DESIGN AND SYNTHESIS OF NEW PEPTIDOMIMETICS AS POTENTIAL INHIBITORS OF HIV-1 PROTEASE

Being HIV-1 protease responsible for the post-translational processing of the viral polyproteins and the subsequent generation of the structural and functional proteins, it is an important target for the treatment of AIDS. HIV-1 protease is an aspartyl protease active as an homodimer. Every single chain is built of 99 amino acids and the active site is at the interface between the two monomeric units. The commercially available protease inhibitors target the active site but several mutations within or outside the active site led to the emergence of resistance to these compounds. This thesis deals with the design and synthesis of peptides and peptidomimetics as potential inhibitors of HIV-1 protease that can circumvent drug resistance and that can be alternatives to active site PR inhibitors. Two different approaches were applied to reach our target. The first one, described in chapter 2, deals with the folding of the protease monomer that proceeds following a hierarchical succession of events starting from the formation of local elementary structures (LES), which contain highly conserved amino acids. The interaction between two complementary LES represents the first step of the folding process. Since these LES are so important for the protein, the virus can not afford their mutation. We describe here the synthesis of small peptides with the same sequence as one of these critical regions (p-LES) and of peptidomimetics analogues to the p-LES that could bind to the complementary region preventing the correct folding. CD studies of interaction between synthesized peptides and native sequence of the protease are presented. The second approach, described in chapter 3, consists in the design and synthesis of compounds mimetics of the terminal -sheet of the HIV-1 protease. The dimeric form of HIV-1 protease is stabilized by the antiparallel -sheet formed between the C- and N-terminal regions of the protein. Constrained molecular tongs based on a naphtalene scaffold in which peptidomimetic strands are attached through a carboxylpropyl link disrupt the dimeric enzyme with loss of activity. We are now concerned in decreasing the peptidic character and increasing the hydrosolubility of the molecular tongs. For that purpose, we have conceived two different strategies: 1) the synthesis of new peptidomimetic strands with increased hydrophilicity and 2) the introduction of hydrophilic groups on the scaffold mainly via metal-catalyzed cross coupling reactions. We describe here the synthesis and the biological activity against wild-type and mutated HIV-1 protease of these new molecular tongs.