New dipeptide isosteres useful for the inhibition of HIV-1 protease

Protease Inhibitors for the Treatment of HIV/AIDS: Recent Advances and Future Challenges

Acquired Immunodeficiency Syndrome (AIDS) is a chronic disease characterized by multiple life-threatening illnesses caused by a retro-virus, Human Immunodeficiency Virus (HIV). HIV infection slowly destroys the immune system and increases the risk of various other infections and diseases. Although, there is no immediate cure for HIV infection/AIDS, several drugs targeting various cruxes of HIV infection are used to slow down the progress of the disease and to boost the immune system. One of the key therapeutic strategies is Highly Active Antiretroviral Therapy (HAART) or ' AIDS cocktail' in a general sense, which is a customized combination of anti-retroviral drugs designed to combat the HIV infection. Since HAART's inception in 1995, this treatment was found to be effective in improving the life expectancy of HIV patients over two decades. Among various classes of HAART treatment regimen, Protease Inhibitors (PIs) are known to be widely used as a major component and found to be effective in treating HIV infection/AIDS. For the past several years, a variety of protease inhibitors have been reported. This review outlines the drug design strategies of PIs, chemical and pharmacological characteristics of some mechanism-based inhibitors, summarizes the recent developments in small molecule based drug discovery with HIV protease as a drug target. Further discussed are the pharmacology, PI drug resistance on HIV PR, adverse effects of HIV PIs and challenges/impediments in the successful application of HIV PIs as an important class of drugs in HAART regimen for the effective treatment of AIDS.

Applications of Click Chemistry in the Development of HIV Protease Inhibitors

Acquired Immunodeficiency Syndrome (AIDS) has been devastating for millions of people around the world. Inhibition of the human immunodeficiency virus (HIV) protease is among the most important approaches for the therapeutic intervention in HIV infection. Since the discovery of the HIV-1 protease, this enzyme has been considered as a key target for the inhibition of viral replication. A large body of research has been done to develop an effective HIV-1 protease inhibitor. There are to date 10 HIV-1 protease inhibitor drugs approved by the Food and Drug Administration (FDA) that have improved the survival and quality of life of HIV infected people. These drugs are prescribed in combination with the reverse transcriptase inhibitors, which is referred to as highly active antiretroviral therapy (HAART). The HIV-1 protease inhibitors play a vital role in HAART. The applications of click chemistry are dispersing in the field of drug discovery. Recently, click chemistry has captured a lot of attention and has become a powerful tool for the synthesis of medicinal skeletons in the discovery of anti-HIV drugs. Click reaction is a well-known method for making carbon-heteroatom-carbon bonds. Click reactions are popular because they are wide in scope, of high yielding, quick to perform, and easy to purify. In this review, we outlined current approaches towards the development of HIV-1 protease inhibitors employing click chemistry.

Epoxide opening in water and screening in situ for rapid discovery of enzyme inhibitors in microtiter plates

A method utilizing the strategy of epoxide opening by amine with water as co-solvent and screening in situ was developed for rapid discovery of protein inhibitors. Using this approach, HIV protease inhibitors with novel P1' residues were identified in our study. This strategy should be applicable for the efficient assembly of diverse compound collections for inhibitors' discovery and optimization in other systems.

Design and synthesis of a novel series of HIV-1 protease inhibitors

The synthesis and the SAR study of novel pseudo symmetric inhibitors of HIV-1 protease are described. Michael addition of amino acid derivatives to vinyl ketones was utilized to derive a potent (nM) series of HIV-1 protease inhibitors.

Novel HIV-protease inhibitors containing beta-hydroxyether and -thioether dipeptide isostere surrogates: modification of the P3 ligand

Studies involving modifications to the P3 position of previously described HIV-protease inhibitors containing beta-hydroxyether and thioether dipeptide isostere replacements led to the discovery of pseudopeptides 8o and 8p with improved antiviral activities.

Viracept (nelfinavir mesylate, AG1343): a potent, orally bioavailable inhibitor of HIV-1 protease

Using a combination of iterative structure-based design and an analysis of oral pharmacokinetics and antiviral activity, AG1343 (Viracept, nelfinavir mesylate), a nonpeptidic inhibitor of HIV-1 protease, was identified. AG1343 is a potent enzyme inhibitor (Ki = 2 nM) and antiviral agent (HIV-1 ED50 = 14 nM). An X-ray cocrystal structure of the enzyme-AG1343 complex reveals how the novel thiophenyl ether and phenol-amide substituents of the inhibitor interact with the S1 and S2 subsites of HIV-1 protease, respectively. In vivo studies indicate that AG1343 is well absorbed orally in a variety of species and possesses favorable pharmacokinetic properties in humans. AG1343 (Viracept) has recently been approved for marketing for the treatment of AIDS.

Bis tertiary amide inhibitors of the HIV-1 protease generated via protein structure-based iterative design

A series of potent nonpeptide inhibitors of the HIV protease have been identified. Using the structure of compound 3 bound to the HIV protease, bis tertiary amide inhibitor 9 was designed and prepared. Compound 9 was found to be about 17 times more potent than 3, and the structure of the protein-ligand complex of 9 revealed the inhibitor binds in an inverted binding mode relative to 3. Examination of the protein-ligand complex of 9 suggested several modifications in the P1 and P1' pockets. Through these modifications it was possible to improve the activity of the inhibitors another 100-fold, highlighting the utility of crystallographic feedback in inhibitor design. These compounds were found to have good antiviral activity in cell culture, were selective for the HIV protease, and were orally available in three animal models.

Potent human immunodeficiency virus type 1 protease inhibitors that utilize noncoded D-amino acids as P2/P3 ligands

Noncoded D-amino acids have been designed to replace the quinaldic amide-asparaginyl moiety (P2/P3 ligand) found in several potent human immunodeficiency virus (HIV) protease inhibitors such as LY289612. The substituted nitrogen, optimally an N-methanesulfonyl moiety, served as a CH2CONH2 (asparagine side chain mimic), while the amino acid side chain became the backbone and P3 ligand of these novel inhibitors. Compounds derived from S-aryl-D-cysteine proved to be potent HIV protease inhibitors which also exhibited potent whole cell antiviral activity. Oxidation of the cysteines to the sulfoxide or sulfone oxidation states resulted in significant improvements in potency. For example, the compound derived from N-(methyl-sulfonyl)-2-S-naphthylcysteine sulfone, 17c, was a 3.5 nM inhibitor of HIV protease which inhibited the spread of virus in MT4 cells with an IC50 = 4.3 nM. Compounds 17c,g,i were found to be orally bioavailable in a rat model.