A series of eleven 1-methyl, 5-phenyl substituted thiosemicarbazones (MT1–MT11) were synthesized and tested for inhibitory activities against monoamine oxidases (MAOs) and acetylcholinesterase (AChE). MT5 inhibited MAO-B potently with IC50 = 8.77 μM and competitively inhibited MAO-B (Ki = 6.58 ± 0.064 μM) reversibly. Most compounds weakly inhibited AChE (<30% at 10 μM). MT5 and MT3 were non-toxic to VERO cells (IC50 = 191.96 and 187.04 μg/mL). Molecular docking and dynamics revealed MT5 stabilization via hydrogen bonding with Cys172 and π–π hydrophobic interaction with Tyr326. These results indicate that MT5 is a moderately selective, reversible, competitive MAO-B inhibitor with low cytotoxicity. © 2020 Elsevier B.V., All rights reserved.