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 ۴-{(۵-bromo-۲- hydroxybenzylidene)amino]methyl}cyclohexanecarboxylic acid (SB۱), ۴-{(۲-hydroxybenzylidene)amino]methyl}cyclohexanecarboxylic acid (SB۲), and ۴-{(۴-nitrobenzylidene)amino]methyl}cyclohexanecarboxylic acid (SB۳) in good yield. Their structures were confirmed based on spectroscopic data. The bases displayed considerable urease inhibitory activity with IC۵۰ (µg/mL) ۳۳.۴۱, ۴۰.۶۴, ۲۶.۱۸, and ۱۱.۱۴ for SB۱, SB۲, SB۳, and standard thiourea, respectively. They revealed weak antiradical activity in DPPH assay with EC۵۰ (µg/mL) ۱۱۳۸, ۱۲۳۹, and ۲۴۲۴۸ for SB۱, SB۲, and SB۳, respectively. In conclusion, grinding is an efficient and environmentally friendly method for synthesizing these bases, which may provide potential candidates for new medicines.