Two protected single amino acid chelates,N~α-Fmoc-N~ε,N~ε-di((2,2-dimethyl-1,3-dithian-5-yl)methyl)-L-lysine(7) and N~α-Fmoc-N~ε-(2,2-dimethyl-1,3-dithian-5-yl)methyl,N~ε-Boc-L-lysine(9),were synthesized by modifying the side chain of lysine with 1,3-dithiane through direct reductive N-alkylation protocol.These amino acids have potential uses in peptide chemistry.
The total synthesis of a hydrated aurone derivative, 2-benzyl-4-methoxy-2,6-dihydroxybenzofuran-3（2H）-one, has been achieved for the first time with 2.4% overall yield. Using phloroglucinol as the starting material, the key steps included Friedel-Crafts acylation, Williamson synthesis, hydrogenolysis, aldol condensation, enolization and Rubottom oxidation.
CGRP receptor（CLR） is a B class GPCR that functions only when combined with RAMPs. CLR/RAMP1 has been regarded as a promising target for migraine treatment, as its antagonists have been proved to be effective recently. In the present study we designed and synthesized small molecular antagonists against CLR/RAMP1, resulting in a novel type of structure with acceptable high potency. The molecules were designed via virtual screening. Afterwards, a series of modification were conducted on the hit compounds, resulting in compound 8 as the best scored compound in docking, which was further validated in vitro by cell-based functional assay.
Cationic lipids have been applied to siRNA delivery for tumor therapeutics. However, the excess positive charges of these nanoplexes may lead to high cytotoxicity and nonnegligible immunogenicity both in vitro and in vivo, which limited the applications of gene drugs. We constructed multi-component lipoplex to delivery 3＇,3＂-bis-peptide-siRNA conjugate （pp-siRNA） by the treatment of melanoma. Based on the previous studies that the gemini lipid （CLD） encapsulated pp-siRNA, a novel neutral cytosin-l-yl- lipid （DNCA） was considered to replace a certain ration of CLD by hydrogen bonds and ~t-n stacking for reducing the cytotoxicity. It similarly retained in both the loading efficiency and targeted mRNA inhibition when DNCA was accounted for 40% in the lipoplex, with lower toxicity. Moreover, CLD/DNCA/pp-siRNA nanoplex could be uptake in A375 cells and internalized mainly by macropinocytosis and caveolin-mediated endocytosis. Besides, 90% CLD/DNCA/pp-siRNA nanoplexes presented the highest efficient knockdown for the mutant B-RAF mRNA （-80%）. All the results demonstrated that the mixed cationic and neutral lipids could efficiently realize the delivery of pp-siRNA and had potential application for cancer therapy.
A series of acyclic analogs of natural product Syringolin A （SylA） were designed and synthesized during our synthetic efforts for SylA. These acyclic analogs were prepared through a seven-step linear strategy, with total yields varying from 20%-34% for one type of analogs and 12%-18% for the other. These compounds bear a common structure of peptidyl vinyl amide, which reacts irreversibly with the proteasomal active site ThrlO^γ through Michael-type 1,4-addition. Therefore, these acyclic analogs may function the same way as SylA, as potential 20S proteasome inhibitors.
A new series of sulfonamide flavone derivatives are designed as non-covalent inhibitors of proteasome assisted with computer-aided drug design （CADD）. The desired compounds were synthesized successfully and the biological evaluation was subsequently accomplished. The results showed negligible improvement from our lead compound （IC50 for β5 subunit was 14.0 μM）. Thus, these flavone derivatives might be improved as potential 20S proteasome inhibitors.
Computer aided fragment-based lead discovery has been successfully applied to the design of inhibitors of aspartyl protease enzyme β-secretase（BACE1）.A benzimidamide fragment,which binds to the two catalytic aspartic acid residues in the active site of the enzyme,was selected as the starting compound.A novel series of 3-phenethylbenzimidamide inhibitors were designed and synthesized.Although biological evaluation results showed that the compounds displayed poor inhibitory activity towards BACE1,3-phenethylbenzimidamide analogs might be modified as potential BACE1 inhibitors.
