Synthesis and characterization of pyrazoline substitutes derived from thiophene chalcones and evaluation of their antibacterial and antifungal activity

Abstract

This research involved the synthesis of two pyrazoline ring derivatives from the reaction of chalcones containing thiophene rings. In the first step, chalcones B1 and B2 were prepared from the reaction of 5-bromothiophene-2-carbaldehyde with (2-acetylthiophene, 2-acetyl-5-bromothiophene) in the presence of sodium hydroxide as a catalyst. In the second step, the chalcones were ring-closed with 2-hydrazinobenzothiazole, in the presence of ethanol as a solvent, to obtain the new pyrazoline compounds B4 and B3. The prepared compounds were characterized by ¹H NMR _،¹³C NMR spectroscopy and FT-IR. The initial inhibitory activity of the compounds was evaluated against four types of bacteria: Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Escherichia coli, and two types of fungi: Trichoderma and Aspergillus Niger at a concentration of 25 mg/ml. Compound B3 showed the best inhibition against all bacteria and Trichoderma fungi, while it did not show any activity against Aspergillus Niger. This makes the prepared compound B3 a promising future antibiotic.