Current Medicinal Chemistry (v.23, #42)

Meet Our Editorial Board Member by Ramon Eritja (4717-4717).

Background: Eph receptors play important functions in developmental processes and diseases and among them EphA2 is well known for its controversial role in cancer. Drug discovery strategies are mainly centered on EphA2 extracellular ligand-binding domain however, the receptor also contains a largely unexplored cytosolic Sam (Sterile alpha motif) domain at the C-terminus. EphA2-Sam binds the Sam domain from the lipid phosphatase Ship2 and the first Sam domain of Odin. Sam-Sam interactions may be important to regulate ligand-induced receptor endocytosis and degradation i.e., processes that could be engaged against tumor malignancy.
Methods: We critically analyzed literature related to a) Eph receptors with particular emphasis on EphA2 and its role in cancer, b) Sam domains, c) heterotypic Sam-Sam interactions involving EphA2-Sam.
Results: While literature data indicate that binding of EphA2-Sam to Ship2-Sam should largely generate pro-oncogenic effects in cancer cells, the correlation between EphA2- Sam/Odin-Sam1 complex and the disease is unclear. Recently a few linear peptides encompassing binding interfaces from either Ship2-Sam and Odin-Sam1 have been characterized but failed to efficiently block heterotypic Sam-Sam interactions involving EphA2-Sam due to the lack of a native like fold.
Conclusion: Molecule antagonists of heterotypic EphA2-Sam associations could work as potential anticancer agents or be implemented as tools to further clarify receptor functions and eventually validate its role as a novel target in the field of anti-cancer drug discovery. Due to the failure of linear peptides there is a crucial need for novel approaches, based on cyclic or helical molecules, to target Sam-Sam interfaces.

Background: Renin-angiotensin system (RAS) and its main product Angiotensin II (AngII) are in the focus of the pharmacological industry mainly because of hypertension treatment. Up-regulated RAS is generally associated with cardiovascular diseases and consequent organs injuries. The classic inhibition of RAS is based on the blocking of the type 1 AngII receptors and inhibition of ACE. The concept of the circulating and tissue RAS opens new challenges for the drug targeting. In spite of a big effort invested, in some cases a traditional RAS manipulation is struggling with unwanted side effects and/or resistance to treatment.
Objective: To improve the efficiency of the classic RAS inhibitors specific complications issuing from feed-back circuits inside the RAS have to be elucidated. Moreover, new peptidases identified in the AngII biosynthesis and Angiotensin 1-7/MAS pathways with opposing effects to AngII are tested for the clinical use. The aim of this review is also to bring attention to new tools in RAS manipulation based on the RNA interference (RNAi). RNAi employs small non-coding nucleic acids that interfere with the mRNA translation. The usefulness of this approach has been demonstrated in the treatment of oncological diseases and progress was also made in the field of the cardiovascular medicine.
Conclusion: We suppose that in the near future, in addition to traditional pharmacological tools, RNAi will contribute to the control of RAS and AngII production. RNAi may also be of importance in the manipulation of tissue RAS that is not easily accessible by the traditional chemical substances.

Research onto the pathogenesis of amyotrophic lateral sclerosis (ALS) has obtained notable gene discoveries, although, to date, only progress with regard to treatment has been very modest. Currently ALS is considered a multifactorial disease that presents diverse clinical presentations, ranging from a monogenic inherited disease to an autoimmune pathology, and develops with misfolded protein aggregation and neuroinflammation. An important factor related to ALS pathogenesis is the microglial activation associated with degenerative motor neurons. This activation leads to changes in the expression of a wide range of genes related to phagocytosis and inflammation, and to profound modifications in the dynamic interactions between neurons and glial cells. Overactivation and deregulation of microglial activity causes deleterious effects and leads to neuronal death. However, the involvement of microglia in non-inflammatory functions challenges our concept of neuroinflammation and opens up new possibilities for the study of the pathophysiological mechanisms of ALS. In this review we summarize the current knowledge on the adaptive interactions between neurons and microglia in ALS. We also discuss the hypothesis that controlling the extent of microglial activation and neuroinflammation may have clinical and therapeutic benefits for the condition.

Anti-influenza Virus Effects of Catechins: A Molecular and Clinical Review by Kazuke Ide, Yohei Kawasaki, Koji Kawakami, Hiroshi Yamada (4773-4783).
Influenza infection and associated epidemics represent a serious public health problem. Several preventive and curative measures exist against its spread including vaccination and therapeutic agents such as neuraminidase inhibitors (e.g., oseltamivir, zanamivir, as well as peramivir and laninamivir, which are licensed in several countries) and adamantanes (e.g., amantadine and rimantadine). However, neuraminidase inhibitor- and adamantane- resistant viruses have been detected, whereas vaccines exhibit strain-specific effects and are limited in supply. Thus, new approaches are needed to prevent and treat influenza infections. Catechins, a class of polyphenolic flavonoids present in tea leaves, have been reported as potential anti-influenza virus agents based on experimental and clinical studies. (?)-epigallocatechin gallate (EGCG), a major and highly bioactive catechin, is known to inhibit influenza A and B virus infections in Madin-Darby canine kidney cells. Additionally, EGCG and other catechin compounds such as epicatechin gallate and catechin-5-gallate also show neuraminidase inhibitory activities as demonstrated via molecular docking. These catechins can bind differently to neuraminidase and might overcome known drug resistancerelated virus mutations. Furthermore, the antiviral effects of chemically modified catechin derivatives have also been investigated, and future structure-based drug design studies of catechin derivatives might contribute to improvements in influenza prevention and treatment. This review briefly summarizes probable mechanisms underlying the inhibitory effects of tea catechins against influenza infection and their clinical benefits on influenza prevention and treatment. Additionally, the great potential of tea catechins and their chemical derivatives as effective antiviral agents is described.

Synthesis of Pyrido-annelated Diazepines, Oxazepines and Thiazepines by Koen Muylaert, Martyna Jatczak, Sven Mangelinckx, Christian V. Stevens (4784-4823).
The immense amount of research on benzodiazepines resulted in the synthesis of heterocycle-fused diazepine derivatives with potential pharmacological activity. Pyridoazepines are recognized to be active in the central nervous system and have a comparable activity to the well-known benzodiazepines. This makes the synthesis and the study of pyridodiazepines an important research topic. This review comprises of the synthesis and activity of pyridodiazepines, pyridooxazepines and pyridothiazepines. Although these structures have a great similarity with benzodiazepines, much less work has been published on their synthesis or derivatization. Therefore, there is a need to further develop these classes of underexplored scaffolds, in search for new chemistry, new methodology and hence new biological features.