Abstract In discovery of HDAC inhibitors (HDACIs) with improved anticancer potency, structural modification was performed on the previous derived indole-3-butyric acidderivative. Among all the synthesised compounds, molecule I13 exhibited high HDAC inhibitory and antiproliferative potencies in the in vitro investigations. The IC50 values of I13 against HDAC1, HDAC3, and HDAC6 were 13.9, 12.1, and