Current Medicinal Chemistry - Volume 22, Issue 37, 2015

The production of superoxide anion radical (O2•-) is essential for the life of aerobic organisms. This free radical acts as a signaling molecule, regulating numerous biological processes including apoptosis, aging, and senescence. Nevertheless, when overproduction of O2•- occurs and/or antioxidant defences are deficient, oxidative stress may develop, damaging important biomolecules and altering their physiological function. These effects have been associated to the development of several diseases. Scavenging of O2•- has been used as a hallmark to test the antioxidant capacity of several types of compounds in cellular and non-cellular systems. However, despite the pathophysiological importance of O2•-, the information about its endogenous and/or chemical generation and detection is dispersed and there are no reports that concisely cover the information in an integrated form. This gap can explain the limitations attributed to the currently used systems, namely in what concerns the selectivity, specificity and validation. This review attempts to provide a critical assessment of the available O2•- generating and detection, both in endogenous and chemical systems, scrutinizing its advantages and limitations in order to facilitate the choice and implementation of the O2•- generator and/or detection method that better fits the researchers’ objectives.

Passage into the brain has always been a major challenge for medicine in order to treat malfunctions of the central nervous system (CNS). The blood-brain-barrier (BBB) is a physical obstacle that controls the entrance of substances -including pharmaceuticals- into the brain. The application of nanotechnology in medicine, namely nanomedicine, is rapidly evolving and opens new prospects for brain imaging and drug delivery into the brain. Nanomedicine when combined with nuclear medicine can offer new, promising and innovative means towards this direction through radiolabeled nanoparticles. Nanoparticles radiolabeled with β-, γ- or β+-emitters can cross the BBB and play major role in CNS imaging and/or drug delivery.

Few selective cyclooxygenase-1 (COX-1) inhibitors have been described up to now, although recent studies underlined the involvement of COX-1 in the carcinogenesis, pathogenesis of neuroinflammation, cardiovascular diseases and pain. Among the known COX-1 inhibitors none proved to be a good drug candidate, with the exception of mofezolac, that is clinically used as an analgesic drug. New selective inhibitors were very often discovered as a minor achievement during SAR investigations to discover selective COX-2 inhibitors (COXIBs). After a recognition of the new COX-1 inhibitors synthesized in the last five years, it was attempted to draw, for each chemical class, a structure which might highlight the determinant molecular features able to switch the selectivity towards the COX-1 isoform. Overall, this review could constitute a tool to a better design of novel selective COX-1 inhibitors, to be used in a disease theranostic approach targeting COX-1.

Human American trypanosomiasis, commonly called Chagas disease, is one of the most neglected illnesses in the world and remains one of the most prevalent chronic infectious diseases of Latin America with thousands of new cases every year. The only treatments available have been introduced five decades ago. They have serious, undesirable side effects and disputed benefits in the chronic stage of the disease – a characteristic and debilitating cardiomyopathy and/or megavisceras. Several laboratories have therefore focused their efforts in finding better drugs. Although recent years have brought new clinical trials, these are few and lack diversity in terms of drug mechanism of action, thus resulting in a weak drug discovery pipeline. This fragility has been recently exposed by the failure of two candidates; posaconazole and E1224, to sterilely cure patients in phase 2 clinical trials. Such setbacks highlight the need for continuous, novel and high quality drug discovery and development efforts to discover better and safer treatments. In this article we will review past and current findings on drug discovery for Trypanosoma cruzi made by academic research groups, industry and other research organizations over the last half century. We also analyze the current research landscape that is now better placed than ever to deliver alternative treatments for Chagas disease in the near future.

Hypoxia in tumor cells is characterized by a lack of oxygen resulting from reduced blood supply to the surrounding tissue, and is a common characteristic of solid tumors as a consequence of rapid cell growth. Hypoxia in tumors is a predictor of both resistance to chemotherapy and of a metastatic/aggressive form of cancer, and as a result, development of cancer therapies which target hypoxia is of vital importance. One such targeting strategy is the development of hypoxia-activated prodrugs (HAP) which can preferentially release chemotherapeutic agents within hypoxic tumor regions. This targeting strategy is accomplished by attaching a hypoxia activated trigger to a chemotherapeutic agent and under oxygen-poor conditions, the agent (effector) is released into the tumor, while remaining intact in normal tissue, and leaving non-hypoxic cells undamaged. Overall, this strategy can achieve an increased therapeutic benefit over conventional small molecule chemotherapeutic treatments by concentrating the drugs within hypoxic tumor environments, while simultaneously reducing the side-effects and toxicity issues that surround the systemic distribution of traditional drugs on normoxic cells. In this review, we will describe the factors that should be considered when designing an effective HAP, such as the mechanism of prodrug action, the elements that influence the rational design of HAP (i.e. reduction potential), and the activating enzymes of HAP. As part of this description, we will utilize select examples from the literature to reinforce these factors, and make a case for the intelligent design of new HAPs, leading to the development of novel hypoxia targeting chemotherapeutic agents.