HDAC9 and malignant colon neoplasm: To assess the cytotoxicity of the target compound CHC, MTT assays were conducted to quantify the cell viability of three human hepatocellular carcinoma (HCC) cell lines (SMMC-7721, Bel7402, and Huh7), human colon cancer cells (HCT116), and drug-resistant HCC cells (Bel7402/5-FU) after treatment with CHC, FDA-approved HDAC inhibitor SAHA, and harmine at different concentrations.