The primary objective of the proposed research is to develop new inhibitors of histone deacetylase (HDAC) with discrete selectivity for the human GI tract and proximal organs such as prostate, pancreas, liver and kidney. This goal is promoted by two key findings. First, colorectal cancer is the second leading cause of death from cancer in males and the third in females in the U.S. Secondly, it has been shown that glucoraphanin (GPN), the primary chemopreventive agent in broccoli undergoes myrosinase-dependent metabolism to afford a weak HDAC inhibitor. Evidence strongly suggests the GPN-derived HDAC inhibitor to be a cysteine conjugate similar in structure to C shown below. It is highly likely that the HDAC inhibiting metabolite is responsible for the beneficial chemopreventive effects associated not only with broccoli consumption but also the ingestion of many other vegetables that provide glucosinolates capable of GI-localized metabolism as shown below. Our goal is to generate new substances that share glucoraphanin's novel mechanism of action but are more potent HDAC inhibitors and thus more useful chemopreventive agents. We will first prepare a number of derivatives of the cysteine-conjugate derived from GPN to verify the hypothesis that the cysteine-derived carboxylate is responsible for Zn2+ coordination (and hence, enzyme inactivation) within the HDAC active site. From a library of primary amines, we will then prepare ITC analogs (like B shown below) and cysteine-1 inked conjugates (of type C). ITC and cysteine conjugates for each member of the library will be tested for HDAC inhibition in cell free assays (Fluor de Lys) and human colon cancer cells (HCT116). Agents that display anti-HDAC activity will be candidates for further synthetic and biochemical study. Specifically, glucosinolate precursors (of form A shown below) to these active agents will be constructed. The ability of resulting glucosinolates to undergo myrosinase-triggered conversion to the corresponding ITC will be assessed by automated reverse phase HPLC and, if applicable, we will examine the HDAC inhibition profile of said myrosinase-activated agents in both cell free assays and in HCT 116 cells. [unreadable] [unreadable] [unreadable]