Current Medicinal Chemistry - Volume 25, Issue 28, 2018

Background: The family of DNA topoisomerases comprises a group of enzymes that catalyse the induction of topological changes to DNA. These enzymes play a role in the cell replication machinery and are, therefore, important targets for anticancer drugs - with human DNA topoisomerase IIα being one of the most prominent. Active compounds targeting this enzyme are classified into two groups with diverse mechanisms of action: DNA poisons act by stabilizing a covalent cleavage complex between DNA and the topoisomerase enzyme, transforming it into a cellular toxin, while the second diverse group of catalytic inhibitors, provides novel inhibition avenues for tackling this enzyme due to frequent occurrence of side effects observed during the DNA poison therapy. Methods: Based on a comprehensive literature search we present an overview of available bioassays and in silico methods in the identification of human DNA topoisomerase IIα inhibitors. Results and Conclusion: A comprehensive outline of the available methods and approaches that explore in detail the in vitro mechanistic and functional aspects of the topoisomerase IIα inhibition of both topo IIα inhibitor groups is presented. The utilized in vitro cell-based assays and in vivo studies to further explore the validated topo IIα inhibitors in subsequent preclinical stages of the drug discovery are discussed. The potential of in silico methods in topoisomerase IIα inhibitor discovery is outlined. A list of practical guidelines was compiled to aid new as well experienced researchers in how to optimally approach the design of targeted inhibitors and validation in the preclinical drug development stages.

There are several mechanisms by which cancer cells develop resistance to treatments, including increasing anti-apoptosis, increasing drug efflux, inducing angiogenesis, enhancing DNA repair and altering cell cycle checkpoints. The drugs are hard to reach curative effects due to these resistance mechanisms. It has been suggested that liposomes based co-delivery systems, which can deliver drugs and genes to the same tumor cells and exhibit synergistic anti-cancer effects, could be used to overcome the resistance of cancer cells. As the co-delivery systems could simultaneously block two or more pathways, this might promote the death of cancer cells by sensitizing cells to death stimuli. This article provides a brief review on the liposomes based co-delivery systems to overcome cancer resistance by the synergistic effects of drugs and genes. Particularly, the synergistic effects of combinatorial anticancer drugs and genes in various cancer models employing multifunctional liposomes based co-delivery systems have been discussed. This review also gives new insights into the challenges of liposomes based co-delivery systems in the field of cancer therapy, by which we hope to provide some suggestions on the development of liposomes based co-delivery systems.

Background: The Renin-Angiotensin System (RAS) is a key regulator of cardiovascular and renal homeostasis, but also plays important roles in mediating physiological functions in the central nervous system (CNS). The effects of the RAS were classically described as mediated by angiotensin (Ang) II via angiotensin type 1 (AT1) receptors. However, another arm of the RAS formed by the angiotensin converting enzyme 2 (ACE2), Ang-(1-7) and the Mas receptor has been a matter of investigation due to its important physiological roles, usually counterbalancing the classical effects exerted by Ang II. Objective: We aim to provide an overview of effects elicited by the RAS, especially Ang-(1-7), in the brain. We also aim to discuss the therapeutic potential for neuropsychiatric disorders for the modulation of RAS. Method: We carried out an extensive literature search in PubMed central. Results: Within the brain, Ang-(1-7) contributes to the regulation of blood pressure by acting at regions that control cardiovascular functions. In contrast with Ang II, Ang-(1-7) improves baroreflex sensitivity and plays an inhibitory role in hypothalamic noradrenergic neurotransmission. Ang-(1-7) not only exerts effects related to blood pressure regulation, but also acts as a neuroprotective component of the RAS, for instance, by reducing cerebral infarct size, inflammation, oxidative stress and neuronal apoptosis. Conclusion: Pre-clinical evidence supports a relevant role for ACE2/Ang-(1-7)/Mas receptor axis in several neuropsychiatric conditions, including stress-related and mood disorders, cerebrovascular ischemic and hemorrhagic lesions and neurodegenerative diseases. However, very few data are available regarding the ACE2/Ang-(1-7)/Mas receptor axis in human CNS.

Cytochrome P450s are enzymes capable of metabolizing a wide variety of drugs. Their significant impact in drug discovery has led to extensive research, computationally and experimentally, in order to explore how a chemical entity responds to metabolizing enzymes. We present an overview of ligand-based and structure-based methodologies, along with pertinent information on the structures, biology, and relevance of these enzymes.

Inflammatory Bowel Diseases (IBD) comprised of two disorders of idiopathic chronic intestinal inflammation that affect about three million people worldwide: Crohn's disease and ulcerative colitis. Nowadays, the first-line of treatment for patients with mild to moderate symptoms of IBD is comprised of corticosteroids, immunosuppressants, antibiotics, and biological agents. Unfortunately, none of these drugs are curative, and their long-term use may cause severe side effects and complications. Almost 40% of IBD patients use alternative therapies to complement the conventional one, and flavonoids are gaining attention for this purpose. The biological properties of flavonoids are well documented and their antioxidant and anti-inflammatory activities have been arousing attention in the scientific community. Flavonoids are the most widely distributed polyphenols in plants and fruits, making part of the human diet. Taking into account that all ingested flavonoids are expected to exert biological actions at the gastrointestinal level, research on the modulatory effect of these compounds in IBD is of paramount importance. This review intends to summarize, in an integrated and comprehensive form, the effect of flavonoids, both in vitro and in vivo, in the different phases of the characteristic IBD inflammatory network.