Selective histone deacetylase (HDAC) 4 and HDAC5 inhibitor (IC50 values are 4.22, 11.9, 55.7, 320, 852, 881, and 1278 nM for HDAC 5, 4, 6, 1, 11, 2, and 8, respectively). Demonstrates activity against chemoresistant cancer cell lines in an MTT assay for cytotoxicity using human ovarian cancer cell lines A2780 and cisplatin resistant A2780CisR (IC50 = 0.49 and 0.32 μM respectively). Purity 98%. MW (observed): 294.35