TB5 and TB8 interacts with the catalytic site of hMAO-B and hMAO-A with a competitive mode of inhibition. TB5 shows the best inhibitory activity and higher selectivity toward hMAO-B, with K _i and SI values of 0.11±0.01μM and 13.18, respectively. hMAO-B inhibition by compound TB5 and hMAO-A inhibition by compound TB8 are completely reversed after 24 h of dialysis. Cytotoxicity studies show TB5 is nontoxic at 5 and 25 μM, resulting in cell viabilities of 95.75% and 84.59 %, respectively.

Compounds are dissolved in DMSO (5 mg/mL) and diluted with PBS/EtOH (70:30).Kinetic analyses are carried out for TB5 and TB8. A set of Lineweaver–Burk plots are constructed in the absence and presence of various concentrations of compounds TB5 and TC8. The set consists of five graphs, each constructed by measuring MAO-B and MAO-A catalytic rates at different substrate concentrations (0.1-1 μM). The first Lineweaver–Burk plot is constructed in the absence of inhibitor, while the remaining four graphs are constructed in the presence of different concentrations of TB5 and TB8.