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

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-O-acetyl-β-d-lactosyl thiosemicarbazones. Based on optimized conditions, namely, [HO(CH₂)₂NH₃][OAc] as catalyst, water as solvent and 300 W microwave power, a series of substituted benzaldehyde hepta-O-acetyl-β-d-lactosyl thiosemicarbazones was synthesized by reaction of hepta-O-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 Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Enterobacter, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumonia in comparison with sulphamethoxazole and trimethoprim as drug references and antifungal activity against Aspergillus niger, Candida albicans and Saccharomyces cerevisiae 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.