Showing papers in "Current Medicinal Chemistry in 2015"

Inflammatory Responses in Brain Ischemia

Abstract: Brain infarction causes tissue death by ischemia due to occlusion of the cerebral vessels and recent work has shown that post stroke inflammation contributes significantly to the development of ischemic pathology. Because secondary damage by brain inflammation may have a longer therapeutic time window compared to the rescue of primary damage following arterial occlusion, controlling inflammation would be an obvious therapeutic target. A substantial amount of experimentall progress in this area has been made in recent years. However, it is difficult to elucidate the precise mechanisms of the inflammatory responses following ischemic stroke because inflammation is a complex series of interactions between inflammatory cells and molecules, all of which could be either detrimental or beneficial. We review recent advances in neuroinflammation and the modulation of inflammatory signaling pathways in brain ischemia. Potential targets for treatment of ischemic stroke will also be covered. The roles of the immune system and brain damage versus repair will help to clarify how immune modulation may treat stroke.

Bacteriophages and phage-derived proteins--application approaches.

Abstract: Currently, the bacterial resistance, especially to most commonly used antibiotics has proved to be a severe therapeutic problem. Nosocomial and community-acquired infections are usually caused by multidrug resistant strains. Therefore, we are forced to develop an alternative or supportive treatment for successful cure of life-threatening infections. The idea of using natural bacterial pathogens such as bacteriophages is already well known. Many papers have been published proving the high antibacterial efficacy of lytic phages tested in animal models as well as in the clinic. Researchers have also investigated the application of non-lytic phages and temperate phages, with promising results. Moreover, the development of molecular biology and novel generation methods of sequencing has opened up new possibilities in the design of engineered phages and recombinant phage-derived proteins. Encouraging performances were noted especially for phage enzymes involved in the first step of viral infection responsible for bacterial envelope degradation, named depolymerases. There are at least five major groups of such enzymes - peptidoglycan hydrolases, endosialidases, endorhamnosidases, alginate lyases and hyaluronate lyases - that have application potential. There is also much interest in proteins encoded by lysis cassette genes (holins, endolysins, spanins) responsible for progeny release during the phage lytic cycle. In this review, we discuss several issues of phage and phage-derived protein application approaches in therapy, diagnostics and biotechnology in general.

Insights into the Mechanisms Involved in the Expression and Regulation of Extracellular Matrix Proteins in Diabetic Nephropathy.

Abstract: Diabetic Nephropathy (DN) is believed to be a major microvascular complication of diabetes. The hallmark of DN includes deposition of Extracellular Matrix (ECM) proteins, such as, collagen, laminin and fibronectin in the mesangium and renal tubulo-interstitium of the glomerulus and basement membranes. Such an increased expression of ECM leads to glomerular and tubular basement membranes thickening and increase of mesangial matrix, ultimately resulting in glomerulosclerosis and tubulointerstitial fibrosis. The characteristic morphologic glomerular mesangial lesion has been described as Kimmelstiel-Wilson nodule, and the process at times is referred to as diabetic nodular glomerulosclerosis. Thus, the accumulation of ECM proteins plays a critical role in the development of DN. The relevant mechanism(s) involved in the increased ECM expression and their regulation in the kidney in diabetic state has been extensively investigated and documented in the literature. Nevertheless, there are certain other mechanisms that may yet be conclusively defined. Recent studies demonstrated that some of the new signaling pathways or molecules including, Notch, Wnt, mTOR, TLRs and small GTPase may play a pivotal role in the modulation of ECM regulation and expression in DN. Such modulation could be operational for instance Notch through Notch1/Jagged1 signaling, Wnt by Wnt/β- catenin pathway and mTOR via PI3-K/Akt/mTOR signaling pathways. All these pathways may be critical in the modulation of ECM expression and tubulo-interstitial fibrosis. In addition, TLRs, mainly the TLR2 and TLR4, by TLR2- dependent and TGF-β-dependent conduits, may modulate ECM expression and generate a fibrogenic response. Small GTPase like Rho, Ras and Rab family by targeting relevant genes may also influence the accumulation of ECM proteins and renal fibrosis in hyperglycemic states. This review summarizes the recent information about the role and mechanisms by which these molecules and signaling pathways regulate ECM synthesis and its expression in high glucose ambience in vitro and in vivo states. The understanding of such signaling pathways and the molecules that influence expression, secretion and amassing of ECM may aid in developing strategies for the amelioration of diabetic nephropathy.

Protective Effects of Melatonin and Mitochondria-targeted Antioxidants Against Oxidative Stress: A Review

Abstract: Oxidative damage is related to aging and a wide range of human disorders. Mitochondria are in large part responsible for free radical production and they are also main targets of the attack of these toxic molecules. The resulting deleterious effects of the damage to mitochondria can be prevented by antioxidants. Melatonin is an endogenously-produced indoleamine that modulates numerous functions, including mitochondria-related functions; this result from its capacity to penetrate all morphophysiological barriers and to enter all subcellular compartments due to its amphiphilic nature. Furthermore, this indoleamine and its metabolites are powerful antioxidants and scavengers of free radicals, protecting cellular membranes, the electron transport chain and mitochondrial DNA from oxidative damage. These properties may make melatonin a potent protector against a variety of free radical-related diseases. By comparison, other conventional antioxidants have less efficacy due to their limited access to the mitochondria. In recent years, research has focused on the advancement of mitochondria-targeted antioxidants, such as MitoQ (composed by the lipophilic triphenylphosphonium cation conjugated to the endogenous antioxidant coenzyme Q10) and MitoE (composed by the triphenylphosphonium cation attached to the antioxidant α-tocopherol). Mitochondria-targeted antioxidants accumulate in several hundred-fold greater concentrations within mitochondria and protect these critical organelles from oxidative damage. Melatonin also seems to be a mitochondria-targeted antioxidant and has similar protective actions as the synthetic antioxidants. Further work is required to determine the therapeutic properties of these antioxidants in ameliorating diseases related to mitochondrial dysfunction.

Quercetin in Cancer Treatment, Alone or in Combination with Conventional Therapeutics?

Abstract: Cancer is a problem of global importance, since the incidence is increasing worldwide and therapeutic options are generally limited. Thus, it becomes imperative to find new therapeutic targets as well as new molecules with therapeutic potential for tumors. Flavonoids are polyphenolic compounds that may be potential therapeutic agents. Several studies have shown that these compounds have a higher anticancer potential. Among the flavonoids in the human diet, quercetin is one of the most important. In the last decades, several anticancer properties of quercetin have been described, such as cell signaling, pro-apoptotic, anti-proliferative and anti-oxidant effects, growth suppression. In fact, it is now well known that quercetin has diverse biological effects, inhibiting multiple enzymes involved in cell proliferation, as well as, in signal transduction pathways. On the other hand, there are also studies reporting potential synergistic effects when combined quercetin with chemotherapeutic agents or radiotherapy. In fact, several studies which aim to explore the anticancer potential of these combined treatments have already been published, the majority with promising results. Actually it is well known that quercetin can act on the chemosensitization and radiosensitization but also as chemoprotective and radioprotective, protecting normal cells of the side effects that results from chemotherapy and radiotherapy, which obviously provides notable advantages in their use in anticancer treatment. Thus, all these data indicate that quercetin may have a key role in anticancer treatment. In this context, this review is focused on the relationship between flavonoids and cancer, with special emphasis on the role of quercetin.

Heterocyclic N-Oxides - An Emerging Class of Therapeutic Agents.

Abstract: Heterocyclic N-oxides have emerged as potent compounds with anticancer, antibacterial, antihypertensive, antiparasitic, anti-HIV, anti-inflammatory, herbicidal, neuroprotective, and procognitive activities. The N-oxide motif has been successfully employed in a number of recent drug development projects. This review surveys the emergence of this scaffold in the mainstream medicinal chemistry with a focus on the discovery of the heterocyclic N-oxide drugs, N-oxide-specific mechanisms of action, drug-receptor interactions and synthetic avenues to these compounds. As the first review on this subject that covers the developments since 1950s to date, it is expected that it will inspire wider implementation of the heterocyclic N-oxide motif in the rational design of new medicinal agents.

Insights on Antimicrobial Resistance, Biofilms and the Use of Phytochemicals as New Antimicrobial Agents

Abstract: Antimicrobial resistance is one of the most serious public health problems. This is of particular concern when bacteria become resistant to various antimicrobial agents simultaneously and when they form biofilms. Consequently, therapeutic options for the treatment of infections have become limited, leading frequently to recurrent infections, treatment failure and increase of morbidity and mortality. Both, persistence and spread of antibiotic resistance, in combination with decreased effectiveness and increased toxicity of current antibiotics have emphasized the urgent need to search alternative sources of antimicrobial substances. Plants are recognized as a source of unexplored chemical structures with high therapeutic potential, including antimicrobial activity against clinically important microorganisms. Additionally, phytochemicals (plant secondary metabolites) present several advantages over synthetic molecules, including green status and different mechanisms of action from antibiotics which could help to overcome the resistance problem. In this study, an overview of the main classes of phytochemicals with antimicrobial properties and their mode of action is presented. A revision about the application of phytochemicals for biofilm prevention and control is also done. Moreover, the use of phytochemicals as scaffolds of new functional molecules to expand the antibiotics pipeline is reviewed.

Antimicrobial Photosensitizers: Drug Discovery Under the Spotlight.

Abstract: Although photodynamic therapy (PDT) was discovered over a hundred years ago by its ability to destroy microorganisms, it has been developed mainly as a cancer therapy. In recent years, due to the inexorable rise in multi-antibiotic resistant strains of pathogens, PDT is being considered as a versatile antimicrobial approach to which microbial cells will not be able to develop resistance. The goal of this review is to survey the different classes of chemical compounds that have been tested as antimicrobial photosensitizers. Some of these compounds have been known for many years, while others have been rationally designed based on recently discovered structural principles. Tetrapyrrole-based compounds (some of which are approved as cancer therapies) that efficiently generate singlet oxygen are more efficient and broad-spectrum when they bear cationic charges, As the macrocycle structure moves from porphyrins to chlorins to phthalocyanines to bacteriochlorins the long wavelength absorption moves to the near-infrared where tissue penetration is better. Four main types of natural products have been tested: curcumin, riboflavin, hypericin and psoralens. Phenothiazinium dyes, such as methylene blue and toluidine blue, have been tested, and some are clinically approved. A variety of non-phenothiazinium dyes with xanthene, triarylmethane and indocyanine structures have also been tested. New ring structures based on BODIPY, squaraine and fullerene cages can also mediate antimicrobial PDT. Finally the process of photocatalysis using titanium dioxide can also have medical uses. Designing new antimicrobial photosensitizers is likely to keep chemists engaged for a long time to come.

Tubulin colchicine binding site inhibitors as vascular disrupting agents in clinical developments.

Abstract: Tumor vasculature is an important target in cancer treatment. Two distinct vasculartargeting therapeutic strategies are applied to attack cancer cells indirectly. The antiangiogenic approach intervenes in the neovascularization processes and blocks the formation of new blood vessels, while th e antivascular approach targets the established tumor blood vessels, making vascular shutdown and resulting in rapid haemorrhagic necrosis and tumor cell death. A number of compounds with diverse structural scaffolds have been designed to target tumor vasculature and they are called vascular disrupting agents (VDAs). The biological or ligand-directed VDAs utilize antibodies, peptides or growth factors to deliver toxins or pro-coagulants or proapoptotic affectors to tumor-related blood vessels, while the small-molecule VDAs selectively target tumor blood vessels and have little effects on the normal endothelium. Among the small-molecule VDAs, the tubulin colchicine binding site inhibitors have been extensively studied and many of them have entered the clinical trials, including CA-4P, CA-1P, AVE8062, OXi4503, CKD-516, BNC105P, ABT-751, CYT- 997, ZD6126, NPI-2358, MN-029 and EPC2407. This review makes a summary of the small-molecule VDAs in clinical developments and highlights some potential VDA leads or candidates for the treatment of tumors.

Potential role of natural compounds against skin aging.

Abstract: Skin aging is an inevitable biological phenomenon of human life. Advancing age brings changes to all components of the integumentary system with consequent signs on the skin. Skin aging is mainly due to intrinsic (chronologic) and extrinsic aging (photo-aging). Photo-aging is a consequence of exposure to ultraviolet radiations. Despite variable economic conditions, the skin care market based on natural products continues to see strong growth. In this context, the research of naturally occurring anti-aging agents is greatly expanding and in recent years numerous plant-derived products have been investigated. This review article focuses on highlighting recent advances in current knowledge on anti-aging natural products grouped and presented according to their family origin. Plants from 35 families were reviewed. A variety of phytomolecules, derived in particular from polyphenols, triterpenes and sterols classes, demonstrated a promising activity. Among them carnosic acid, curculigoside, curcumin, glycyrrhizic acid, mangiferin, mirkoin, asiaticoside, rosmarinic acid, tectorigenin, tyrosol etc., able to inhibit tyrosinase, hyaluronidase, elastase, and collagenase, to scavenge free radicals from skin cells, to prevent trans-epidermal water loss, and to contribute to protect skin from wrinkles, were largely investigated and herein discussed. Extracts and pure compounds from Fabaceae, Asperaceae and Zingiberaceae families have shown particular interest and appear most promising in the development of anti-aging products.

Oxidative Stress Drivers and Modulators in Obesity and Cardiovascular Disease: From Biomarkers to Therapeutic Approach

Abstract: 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 F 2 -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.

Antimicrobial peptides as an opportunity against bacterial diseases.

Abstract: Antimicrobial peptides (AMPs) are an heterogeneous group of small amino acidic molecules produced by the innate immune system of a variety of organisms encompassing all orders of life from eukaryotes to amphibians, insects and plants. Numerous AMPs have been isolated from natural sources and many others have been de novo designed and synthetically produced. AMPs have antimicrobial activity in the micromolar range and compared with traditional antibiotics, they kill bacteria very rapidly. They act, principally, by the electrostatic attraction to negatively charged bacterial cells and consequently membrane disruption, but their antibacterial activity may also involve interference with metabolic processes or different cytoplasmic targets. AMPs are a group of unique and incredible compounds that may be directed to a therapeutic use either alone or in combination with existing antibiotics.

Non-viral Delivery Systems for the Application in p53 Cancer Gene Therapy.

Abstract: A key barrier to the development of gene therapy remains the lack of safe, efficient and easily controllable vehicles for gene delivery. The fundamental problems associated with the viral vehicles, e.g. lack of specificity and immunogenic potential, have driven the development of non-viral systems of gene delivery. In the last decade, studies on p53 gene replacement therapy have dominated the literature. Although clinical trials of p53 gene therapy have achieved limited success, it remains the only tumor suppressor gene to be evaluated formally in clinical trials for cancer treatment, with increasing focus on delivery using non-viral systems. In this article, we particularly review current investigations on p53 gene delivery using non-viral methods, including both physical and chemical approaches, with an emphasis on the latter. The existing opportunities and challenges for successful p53 cancer gene therapy are also discussed.

Physiopathological roles of P2X receptors in the central nervous system.

Abstract: Potent actions of ATP in the central nervous system (CNS) were reported in the late 1940's, but cloning and characterisation of receptors for purines and pyrimidines did not take place until the early 1990's, which identified seven P2X ion channel receptor subtypes, three of which form the cation channel as homomultimers or heteromultimers. P2X receptor subtypes are widely expressed in the CNS and their distribution is described in different regions. They function in synaptic cotransmission and neuromodulation, as well as in trophic signalling. ATP released from nerves and astroglial cells are predominantly involved in neuron-glial interactions. Purinergic signalling is involved in normal behaviour, including learning and memory, sleep and arousal, locomotor and feeding activities and cognition. P2X receptors participate in CNS pathophysiology, including injury, inflammation, Alzheimer's and Parkinson's diseases, multiple sclerosis and amyotrophic lateral sclerosis, depression and anxiety. P2X4 and P2X7 receptor antagonists are effective via microglia against neuropathic pain, while P2X3 receptor antagonists also reduce neuropathic pain, but via a different mechanism.

Fourier Transform Infrared Spectroscopy (FTIR) as a Tool for the Identification and Differentiation of Pathogenic Bacteria

Abstract: Methods of human bacterial pathogen identification need to be fast, reliable, inexpensive, and time efficient. These requirements may be met by vibrational spectroscopic techniques. The method that is most often used for bacterial detection and identification is Fourier transform infrared spectroscopy (FTIR). It enables biochemical scans of whole bacterial cells or parts thereof at infrared frequencies (4,000-600 cm -1 ). The recorded spectra must be subsequently transformed in order to minimize data variability and to amplify the chemically-based spectral differences in order to facilitate spectra interpretation and analysis. In the next step, the transformed spectra are analyzed by data reduction tools, regression techniques, and classification methods. Chemometric analysis of FTIR spectra is a basic technique for discriminating between bacteria at the genus, species, and clonal levels. Examples of bacterial pathogen identification and methods of differentiation up to the clonal level, based on infrared spectroscopy, are presented below.

Curcumin: A Natural Lead for Potential New Drug Candidates

Abstract: Curcumin (1) is a secondary metabolite of turmeric, derived from Curcuma longa L. and was shown to have many biological activities. One of the most interesting properties of curcumin (1) is the antitumour activity allied with the ability to act as a multidrug resistance (MDR) modulator. Several curcumin derivatives have been synthesized with the purpose of discovering more information about the mechanisms of action, to establish structure-activity relationships (SAR), and to overcome pharmacokinetic problems. Over the past few decades, more potent and more stable curcumin derivatives have emerged with potential as drug candidates. Some important SAR studies pointed out that the unstable α,β-unsaturated diketone linker present in curcumin (1) may not be necessary for the antitumour activity; generally, shorter linkers result in more potent compounds than curcumin (1); the type of substituents and their substitution pattern are crucial regarding the biological activities of interest. Overall, the structure of curcumin (1) may represent an important basis for the development of more effective therapeutic agents, particularly in chemotherapy, as reflected by ongoing clinical trials. This article aims to review the synthesis and biological activities of curcumin (1) and derivatives, highlighting the MDR modulation properties of curcumin (1), since these effects makes this natural product a promising lead compound for the development of new anticancer drugs.

Catalpol: A Potential Therapeutic for Neurodegenerative Diseases

Abstract: Neurodegenerative disorders, e.g., Alzheimer’s disease (AD) and Parkinson’s disease (PD) are characterized by the progressive loss of neurons and subsequent cognitive decline. They are mainly found in older populations. Due to increasing life expectancies, the toll inflicted upon society by these disorders continues to become heavier and more prominent. Despite extensive research, however, the exact etiology of these disorders is still unknown, though the pathophysiological mechanisms have been attributed to oxidative, inflammatory and apoptotic injury in the brain. Moreover, there is currently no promising therapeutic agent against these neurodegenerative changes. Catalpol, an iridoid glucoside contained richly in the roots of the small flowering plant species Rehmannia glutinosa Libosch, has been shown to have antioxidation, anti-inflammation, anti-apoptosis and other neuroprotective properties and plays a role in neuroprotection against hypoxic/ischemic injury, AD and PD in both in vivo and in vitro models. It may therefore represent a potential therapeutical agent for the treatment of hypoxic/ischemic injury and neurodegenerative diseases. Based on our studies and those of others in the literature, here we comprehensively review the role of Catalpol in neuroprotection against pathological conditions, especially in neurodegenerative states and the potential mechanisms involved.

P2X receptors and inflammation.

Abstract: Until recently, P2X receptors have not received much attention in the context of immunology and inflammation. While this is justified to a certain extent for P2X1, P2X2, P2X3, P2X5 and P2X6, which still await identification of a convincing role in the pathophysiology of immune cells, it is clearly not any more the case for P2X4 and even more so for P2X7, a molecule that has achieved the status of an essential, nonredundant, immunomodulatory receptor. In this review I will highlight the most important inflammatory responses participated by P2X receptors.

Oxazolidinones as Anti-tubercular Agents: Discovery, Development and Future Perspectives

Abstract: TB drug development pipeline represents varied structural classes of molecules. Oxazolidinones represent synthetic anti-bacterial agents with unique mechanism of action having wide spectrum of activity, oral bioavailability and well established SAR. They act by inhibiting translation at the initiation phase of protein synthesis. Linezolid was the first oxazolidinone to reach the market in the year 2000 for the treatment of methicillin-resistant staphylococcal and vancomycin-resistant enterococcal infections. Oxazolidinones have shown very good anti-mycobacterial activities. Several oxazolidinones are currently in development for their possible use in TB therapy. Oxazolidinones are classified on the basis of C-ring modifications. DuP-721 was the first oxazolidinone having good anti-TB activity. Linezolid, sutezolid and AZD5847 are in clinical development. Several other C-ring modifications have shown promising results. The usefulness of these oxazolidinones in the drug resistant TB is already established. Toxicity, especially myelosuppression, has been an important limiting factor for their development.

Unfolded Protein Response and PERK Kinase as a New Therapeutic Target in the Pathogenesis of Alzheimer’s Disease

Abstract: Recent evidence suggests that the development of Alzheimer's disease (AD) and related cognitive loss is due to mutations in the Amyloid Precursor Protein (APP) gene on chromosome 21 and increased activation of eukaryotic translation initiation factor-2α (eIF2α) phosphorylation. The high level of misfolded and unfolded proteins loading in Endoplasmic Reticulum (ER) lumen triggers ER stress and as a result Unfolded Protein Response (UPR) pathways are activated. Stress-dependent activation of the protein kinase RNA-like endoplasmic reticulum kinase (PERK) leads to the significant elevation of phospho-eIF2α. That attenuates general translation and, on the other hand, promotes the preferential synthesis of Activating Transcription Factor 4 (ATF4) and secretase β (BACE1) - a pivotal enzyme responsible for the initiation of the amyloidogenic pathway resulting in the generation of the amyloid β (Aβ) variant with high ability to form toxic senile plaques in AD brains. Moreover, excessive, long-term stress conditions may contribute to inducing neuronal death by apoptosis as a result of the overactivated expression of pro-apoptotic proteins via ATF4. These findings allow to infer that dysregulated translation, increased expression of BACE1 and ATF4, as a result of eIF2α phosphorylation, may be a major contributor to structural and functional neuronal loss resulting in memory impairment. Thus, blocking PERK-dependent eIF2α phosphorylation through specific, small-molecule PERK branch inhibitors seems to be a potential treatment strategy for AD individuals. That may contribute to the restoration of global translation rates and reduction of expression of ATF4 and BACE1. Hence, the treatment strategy can block accelerated β -amyloidogenesis by reduction in APP cleaving via the BACE1-dependent amyloidogenic pathway.

Chalcones as Promising Lead Compounds on Cancer Therapy

Abstract: Chalcones constitute a group of phenolic compounds that command an increasing interest on cancer research. Natural chalcones are widespread through the plant kingdom. The most abundant and investigated chalcones are isoliquiritigenin, flavokawain and xanthohumol, which are present in the Fabaceae, Piperaceae, Cannabaceae, and Moraceae families. These chalcones have been shown to be promising lead antitumor-chemopreventive drugs by three different activities: antioxidants, cytotoxic and apoptosis inducers. In the recent years, SAR (structure-activity relationship) has contributed towards the improvement of anticancer properties of chalcones by substituting aryl rings and introducing heterocyclic moieties. This review summarizes the anticancer activities shown by natural chalcones and the SAR and describes how different chemical moiety modifications could lead them to be therapeutically useful in the treatment of cancer.

Oleanolic acid and related triterpenoids from olives on vascular function: molecular mechanisms and therapeutic perspectives.

Abstract: Oleanolic acid and related triterpenoids from olives modulate different signaling pathways, showing a wide range of pharmacological activities against inflammation, cancer or cardiovascular diseases. In particular, emerging evidences reveal the potential of oleanolic acid to restore vascular disorders associated to cardiovascular risk factors, i.e. hypertension, obesity and diabetes, and atherosclerosis. During the previous years, in vitro and in vivo studies with these triterpenoids have positioned them as being mainly responsible for cardiovascular risk protection traditionally associated to olive oil. This review updates recent investigations in olive oil triterpenoids function related to cardiovascular diseases, as well as the underlying mechanisms and structural implications. Important aspects of olive oil triterpenoids such as bioavailability and clinical perspectives on cardiovascular disorder are also extensively analyzed. All these investigations evidence the potential of triterpenoids from olive oil as a promising therapeutic strategy against vascular function, thus efficiently preventing the progression of cardiovascular diseases.

Multi-kinase inhibitors.

Abstract: The limitations of many mono-kinase inhibitors can be overcome by agents with multi-target action. An important advantage of targeting more than one kinase, is an increase in potency, due to the synergistic effect. Moreover, this approach can reduce the possibility of developing drug resistance. Several multitarget agents have been designed as single kinase inhibitors and found to be multi-target inhibitors because of the structural homology among the ATP-binding site of kinases. In other cases, these inhibitors have been obtained by optimization of potent individual inhibitors or by combination of selective ligands. Also some irreversible inhibitors act on different kinases and covalently modify the cysteine residues located near the ATP-binding pocket. In this review the most recent examples of multi-kinase inhibitors are reported, focusing on chemical structures, structure-activity relationship (SAR) and biological activity. These inhibitors, suitably substituted, could be used in designing other multitarget agents. Virtual molecular docking would suggest potential targets of molecules, moreover combining pharmacophore combination and screening methods could probably help in the discovery of more potent multikinase inhibitors.

Flavonoids and Dementia: An Update

Abstract: Dementia is a strongly age-related syndrome due to cognitive decline that can be considered a typical example of the combination of physiological and pathological aging-associated changes occurring in old people; it ranges from intact cognition to mild cognitive impairment, which is an intermediate stage of cognitive deterioration, and dementia. The spread of this syndrome has induced to study and try to reduce dementia modifiable risk factors. They include insulin resistance and hyperinsulinaemia, high blood pressure, obesity, smoking, depression, cognitive inactivity or low educational attainment as well as physical inactivity and incorrect diet, which can be considered one of the most important factors. One emerging strategy to decrease the prevalence of mild cognitive impairment and dementia may be the use of nutritional interventions. In the last decade, prospective data have suggested that high fruit and vegetable intakes are related to improved cognitive functions and reduced risks of developing a neurodegenerative process. The protective effects against neurodegeneration could be in part due to the intake of flavonoids that have been associated with several health benefits such as antioxidant and anti-inflammatory activities, increased neuronal signaling, and improved metabolic functions. The present article is aimed at reviewing scientific studies that show the protective effects of flavonoid intake against mild cognitive impairment and dementia.

Microglial Activation as a Compelling Target for Treating Acute Traumatic Brain Injury

Abstract: Microglia and several inflammatory cytokines and neurotrophic growth factors are involved in traumatic brain injury (TBI). Tumor necrosis factor-alpha (TNF-α) can be released by microglia, astrocytes, and neurons. TNF-α has been reported to be both proneurogenic and antineurogenic, depending upon the model, method, and cell-derived region. There are two subtypes of microglia: M1 and M2. The former (or M1 subtype of non-phagocytic microglia) is able to secrete higher levels of TNF-α but lower levels of interleukin (IL)-10 (IL-10), an anti-inflammatory cytokine. Both the proinflammatory and the pro-apoptotic function can also be promoted by activation of tumor necrosis factor-receptor 1 (TNF-R1). In contrast, M2 activation produces lower levels of TNF-α but higher levels of IL-10. Pro-growth and survival pathways can be promoted by the activation of TNFR2. During the acute stage of TBI, both M1 subtype of microglia and TNF-R1 are activated to cause higher levels of TNF-α but lower levels of IL-10, which lead to suppressed neurogenesis, neuronal loss and organ dysfunction (so-called microglial activation I). In contrast, activation of both M2 subtype of microglia and TNF-R2 is able to promote neurogenesis and tissue recovery (so-called microglial activation II). The severity of TBI depends upon the net effects between microglial activation I and microglial activation II. Indeed, by using rodent models of TBI, therapeutic evaluation studies reveal that several agents or strategies attenuate contused brain volume and neurological deficits by inhibiting microglial activation I but inducing microglial activation II. For example, etanercept therapy might attenuate contused brain volume and neurological deficits by inactivating the M1 subtype and TNF-R1 to reduce the microglial activation I response, but it might promote neurogenesis and functional recovery by activating the M2 subtype and TNF-R2. Therefore, based on microglial responses I and II, we conclude that future studies should focus on multiple therapeutic agents and strategies for optimal TBI therapy.

Factors Promoting Tamoxifen Resistance in Breast Cancer via Stimulating Breast Cancer Stem Cell Expansion.

Abstract: Estrogen receptor-alpha positive (ER + ) breast cancer constitutes 70-75% of the disease incidence Tamoxifen has been the basis of endocrine therapy for patients with ER + breast cancer for more than three decades The treatment reduces the annual mortality rate of breast cancer by 31%, and remains the most effective targeted cancer therapy However, approximately one-third of patients treated with adjuvant tamoxifen suffer from aggressive recurrent disease Resistance to tamoxifen, thus, remains a major challenge in providing effective treatments for these patients In an effort to overcome the resistance, intensive research has been conducted to understand the underlying mechanisms; this has resulted in the identification of complex factors/pathways contributing to tamoxifen resistance, including modulations of the ERsignaling, upregulation of a set of growth factor receptor networks (HER2, EGFR, FGFR, and IGF1R), alterations of the PI3K-PTEN/AKT/mTOR pathway, and an elevation of the NF-κB signaling Despite these advances, our understanding of the acquired resistance remains fragmented and there is a lack of a platform to integrate these diversified molecular factors/ pathways into a cohesive mechanistic model Nonetheless, at the cellular level, it is becoming increasingly recongnized that cancer stem cells (CSCs) are key in driving cancer metastasis and therapy resistance Likewise, evidence is emerging for the critical contributions of breast cancer stem cells (BCSCs) to tamoxifen resistance In this review, we will discuss these recent developments of BCSC-mediated resistance to tamoxifen and the contributions of those demonstrated molecular factors/pathways to BCSC expansion during the emergency of tamoxifen resistance

Oxidative stress in COPD: molecular background and clinical monitoring.

Abstract: 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.

Structure Diversity, Synthesis, and Biological Activity of Cyathane Diterpenoids in Higher Fungi.

Abstract: Cyathane diterpenoids, occurring exclusively in higher basidiomycete (mushrooms), represent a structurally diverse class of natural products based on a characteristic 5-6-7 tricyclic carbon scaffold, including 105 members reported to date. These compounds show a diverse range of biological activities, such as antimicrobial, anti-MRSA, agonistic toward the kappa-opioid receptor, antiinflammatory, anti-proliferative and nerve growth factor (NGF)-like properties. The present review focuses on the structure diversity, structure elucidation and biological studies of these compounds, including mechanisms of actions and structure-activity relationships (SARs). In addition, new progress in chemical synthesis of cyathane diterpenoids is discussed.

Nucleic acid-based aptamers: applications, development and clinical trials.

Abstract: Short single-stranded oligonucleotides called aptamers, often termed as chemical antibodies, have been developed as powerful alternatives to traditional antibodies with respect to their obvious advantages like high specificity and affinity, longer shelf-life, easier manufacturing protocol, freedom to introduce chemical modifications for further improvement, etc. Reiterative selection process of aptamers over 10-15 cycles starting from a large initial pool of random nucleotide sequences renders them with high binding affinity, thereby making them extremely specific for their targets. Aptamer-based detection systems are well investigated and likely to displace primitive detection systems. Aptamer chimeras (combination of aptamers with another aptamer or biomacromolecule or chemical moiety) have the potential activity of both the parent molecules, and thus hold the capability to perform diverse functions at the same time. Owing to their extremely high specificity and lack of immunogenicity or pathogenicity, a number of other aptamers have recently entered clinical trials and have garnered favorable attention from pharmaceutical companies. Promising results from the clinical trials provide new hope to change the conventional style of therapy. Aptamers have attained high therapeutic relevance in a short time as compared to synthetic drugs and/or other modes of therapy. This review follows the various trends in aptamer technology including production, selection, modifications and success in clinical fields. It focusses largely on the various applications of aptamers which mainly depend upon their selection procedures. The review also sheds light on various modifications and chimerizations that have been implemented in order to improve the stability and functioning of the aptamers, including introduction of locked nucleic acids (LNAs). The application of various aptamers in detection systems has been discussed elaborately in order to stress on their role as efficient diagnostic agents. The key aspect of this review is focused on success of aptamers on the basis of their performance in clinical trials for various diseases.

Lipid nanocarriers (LNC) and their applications in ocular drug delivery.

Abstract: The peculiar physio-anatomical structure of the eye and the poor physico-chemical properties of many drug molecules are often responsible for the inefficient treatment of ocular diseases by conventional dosage forms, and justify the development of innovative ocular drug delivery systems. Lipid-based nanocarriers (LNC) are among the newer and interesting colloidal drug delivery systems; they show the capability to improve the local bioavailability of drugs administered by various ocular routes and, therefore, their therapeutic efficacy. Furthermore, their extreme biodegradability and biocompatible chemical nature have secured them the title of 'nanosafe carriers.' This review treats the main features of LNC [namely, solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) and lipid-drug conjugates (LDC)]; examples and advantages of the application of these colloidal carrier systems for the ophthalmic administration of drugs are presented.