Synthesis of potent and orally active HIV-protease inhibitors

Synthesis and Pharmacological Evaluation of CGP 57813 and CGP 61755, HIV-1 Protease Inhibitors from the Phe-c-Phe Peptidomimetic Class

In this report we describe the enzyme inhibitory, antiviral and pharmacokinetic properties of CGP 57813 and CGP 61755, structural analogues of CGP 53437 that were synthesized in an attempt to obtain human immunodeficiency virus type 1 (HIV-1) protease inhibitors with improved selectivity and oral bioavailability. CGP 57813 inhibited HIV-1 protease with an IC50 of 11 nM (similar to CGP 53437). CGP 61755, on the other hand, was c.a. 10-fold more potent (IC50 = 1 nM; similar to saquinavir and indinavir). The selectivity profile of CGP 57813 was comparable to that of CGP 53437 while CGP 61755 clearly had improved selectivity for HIV-1 protease over human aspartic proteases. All three compounds had similar antiviral activity in HIV-1/MN infected MT-2 cells; ED50s were c.a. 5 nM and ED90s were 30 nM. Compared to CGP 53437, both CGP 57813 and CGP 61755 had markedly better bioavailability in mice after oral administration in a DMSO-hydroxypropyl-β-cyclodextrin formulation. However, when CGP 57813 was administered in a sesame oil-based formulation to either mice or dogs no useful plasma concentrations could be measured. In contrast, CGP 61755 was clearly bioavailable in dogs after oral administration of the compound in the same formulation; 1.2 g per dog resulted in a mean AUC0-8 h = 21.06 ± 3.53 μM.h, a mean Cmax = 4.8 ± 0.52 μM and compound was detectable for at least 8 h after administration. The potent antiviral activity of CGP 61755 together with improved selectivity and oral bioavailability holds promise for efficacy in AIDS therapy.

Design and synthesis of HIV-1 protease inhibitors for a long-acting injectable drug application

The design and synthesis of novel HIV-1 protease inhibitors (PIs) (1-22), which display high potency against HIV-1 wild-type and multi-PI-resistant HIV-mutant clinical isolates, is described. Lead optimization was initiated from compound 1, a Phe-Phe hydroxyethylene peptidomimetic PI, and was directed towards the discovery of new PIs suitable for a long-acting (LA) injectable drug application. Introducing a heterocyclic 6-methoxy-3-pyridinyl or a 6-(dimethylamino)-3-pyridinyl moiety (R(3)) at the para-position of the P1' benzyl fragment generated compounds with antiviral potency in the low single digit nanomolar range. Halogenation or alkylation of the metabolic hot spots on the various aromatic rings resulted in PIs with high stability against degradation in human liver microsomes and low plasma clearance in rats. Replacing the chromanolamine moiety (R(1)) in the P2 protease binding site by a cyclopentanolamine or a cyclohexanolamine derivative provided a series of high clearance PIs (16-22) with EC(50)s on wild-type HIV-1 in the range of 0.8-1.8 nM. PIs 18 and 22, formulated as nanosuspensions, showed gradual but sustained and complete release from the injection site over two months in rats, and were therefore identified as interesting candidates for a LA injectable drug application for treating HIV/AIDS.

Macrocyclic peptidomimetic inhibitors of beta-secretase (BACE): first X-ray structure of a macrocyclic peptidomimetic-BACE complex

The synthesis of novel macrocyclic peptidomimetic inhibitors of the enzyme BACE1 is described. These macrocycles are derived from a hydroxyethylene core structure. Compound 7 was co-crystallized with BACE1 and the X-ray structure of the complex elucidated at 1.6 Angstrom resolution. This molecule inhibits the production of the Abeta peptide in HEK293 cells overexpressing APP751sw.