Design, synthesis, and neuraminidase inhibitory activity of GS-4071 analogues that utilize a novel hydrophobic paradigm

My 50-Plus Years of Academic Research Collaborations with Industry. A Retrospective

A retrospective is presented highlighting the synthesis of selected "first-in-kind" natural products, their synthetic analogues, structure elucidations, and rationally designed bioactive synthetic compounds that were accomplished because of collaborations with past and present pharmaceutical and agrochemical companies. Medicinal chemistry projects involving structure-based design exploiting cocrystal structures of small molecules with biologically relevant enzymes, receptors, and bacterial ribosomes with synthetic small molecules leading to marketed products, clinical candidates, and novel drug prototypes were realized in collaboration. Personal reflections, historical insights, behind the scenes stories from various long-term projects are shared in this retrospective article.

Progress of small molecular inhibitors in the development of anti-influenza virus agents

The influenza pandemic is a major threat to human health, and highly aggressive strains such as H1N1, H5N1 and H7N9 have emphasized the need for therapeutic strategies to combat these pathogens. Influenza anti-viral agents, especially active small molecular inhibitors play important roles in controlling pandemics while vaccines are developed. Currently, only a few drugs, which function as influenza neuraminidase (NA) inhibitors and M2 ion channel protein inhibitors, are approved in clinical. However, the acquired resistance against current anti-influenza drugs and the emerging mutations of influenza virus itself remain the major challenging unmet medical needs for influenza treatment. It is highly desirable to identify novel anti-influenza agents. This paper reviews the progress of small molecular inhibitors act as antiviral agents, which include hemagglutinin (HA) inhibitors, RNA-dependent RNA polymerase (RdRp) inhibitors, NA inhibitors and M2 ion channel protein inhibitors etc. Moreover, we also summarize new, recently reported potential targets and discuss strategies for the development of new anti-influenza virus drugs.

From neuraminidase inhibitors to conjugates: a step towards better anti-influenza drugs?

For the treatment of seasonal flu and possible pandemic infections the development of new anti-influenza drugs that have good bioavailability against a broad spectrum of influenza viruses including the resistant strains is needed. In this review, we summarize previous methods for the structural modification of zanamivir, a potent neuraminidase inhibitor that has rare drug resistance, in order to develop effective anti-influenza drugs. We also report recent research into the design of multivalent zanamivir drugs and bifunctional zanamivir conjugates, some of which have shown better efficacy in animal experiments. As a step towards developing improved antivirals, conjugating anti-influenza drugs with anti-inflammatory agents can improve oral bioavailability and also exert synergistic effect in influenza therapy.

Cyclodidepsipeptides with a promising scaffold in medicinal chemistry

Among the large family of cyclodepsipeptides, the simplest members are the cyclodidepsipeptides which have an ester group and an amide group in the same six-membered ring. To point out the pharmacological potential of this class of compounds, the present article reviews structure, isolation, synthesis and biological properties of the known cyclodidepsipeptides. Synthesis of cyclodidepsipeptides is achieved by two general approaches--by initial formation of the amide bond, or initial formation of the ester bond; and subsequent intermolecular cyclization to cyclodidepsipeptide structure. It is closely related to the condensation and ring-closure strategies applied in the preparation of the larger members of the cyclodepsipeptide family. However, due to synthesis of the smaller heretocycles it allows for the use of more versatile building blocks. There are data on antimicrobial, antioxidant and immunomodulatory activities of cyclodidepsipeptides as well as their inhibitory activities toward α-glucosidase, acyl-CoA:cholesterol acyltransferase, xanthine oxidase and platelet aggregation. Because we have recently found that two 6-(propan-2-yl)-4-methyl-morpholine-2,5-diones, as novel non-purine xanthine oxidase inhibitors, may give promise to be used in the treatment of gout, in this review we have included a study of molecular interactions of the selected cyclodidepsipeptides with xanthine oxidase using idTarget web server. Cyclodidepsipeptides showed promising pharmacological activities and meet all criteria for good solubility and permeability. However, further research of their medical application is necessary. In addition to this, the diversity of natural cyclodidepsipeptides, simplicity for synthesis and convenience for rational drug design indicate the cyclodidepsipeptide as promising scaffold in medicinal chemistry.

Exploring the interactions of unsaturated glucuronides with influenza virus sialidase

A series of C3 O-functionalized 2-acetamido-2-deoxy-Δ⁴-β-D-glucuronides were synthesized to explore noncharge interactions in subsite 2 of the influenza virus sialidase active site. In complex with A/N8 sialidase, the parent compound (C3 OH) inverts its solution conformation to bind with all substituents well positioned in the active site. The parent compound inhibits influenza virus sialidase at a sub-μM level; the introduction of small alkyl substituents or an acetyl group at C3 is also tolerated.

Progress in type II dehydroquinase inhibitors: From concept to practice

Scientists are concerned by an ever-increasing rise in bacterial resistance to antibiotics, particularly in diseases such as malaria, toxoplasmosis, tuberculosis, and pneumonia, where the currently used therapies become progressively less efficient. It is therefore necessary to develop new, safe, and more efficient antibiotics. Recently, the existence of the shikimic acid pathway has been demonstrated in certain parasites such as the malaria parasite. These types of parasites cause more than a million casualties per year, and their effects are particularly strong in people with a compromised immune system such as HIV patients. In such cases it is possible that inhibitors of this pathway could be active against a large variety of microorganisms responsible for the more opportunistic infections in HIV patients. Interest in this pathway has resulted in the development of a wide variety of inhibitors for the enzymes involved. This review covers recent progress made in the development of inhibitors of the third enzyme of this pathway, i.e., the type II dehydroquinase. The X-ray crystal structures of several dehydroquinases (Streptomyces coelicolor, Mycobacterium tuberculosis, etc.) with an inhibitor bound in the active site have recently been solved. These complexes identified a number of key interactions involved in inhibitor binding and have shed light on several aspects of the catalytic mechanism. These crystal structures have also proven to be a useful tool for the design of potent and selective enzyme inhibitors, a feature that will also be discussed.

Chapter 22. Non-HIV antiviral agents

This chapter focuses on non-HIV antiviral agents. The development of antiviral agents to treat non-HIV infections is largely focused on therapies for the treatment of chronic hepatitis infections B and C. Nucleoside analog continue to be the mainstay of Hepatitis B Virus (HBV) therapeutics. The first small molecule inhibitor of Hepatitis C Virus (HCV), the NS3 protease inhibitor BILN-2061, entered phase 2 clinical trials, producing a striking reduction in viral load in treated individuals. The development of the HCV replicon system and its application to screening for antiviral agents provided tangible benefit with the disclosure of mechanistically and structurally diverse HCV inhibitors. Adefovir dipivoxil has been approved in the United States and the European Union for the treatment of HBV, providing a second small molecule antiviral to add to lamivudine (3TC) and the injectable protein IFNα as the only approved agents for treating HBV infection. The chapter also provides details of the inhibitors of hepatitis B and C virus, the inhibitors of simplex virus and human cytomegalovirus, the inhibitors of respiratory viruses and the inhibitors of West Nile virus and Papilloma virus.