Fibrostat (Compound 5n) is a selective HDAC6 inhibitor that exerts antifibrotic effects by inhibiting HDAC6 activity, with an IC 50 value of 63 nM. It also exhibits good selectivity over HDAC1 , HDAC3 , HDAC5 , HDAC8 , HDAC10 , and HDAC11. Fibrostat significantly downregulates fibrotic markers (fibronectin and collagen 1) in fibroblasts. Additionally, Fibrostat demonstrated no toxicity in rat-perfused heart and zebrafish larvae models. Fibrostat shows potential for research into fibrosis-related diseases.