Current Medicinal Chemistry (v.22, #5)

Meet the Editorial Board: by Chen Chen (551-551).

Redox-active and Redox-silent Compounds: Synergistic Therapeutics in Cancer by M. Tomasetti, L. Santarelli, R. Alleva, Lan-Feng Dong, J. Neuzil (552-568).
Tumours exhibit higher basal levels of reactive oxygen species (ROS) and altered redox environment compared to normal cells. Excessive level of ROS can be toxic to these cells, thus they become more vulnerable to damage by further ROS insults induced by pharmacological agents. However, the upregulation of antioxidant capacity in adaptation to intrinsic oxidative stress in cancer cells can confer drug resistance. Therefore, abrogation of such drugresistant mechanisms by redox modulation could have significant therapeutic implications. Many redox-modulating agents have been developed. The redox-active system epitomised by ascorbate-driven quinone redox cycling, and the group of redox-silent vitamin E analogues represented by α-tocopheryl succinate have been shown to induce selective cancer cell death in different types of cancer. These compounds synergistically act by destabilising organelles like mitochondria, unleashing their apoptogenic potential, which results in efficient death of malignant cells and suppression of tumour growth. Consistent with this notion, clinical trials that aim to examine the therapeutic performance of novel redoxmodulating drugs in cancer patients are currently under way.

Biomedical imaging is an essential tool for diagnosis and therapy of diseases such as cancers. It is likely true that medicine has developed with biomedical imaging methods. Sensitivity and resolution of biomedical imaging methods can be improved with imaging agents. Furthermore, it will be ideal if imaging agents could be also used as therapeutic agents. Therefore, one dose can be used for both diagnosis and therapy of diseases (i.e., theragnosis). This will simplify medical treatment of diseases, and will be also a benefit to patients. Mixed (Ln1xLn2yO3, x + y = 2) or unmixed (Ln2O3) lanthanide (Ln) oxide nanoparticles (Ln = Eu, Gd, Dy, Tb, Ho, Er) are potential multi-modal imaging and cancer therapeutic agents. The lanthanides have a variety of magnetic and optical properties, useful for magnetic resonance imaging (MRI) and fluorescent imaging (FI), respectively. They also highly attenuate X-ray beam, useful for X-ray computed tomography (CT). In addition gadolinium-157 (157Gd) has the highest thermal neutron capture cross section among stable radionuclides, useful for gadolinium neutron capture therapy (GdNCT). Therefore, mixed or unmixed lanthanide oxide nanoparticles can be used for multi-modal imaging methods (i.e., MRI-FI, MRI-CT, CT-FI, and MRICT- FI) and cancer therapy (i.e., GdNCT). Since mixed or unmixed lanthanide oxide nanoparticles are single-phase and solid-state, they can be easily synthesized, and are compact and robust, which will be beneficial to biomedical applications. In this review physical properties of the lanthanides, synthesis, characterizations, multi-modal imagings, and cancer therapy of mixed and unmixed lanthanide oxide nanoparticles are discussed.

This review article is intended to describe how oxidative stress regulates cardiovascular disease development and progression. Epigenetic mechanisms related to oxidative stress, as well as more reliable biomarkers of oxidative stress, are emerging over the last years as potentially useful tools to design therapeutic approaches aimed at modulating enhanced oxidative stress “in vivo”, thereby mitigating the consequent atherosclerotic burden. As a paradigm, we describe the case of obesity, in which the intertwining among oxidative stress, due to caloric overload, chronic low-grade inflammation induced by adipose tissue dysfunction, and platelet activation represents a vicious cycle favoring the progression of atherothrombosis. Oxidative stress is a major player in the pathobiology of cardiovascular disease (CVD). Reactive oxygen species (ROS)- dependent signaling pathways prompt transcriptional and epigenetic dysregulation, inducing chronic low-grade inflammation, platelet activation and endothelial dysfunction. In addition, several oxidative biomarkers have been proposed with the potential to improve current understanding of the mechanisms underlying CVD. These include ROS-generating and/or quenching molecules, and ROS-modified compounds, such as F2-isoprostanes. There is also increasing evidence that noncoding micro- RNA (mi-RNA) are critically involved in post- transcriptional regulation of cell functions, including ROS generation, inflammation, regulation of cell proliferation, adipocyte differentiation, angiogenesis and apoptosis. These molecules have promising translational potential as both markers of disease and site of targeted interventions. Finally, oxidative stress is a critical target of several cardioprotective drugs and nutraceuticals, including antidiabetic agents, statins, renin-angiotensin system blockers, polyphenols and other antioxidants. Further understanding of ROS-generating mechanisms, their biological role as well as potential therapeutic implications would translate into consistent benefits for effective CV prevention.

Glucocorticoids in Patients with Rheumatic Diseases: Friends or Enemies of Bone? by Fedra Ciccarelli, Massimo De Martinis, Lia Ginaldi (596-603).
Increased bone resorption and enhanced risk of osteoporotic fractures are often reported in patients with diseases having immune system involvement, mainly inflammatory rheumatic diseases, for which glucocorticoids are more often prescribed because of their powerful antinflammatory effects. Among secondary osteoporosis, glucocorticoidinduced osteoporosis is the most common and severe form, and up to now prolonged glucocorticoid therapy has been considered the most important osteoporotic risk factor in rheumatic patients. However, it is now clear that the pathogenesis of osteoporosis in inflammatory rheumatic diseases is mediated by several factors. In particular, new discoveries within osteoimmunology concerning the complex relationship between bone and immunity, suggest that inflammation itself, through proinflammatory and osteoclastogenic cytokine overexpression, promotes bone resorption leading to increased skeletal fragility. Therefore, by controlling systemic inflammation, it is also possible to reduce the loss of bone mass which accompanies rheumatic diseases. From this point of view, we critically revisit the effects of glucocorticoids on bone in rheumatic diseases, in which they should be seen not just as an enemy of the bone health but eventually as a potential therapeutic tool capable of reducing the risk of osteoporosis by controlling disease activity and inflammation.

During the last decade, the formulation of nanofibrous materials loaded with different drugs for biomedical applications has evoked considerable interest. The large specific surface area, the special micro- and macrostructure of fiber mats, the possibility for gradual release and site-specific local delivery of the active compounds lead to cytotoxicity decrease and enhancement of the therapeutic effect of drugs and implants. The present review details the different spinning techniques applied for the design of micro- and nanofibrous drug delivery systems. It furthermore deals with the use of various polymers that are capable for the formation of fiber scaffolds of various biomedical applications.

Recent Advances of p53-MDM2 Small Molecule Inhibitors (2011-Present) by Peng-Cheng Lv, Juan Sun, Hai-Liang Zhu (618-626).
P53 is an important transcriptional factor that plays a pivotal role in different biological process (cell cycle, apoptosis, DNA repair, angiogenesis and cellular metabolism). While p53 binds to the promoter and increases the gene expression of Mdm2, MDM2 protein directly binds to p53 and inhibits its activity. Therefore, inhibitor of p53 and MDM2 has been considered as a potential cancer therapeutic agent due to the critical inhibitory role of MDM2 on p53. Small-molecule inhibitor of p53-MDM2 has been designed to serve as an effective way to treat cancer. Several compounds have moved into different phase of clinical trials based on major advances in the development of small-molecule inhibitors in recent years. Since there are few reviews covering the structure- activity relationship analysis of recent p53-MDM2 inhibitors reported from 2011 to the present time, in this review, attentions are focused on the development of p53-MDM2 inhibitors published from 2011 to the present time.

Oxidative Stress in COPD: Molecular Background and Clinical Monitoring by Balazs Antus, Zsuzsanna Kardos (627-650).
Chronic obstructive pulmonary disease (COPD) is a major and rapidly increasing health problem associated with a chronic inflammatory response, predominantly in small airways and lung parenchyma. Oxidative stress induced by reactive oxygen and nitrogen species (ROS and RNS) plays a central role in the pathophysiology of COPD. There is evidence that several molecules formed during oxidative processes may have the potential to serve as biomarkers of oxidative stress in the airways of patients with COPD. Among these molecules carbon monoxide, ethane and pentane can be measured in the exhaled air, while 8-isoprostane, malondialdehyde, 4- hydroxyhexenal, 4-hyroxynonenal, acrolein, hydrogen peroxide, nitrogen oxides and 3-nitrotyrosine can be detected in exhaled breath condensate and/or sputum supernatant. In this review the molecular background of these processes including the formation of ROS and RNS, the biosynthesis of essential ω-3 and ω-6 polyunsaturated fatty acids as building blocks of lipids in the cellular membranes and their enzymatic and non-enzymatic metabolism to eicosanoids and related compounds have been summarized. Moreover, the formation of oxidative stress markers studied most commonly in the context of COPD has been briefly discussed. The associations between biomarkers and clinical variables have also been highlighted in an attempt to illustrate the potential clinical applicability of these biomarker measurements.

In bacterial type II fatty acid biosynthesis (FAS-II), β-ketoacyl-acyl carrier protein (ACP) synthase III (FabH) initiates the first condensation of acyl-CoA and malonyl-ACP to form acetoacetyl-ACP. Its key role for organism survival and specificity to bacteria make it as an essential target for the discovery of novel antibacterial agents. Over the last decade, several structures of FabH from diverse microorganisms have been solved, giving detailed information about the three-dimensional features of the catalytic pocket. This has facilitated the rational design of FabH inhibitors, which provides a framework for future development of antibiotics against multi-drug resistant strains. This review covers recent advances in the biochemical and structural research of FabH and updates the main families of related inhibitors.