Synthesis and Characterization of Some Novel Thiosemicarbazones of Substituted Benzaldehydes and <i>N-</i>(Hepta-<i>O</i>-Acetyl-β-d-Lactosyl)Thiosemicarbazide

<p>A set of reaction conditions, including ionic liquids as catalysts, water as solvent and microwave-assisted heating method, had been investigated for the synthesis of hepta-<i>O</i>-acetyl-β-d-lactosyl thiosemicarbazones. Based on optimized conditions, namely, [HO(CH<sub>2</sub>)<sub>2</sub>NH<sub>3</sub>][OAc] as catalyst, water as solvent and 300 W microwave power, a series of substituted benzaldehyde hepta-<i>O</i>-acetyl-β-d-lactosyl thiosemicarbazones was synthesized by reaction of hepta-<i>O</i>-acetyl-β-d-lactosyl thiosemicarbazide with the corresponding substituted benzaldehydes. The high yields of 90–97% were achieved. Almost all of the obtained thiosemicarbazones exhibited remarkable antibacterial activity against <i>Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Enterobacter, Escherichia coli, Pseudomonas aeruginosa</i> and <i>Klebsiella pneumonia</i> in comparison with sulphamethoxazole and trimethoprim as drug references and antifungal activity against <i>Aspergillus niger, Candida albicans</i> and <i>Saccharomyces cerevisiae</i> in comparison with clotrimazole as drug reference. MIC values of the compounds range from 39.1 to 2500 μg/mL for bacterial activity and from 0.25 to 25.6 μg/mL for fungal activity.</p>