Synthesis and biological evaluation of novel amprenavir-based P1-substituted bi-aryl derivatives as ultra-potent HIV-1 protease inhibitors

Structural and Synthetic Aspects of Small Ring Oxa- and Aza-Heterocyclic Ring Systems as Antiviral Activities

Antiviral properties of different oxa- and aza-heterocycles are identified and properly correlated with their structural features and discussed in this review article. The primary objective is to explore the activity of such ring systems as antiviral agents, as well as their synthetic routes and biological significance. Eventually, the structure-activity relationship (SAR) of the heterocyclic compounds, along with their salient characteristics are exhibited to build a suitable platform for medicinal chemists and biotechnologists. The synergistic conclusions are extremely important for the introduction of a newer tool for the future drug discovery program.

Recent Advances Towards Treatment of HIV: Synthesis and SAR Studies

In the present study, authors want to encourage the research exertions through structureactivity relationship for the identification of effective molecules for the treatment of Human immunodeficiency virus because nowadays AIDS is considered as one of the main causes of death in human beings. A diversity of biological resources has been searched and developed for the treatment of HIV but unfortunately, until now, no medicine is found to be fully effective and safe for the cure of patients. Human immunodeficiency virus is a type of lentivirus which causes the infection of HIV and once it enters the human body, it stays for a longer period of time triggering immunodeficiency syndrome. For searching and developing new potent and effective anti-HIV molecules, medicinal chemists have engaged in countless targets with the structure-activity relationship (SAR) of molecules and on this basis, many antiretroviral therapies have been developed to cure HIV infection. Most of these new searched molecules have been found to be clinically active against various types of AIDS patient and auxiliary research in this area may lead to better treatment in the near future. This article encompasses and highlights the recent advancement of innumerable inhibitors laterally through synthetic, semi-synthetic and structure-activity relationship approaches.

Structure-Based Design of Highly Potent HIV-1 Protease Inhibitors Containing New Tricyclic Ring P2-Ligands: Design, Synthesis, Biological, and X-ray Structural Studies

We describe here design, synthesis, and biological evaluation of a series of highly potent HIV-1 protease inhibitors containing stereochemically defined and unprecedented tricyclic furanofuran derivatives as P2 ligands in combination with a variety of sulfonamide derivatives as P2' ligands. These inhibitors were designed to enhance the ligand-backbone binding and van der Waals interactions in the protease active site. A number of inhibitors containing the new P2 ligand, an aminobenzothiazole as the P2' ligand and a difluorophenylmethyl as the P1 ligand, displayed very potent enzyme inhibitory potency and also showed excellent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The tricyclic P2 ligand has been synthesized efficiently in an optically active form using enzymatic desymmetrization of meso-1,2-(dihydroxymethyl)cyclohex-4-ene as the key step. We determined high-resolution X-ray structures of inhibitor-bound HIV-1 protease. These structures revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insights into the binding properties of these new inhibitors.

Design, synthesis and biological evaluation of HIV-1 protease inhibitors with morpholine derivatives as P2 ligands in combination with cyclopropyl as P1' ligand

A series of novel HIV-1 protease inhibitors has been designed and synthesized, which contained morpholine derivatives as the P2 ligands and hydrophobic cyclopropyl as the P1' ligand at the meantime in this study, with the aim of improving the interactions between the active sites of HIV-1 protease and the inhibitors. Twenty-eight compounds were synthesized and assessed, among which inhibitors m18 and m1 exhibited excellent inhibitory effect on the activity of HIV-1 protease with IC₅₀ value of 47 nM and 53 nM, respectively. The molecular modeling of m1 revealed possible hydrogen bondings or van der Waals between the inhibitor and the protease, worthy of in-depth study.

Design, synthesis, and X-ray studies of potent HIV-1 protease inhibitors incorporating aminothiochromane and aminotetrahydronaphthalene carboxamide derivatives as the P2 ligands

We describe the design, synthesis, and biological evaluation of a series of novel HIV-1 protease inhibitors with carboxamide derivatives as the P2 ligands. We have specifically designed aminothiochromane and aminotetrahydronaphthalene-based carboxamide ligands to promote hydrogen bonding and van der Waals interactions in the active site of HIV-1 protease. Inhibitors 4e and 4j have shown potent enzyme inhibitory and antiviral activity. High resolution X-ray crystal structures of 4d- and 4k-bound HIV-1 protease revealed molecular insights into the ligand-binding site interactions.

Design and Synthesis of Highly Potent HIV-1 Protease Inhibitors Containing Tricyclic Fused Ring Systems as Novel P2 Ligands: Structure-Activity Studies, Biological and X-ray Structural Analysis

The design, synthesis, and biological evaluation of a new class of HIV-1 protease inhibitors containing stereochemically defined fused tricyclic polyethers as the P2 ligands and a variety of sulfonamide derivatives as the P2' ligands are described. A number of ring sizes and various substituent effects were investigated to enhance the ligand-backbone interactions in the protease active site. Inhibitors 5c and 5d containing this unprecedented fused 6-5-5 ring system as the P2 ligand, an aminobenzothiazole as the P2' ligand, and a difluorophenylmethyl as the P1 ligand exhibited exceptional enzyme inhibitory potency and maintained excellent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The umbrella-like P2 ligand for these inhibitors has been synthesized efficiently in an optically active form using a Pauson-Khand cyclization reaction as the key step. The racemic alcohols were resolved efficiently using a lipase catalyzed enzymatic resolution. Two high resolution X-ray structures of inhibitor-bound HIV-1 protease revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insight into the binding properties of these new inhibitors.

BODIPY-based fluorescent liposomes with sesquiterpene lactone trilobolide

Like thapsigargin, which is undergoing clinical trials, trilobolide is a natural product with promising anticancer and anti-inflammatory properties. Similar to thapsigargin, it has limited aqueous solubility that strongly reduces its potential medicinal applications. The targeted delivery of hydrophobic drugs can be achieved using liposome-based carriers. Therefore, we designed a traceable liposomal drug delivery system for trilobolide. The fluorescent green-emitting dye BODIPY, cholesterol and trilobolide were used to create construct 6. The liposomes were composed of dipalmitoyl-3-trimethylammoniumpropane and phosphatidylethanolamine. The whole system was characterized by atomic force microscopy, the average size of the liposomes was 150 nm in width and 30 nm in height. We evaluated the biological activity of construct 6 and its liposomal formulation, both of which showed immunomodulatory properties in primary rat macrophages. The uptake and intracellular distribution of construct 6 and its liposomal formulation was monitored by means of live-cell fluorescence microscopy in two cancer cell lines. The encapsulation of construct 6 into the liposomes improved the drug distribution in cancer cells and was followed by cell death. This new liposomal trilobolide derivative not only retains the biological properties of pure trilobolide, but also enhances the bioavailability, and thus has potential for the use in theranostic applications.

Biocatalysts for the pharmaceutical industry created by structure-guided directed evolution of stereoselective enzymes

Enzymes have been used for a long time as catalysts in the asymmetric synthesis of chiral intermediates needed in the production of therapeutic drugs. However, this alternative to man-made catalysts has suffered traditionally from distinct limitations, namely the often observed wrong or insufficient enantio- and/or regioselectivity, low activity, narrow substrate range, and insufficient thermostability. With the advent of directed evolution, these problems can be generally solved. The challenge is to develop and apply the most efficient mutagenesis methods which lead to highest-quality mutant libraries requiring minimal screening. Structure-guided saturation mutagenesis and its iterative form have emerged as the method of choice for evolving stereo- and regioselective mutant enzymes needed in the asymmetric synthesis of chiral intermediates. The number of (industrial) applications in the preparation of chiral pharmaceuticals is rapidly increasing. This review features and analyzes typical case studies.

Recent Progress in the Development of HIV-1 Protease Inhibitors for the Treatment of HIV/AIDS

HIV-1 protease inhibitors continue to play an important role in the treatment of HIV/AIDS, transforming this deadly ailment into a more manageable chronic infection. Over the years, intensive research has led to a variety of approved protease inhibitors for the treatment of HIV/AIDS. In this review, we outline current drug design and medicinal chemistry efforts toward the development of next-generation protease inhibitors beyond the currently approved drugs.

Recent patents and emerging therapeutics for HIV infections: a focus on protease inhibitors

The inclusion of protease inhibitors (PIs) in highly active antiretroviral therapy has significantly improved clinical outcomes in HIV-1-infected patients. To date, PIs are considered to be the most important therapeutic agents for the treatment of HIV infections. Despite high anti-HIV-1 potency, poor oral bioavailability of PIs has been a major concern. For achieving therapeutic concentrations, large doses of PIs are administered, which results in unacceptable systemic toxicities. Such severe and long-term toxicities necessitate the development of safer and potentially promising PIs. Recently, considerable attention has been paid to the development of newer compounds capable of inhibiting wild-type and resistant HIV-1 protease. Some of these PIs have displayed potent HIV-1 protease inhibitory activity. In this review, we have made an attempt to provide an overview on clinically approved and newly developing PIs, and related recent patents in the development of novel PIs.

The nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and protease inhibitors in the treatment of HIV infections (AIDS)

The majority of the drugs currently used for the treatment of HIV infections (AIDS) belong to either of the following three classes: nucleoside reverse transcriptase inhibitors (NRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors (PIs). At present, there are 7 NRTIs, 5 NNRTIs, and 10 PIs approved for clinical use. They are discussed from the following viewpoints: (i) chemical formulae; (ii) mechanism of action; (iii) drug combinations; (iv) clinical aspects; (v) preexposure prophylaxis; (vi) prevention of mother-to-child transmission; (vii) their use in children; (viii) toxicity; (ix) adherence (compliance); (x) resistance; (xi) new NRTIs, NNRTIs, or PIs in (pre)clinical development; and (xii) the prospects for a "cure" of the disease.