compounds of submicromolar concentrations of a histone deacetylase inhibitor , useful as anti - fibrotic agents . the compounds strongly inhibit three main features of myofibroblastic differentiation of cultured hepatic stellate cells and of skin fibroblasts : synthesis of collagens type i and iii , the predominant collagens in fibrosis of liver and other organs ; cellular proliferation ; and expression of smooth muscle α - actin , a marker for activated myofibroblasts . preferred compounds include trichostatin a or a pharmaceutically acceptable salt thereof , and sodium butyrate .