Solvent-free mechanochemical green synthesis of Schiff bases of tranexamic acid and study of their urease inhibitory and antioxidant activities

Three Schiff bases of tranexamic acid were successfully synthesized by a mechanochemical green method, which is 4-{(5-bromo-2- hydroxybenzylidene)amino]methyl}cyclohexanecarboxylic acid (SB1), 4-{(2-hydroxybenzylidene)amino]methyl}cyclohexanecarboxylic acid (SB2), and 4-{(4-nitrobenzylidene)amino]methyl}cyclohexanecarboxylic acid (SB3) in good yield. Their structures were confirmed based on spectroscopic data. The bases displayed considerable urease inhibitory activity with IC50 (µg/mL) 33.41, 40.64, 26.18, and 11.14 for SB1, SB2, SB3, and standard thiourea, respectively. They revealed weak antiradical activity in DPPH assay with EC50 (µg/mL) 1138, 1239, and 24248 for SB1, SB2, and SB3, respectively. In conclusion, grinding is an efficient and environmentally friendly method for synthesizing these bases, which may provide potential candidates for new medicines.