The Design And Synthesis Of Cyclopeptide Histone Deacetylases Inhibitors

Unbalanceable epigenetic modulation related to the tumor closed. Acetylation anddeacetylation of histone is one of the most important epigenetic modulations, whichcontrolled by histone deacetylases (HDACs) and histone acetyltransferases (HATs) in ourbody. It has been proved that inhibiting the activity of HDACs can induce the tumor celldifferentiation, apoptosis and inhibit the proliferation. So it has a prospect to design andsynthesize the anti-tumor drug according to the structures of HDACs.Cyclopeptide HDAC inhibitors have a lot of advantages, such as high activity, specificity,low cytotoxicity. FK228 is the only one that enters the phaseâ…¡clinic trial. So we considerFK228 as the lead compound. We consider thiol as the metal binding area. In the surfacerecognition area, introducing H-D-Pro-OH can stabilize the structure of cyclopeptide, andH-L-Ile-OH and H-Aib-OH can increase the activity. Thus we design the new cyclopeptideHDAC inhibitors: cyclo(-Am7 (S2Py)-Aib- Ile-D-Pro-).In order to strengthen the interreaction with HDAC, we introduce non-proteins aminoacids into cyclopeptide HDAC inhibitor we designed. Boc-L-Ab7-OH was synthesized usingBoc-2-amino-diethyl malonate and acetyl-2-amino-diethyl malonate as starting materialrespectively, and then we use acetylase and subtilisin to separate the racemic isomers to get it.The yields are 22.6% and 15.4% respectively. The result shows that the method ofconsidering Boc-2-amino-diethyl malonate as starting material and using subtilisin to separatethe racemic isomers can save time and be sufficient. So Boc-L-Phe(2-Me)-OH andBoc-L-Phe(3-Me)-OH were synthesized using Boc-2-amino-diethyl malonate as startingmaterial. Then we use subtilisin to separate the racemic isomers to get them in the yields of42.5% and 42.7%, respectively. And they were also characterized by IR, ~1H-NMR, MS andoptical rotation.The conventional liquid phase method was adopts to synthesize the cyclo(-Am7(S2Py)-Aib-Ile-D-Pro-). We use Boc to protect the amino group and Bzl to protect thecarboxyl. Usually, the coupling regrant is DCC-HOBt. But when Boc-Aib-OH coupled withdipeptide, we use HBTU-HOBt. After getting linear tetrapeptide, the Bzl and Boc will bedeprotected in turn, and deprotected tetrapeptide will cyclized in the high diluted solutionwith HATU-DIEA as cyclized reagent. Finally the bromine in the side chain was modified asbisulfide by two steps. The yield is 3.92%. The enzyme inhibitory trial in vitro shows that the inhibitory activity of cyclo(-Am7(S2Py)-Aib-Ile-D-Pro-) to HDAC1 is higher than that ofTSA, and is similar with that of FK228. Moreover, the inhibitory activity of cyclo(-Am7(S2Py)-Aib-Ile-D-Pro-) to HDAC1, HDAC4 are higher than to HDAC6, which indicates thatcyclo(-Am7 (S2Py)-Aib-Ile-D-Pro-) has a satisfied specificity.