an aqueous solution of Na2CO3. Then extraction with chloroform was done. The resulting substances were studied using FT-IR and NMR 1H, 13C spectroscopy. The copper(II) coordination compounds were obtained by reaction between HL1 or HL2 and copper(II) nitrate trihydrate, copper(II) chloride dihydrate, and copper(II) dicloroacetate. The complexes [Cu(L1,2)X] (X = NO3- (I, VI), Cl- (II, V), CHCl2COO- (III, VI)) were studied by elemental analysis, FT-IR spectroscopy and molar conductivity. The antibacterial activity against Gram-positive microorganisms: Staphylococcus aureus and Bacillus cereus was studied for the obtained substances. The results showed that 2-benzoylpyridine N4-norbornylthiosemicarbazone (HL2) is inactive one, and its copper(II) coordination compounds are 8 times less active than complexes with HL1 against Staphylococcus aureus and 32 times less active against Bacillus cereus. They in many cases surpass the activity of Furacillinum and are practically on the same level as Tetracycline, that are used in medicine.
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Novel semi-synthetic antibacterial agents against Staphylococcus aureus and Bacillus cereus
Published: 01 November 2023 by MDPI in 9th International Electronic Conference on Medicinal Chemistry session New Small molecules as drug candidates
https://doi.org/10.3390/ECMC2023-15686 (registering DOI)
Keywords: Coordination compounds; antibacterial activity; thiosemicarbazone: copper(II) complexes