Synthesis And Analysis Of A New Class Of Histone Deacetylase Inhibitors With Anticancer Bioactivity

Histone possesses two functions of both acetylation and deacetylation: the former is caused by histone acetylase (HAT) often associated with activated transcription, whereas the latter is catalyzed by histone deacetylase (HDAC) related to transcriptional silencing. Inhibition of HDAC activity represents a novel approach for intervening in cell cycle regulation; thus HDAC inhibitors possess great therapeutic potential in treatment of cell proliferative diseases. Several classes of HDAC inhibitors such as sodium butyrate, trichostain and trapoxin were reported to induce differentiation of several cancer cell lines and suppress cell proliferation. In this M.Sc. thesis taking innovation of innovate novel HDAC inhibitors as the mainline, four series of structurally modified benzamide derivatives with a postulated general structure were designed according to the lead compound MS-275. Four new series of benzamides were prepared through variation of substituted aryls, aryl substitutions, chain connections and functional groups. Both synthesis and analysis of these target compounds were done and the structure-activity relationships (SAR) were stated for HDAC inhibition and alterations in cellular function. The main contents and some results are illustrated as following:Four series of benzamide derivatives were synthesized and analyzed. The intermediate 4-[N-(substituted aryl-methoxycarbonyl)aminomethyl]-benzoic acids were prepared from substituted aryl methanols under the temperature of 0~10℃ with 60-84.1% yields, then converted to the active anhydrides with ethyl chloroformate and triethylamine under 0~5℃, or to carboxyl imidiazole with 1,1'-carbonylimidiazlole under 0~10℃, and then reacted with o-phenlenediamine or 2-fluorophenylamine, under room temperature for about 10h without further separation, or cyclohexyl-1,2-diamine separated by silica gel column chromatography to give target compounds in yield of 18-59%. Structural analysis was done by mass spectrometry, nuclear magnetic resonance, ultraviolet and infrared spectroscopy. The forth series of benzamides were synthesized by a green chemical strategy. Structure-activity relationship on the functional group moiety in HDAC inhibitors showed that substitution of 2'-amino(fluoro)phenyl or 2'-aminocyclohexyl resulted in decreasing or losing inhibitory activity. Results indicate that the 2'-aminophenyl groupin enzyme inhibiting regions which might act as a hydrogen-bonding or electrostatic interaction, was indispensable for inhibitory activity. The electronic influence of the aryl substituent in the hydrophobic moiety seemed to play a small role for HDAC inhibitory activity. In addition, the ability of most compounds to induce histone acetylation in cells correlated largely with their enzyme inhibitory activities in vitro against HDAC1. N-(2-aminophenyl)-4-[N-(pyridin-3-acryl aminomethyl)- benzamide in series 4 showed good HDAC inhibitory activity and pretty potent antiproliferative activities in vitro against various human cancer cell for further development.