HDAC-IN-34 (compound 27) is a potent HDAC inhibitor, with IC 50 values of 0.022 and 0.45 μM for HDAC1 and HDAC6 , respectively. HDAC-IN-34 can bind to DNA and cause DNA damage. HDAC-IN-34 causes cells apoptosis through p53 signaling pathway. HDAC-IN-34 exhibits significant anti-proliferation effect against HCT-116 cells, with an IC 50 of 1.41 μM.