Current Medicinal Chemistry (v.16, #12)

Screening for Liver Disease - are LFTs Old HAT? by Robert Lo, Kara Rye, Andrew Austin, Jan Freeman (1442-1450).
The economic burden of end stage liver disease is set to increase due to the rising prevalence of cirrhosis secondary to alcohol, viral hepatitis and fatty liver disease. Screening for liver disease has been advocated, as most cases of cirrhosis are preventable with early interventions. Liver function tests (LFTs) are routinely used as a first line investigation to screen for liver diseases but can be normal despite significant underlying liver fibrosis, hepatitis, steatohepatitis or even cirrhosis. Their relationships are far from linear and with little predictive value in some cases. Newer non-invasive modalities are emerging but currently their roles are largely experimental. This review will discuss the role of serum biomarkers and imaging techniques as new modalities to screen for liver disease.

Chemoprotective Mechanism of the Natural Compounds, Epigallocatechin- 3-O-Gallate, Quercetin and Curcumin Against Cancer and Cardiovascular Diseases by Smita Jagtap, Kesavan Meganathan, Vilas Wagh, Johannes Winkler, Jurgen Hescheler, Agapios Sachinidis (1451-1462).
Cancer and cardiovascular disease (CVD) chemoprevention can be achieved by the use of natural, synthetic, or biologic compounds to reverse, suppress, or prevent the development of diseases. Chemoprevention is a potential anticancer approach, which has reduced secondary effects in comparison to classical prophylaxis. Natural compounds such as flavonoids reduce oxidative stress, which is the most likely mechanism in the protective effects of these compounds. Even though the exact mechanisms of action are not well understood another central action mechanism of polyphenolic flavonoids seems to be an induction of apoptosis as demonstrated in numerous cellular systems. Moreover, flavonoids may modulate protein and lipid kinase signaling pathways. Understanding the mechanism of these natural products will contribute to the development of more specific preventive strategies against cancer and CVD. Much of the research in the field is focused on epigallocatechin-3-O-gallate (EGCG), quercetin and curcumin, which were found to have beneficial effects against cancer and CVD. We review the chemoprotective mechanisms through which these natural compounds exert their beneficial effects against cancer and CVDs.

Antipsychotic and Antiepileptic Drugs in Bipolar Disorder: The Importance of Therapeutic Drug Monitoring by Alessandro Musenga, Maria Saracino, Gabriele Sani, Maria Raggi (1463-1481).
Bipolar disorder (BD) is a long-term illness with mood swings which are characterized by recurrent episodes of mania/hypomania and depression, with variable interpolations of relatively asymptomatic periods, called euthymic, in which, however, some psychopathological symptoms may persist. Although mood stabilizers, such as lithium, are the first-line treatment for the prevention of new BD episodes, combination therapy has become the standard of care for BD patients. Besides lithium, the use of a mood stabilizer along with an atypical antipsychotic is recommended in many patients. Recently, atypical antipsychotics (quetiapine, olanzapine, risperidone and aripiprazole) and antiepileptic agents (valproate, lamotrigine and oxcarbazepine) are increasingly used as mood stabilizers. To reduce side effects and optimize treatment it is important to perform accurate monitoring of drug blood levels in these patients, who are often treated with multiple drugs. Therapeutic drug monitoring (TDM) is in fact a powerful tool that, starting from clinical-chemical correlation data, allows to tailor-cut treatment to the specific needs of individual patients; hence the need to have reliable analytical methods available for the determination of plasma levels of drugs and their metabolites. Analyses of biological samples are mainly carried out using high-performance liquid chromatography (HPLC) coupled with different detectors, capillary electrophoresis and gas-chromatography. Various procedures are employed to remove biological interferences before analyzing the samples. This review focuses on currently available analytical TDM methods for atypical antipsychotics and antiepileptic agents used in the treatment of patients with bipolar disorder. Advantages and limitations of the various analytical methods will be reviewed and discussed, together with an evaluation of the role of TDM.

In systemic lupus erythematosus (SLE), the interaction between hyperactive T cells and B cells causes a dysregulated production of autoantibodies that can lead to tissue damage and impaired organ function. Studies on the modalities of communication between T and B cells have led to the design of new therapeutics for SLE, including autoantibodyderived peptide immunotherapies. Since many autoantibodies in SLE patients have amino acid sequences similar to those of murine antibodies, and at similar locations, the current directions are to employ strategies that have given promising results in mice in human clinical settings. This review describes the experimental evidence, rationale, and preclinical models of autoantibody-derived peptide immunotherapy in SLE, and how this information is translating into clinical studies in humans.

Toxic, Immunostimulatory and Antagonist Gluten Peptides in Celiac Disease by Marco Silano, Olimpia Vincentini, Massimo De Vincenzi (1489-1498).
Celiac disease (CD) is an increasingly diagnosed, permanent autoimmune enteropathy, triggered, in susceptible individuals, by the ingestion of gluten, the alcohol – soluble protein fraction of some cereals, such as wheat, rye and barley. The main protein of wheat gluten is called gliadin, the similar proteins of rye and barley are secalin and hordein, respectively. Approximately 96and#x25; of CD patients express the HLA molecule DQ2, while the remainder mostly express the less common haplotype DQ8, reflecting the pivotal role of these molecules in the pathogenesis of CD. Because of their aminoacid sequence and tri-dimensional structure, gluten peptides selectively bind to these HLA alleles present on the surface of antigen presenting cells and then they are presented to the T lymphocytes in intestinal mucosa, thus starting the inflammatory immune response. CD is defined by the characteristic histological changes of small bowel mucosa: villous atrophy, crypts hyperplasia and T cells infiltration of the lamina propria, along with the increase of the number of intraepithelial lymphocytes. The withdrawal of the gluten- containing food from the diet determines a complete recovery of the intestinal mucosa, whereas the reintroduction causes a relapse of the disease. This review focuses on the description of gluten peptides that elicit the mucosal immune response via the activation of innate and adaptive immunity in CD. It also describes the antagonist gluten peptides, obtained by artificial modification of gluten T epitopes or naturally occurring in the alcohol protein fraction of a cultivar of durum wheat, able to immunomodulate the pathogenic immune response of CD.

Pre-Clinical and Clinical Evaluation of Nuclear Tracers for the Molecular Imaging of Vulnerable Atherosclerosis: An Overview by L. Riou, A. Broisat, J. Dimastromatteo, G. Pons, D. Fagret, C. Ghezzi (1499-1511).
Cardiovascular diseases (CVD) are the leading cause of mortality worldwide. Despite major advances in the treatment of CVD, a high proportion of CVD victims die suddenly while being apparently healthy, the great majority of these accidents being due to the rupture or erosion of a vulnerable coronary atherosclerotic plaque. A non-invasive imaging methodology allowing the early detection of vulnerable atherosclerotic plaques in selected individuals prior to the occurrence of any symptom would therefore be of great public health benefit. Nuclear imaging could allow the identification of vulnerable patients by non-invasive in vivo scintigraphic imaging following administration of a radiolabeled tracer. The purpose of this review is to provide an overview of radiotracers that have been recently evaluated for the detection of vulnerable plaques together with the biological rationale that initiated their development. Radiotracers targeted at the inflammatory process seem particularly relevant and promising. Recently, macrophage targeting allowed the experimental in vivo detection of atherosclerosis using either SPECT or PET. A few tracers have also been evaluated clinically. Targeting of apoptosis and macrophage metabolism both allowed the imaging of vulnerable plaques in carotid vessels of patients. However, nuclear imaging of vulnerable plaques at the level of coronary arteries remains challenging, mostly because of their small size and their vicinity with unbound circulating tracer. The experimental and pilot clinical studies reviewed in the present paper represent a fundamental step prior to the evaluation of the efficacy of any selected tracer for the early, non-invasive detection of vulnerable patients.

Novel Approaches to Control Biofilm Infections by Andreia Estrela, Marcela Heck, Wolf-Rainer Abraham (1512-1530).
Biofilms are matrix-enclosed microbial aggregations that adhere to biological or non-biological surfaces. They represent a significant and incompletely understood mode of growth for bacteria and fungi. Biofilm infections cause many deaths and high health costs worldwide. Biofilm infections on indwelling devices or implants are difficult to eradicate because of their much better protection against macrophages and antibiotics, compared to free living cells, leading to severe clinical complications often with lethal outcome. One promising approach to combat biofilm infections independent from the conventional control by antibiotics is the generation of functional surfaces preventing the attachment of bacteria. Another aim is the communication machinery used by bacteria to establish a biofilm, the so called quorum-sensing. Here, small diffusible compounds are produced and sensed by the producing cells to measure their concentration and hence cell density. Natural compounds and synthetic analogues have been used successfully to prevent biofilm formation by quorum- quenching. These compounds are still in the preclinical phase, often struggling with toxicity. A principal problem of quorum-quenchers is their high species specificity, resulting in the control of only some pathogenic strains leaving other pathogens untouched. A field still in its infancy is the control of virulence factors expression not preventing the biofilm but suppressing its virulence. This review will give an overview over the pros and cons of the individual targets and an outlook of future developments.

Medicinal Treatments of Cholesterol Gallstones: Old, Current and New Perspectives by P. Portincasa, Agostino Di Ciaula, Helen Wang, Antonio Moschetta, David Wang (1531-1542).
Cholesterol cholelithiasis is one of the most common and costly digestive diseases. Although gallstones are usually asymptomatic and no treatment is generally required, it is imperative to treat symptomatic gallstones with or without complicated conditions. Laparoscopic cholecystectomy is first-line therapy for symptomatic gallstones. By contrast, a cautious study on the natural history of the disease and costs of therapy, indicates that non-surgical treatment of gallstones is currently restricted to a subgroup of patients with mild symptoms or with small radiolucent cholesterol gallstones in a functioning gallbladder. Appropriate selection of patients suitable for medical therapy is therefore of key importance. Oral litholysis with the hydrophilic bile acid ursodeoxycholic acid induces cholesterol desaturation of bile and may lead to gallstone dissolution in patients with small, radiolucent, cholesterol-enriched stones in a functioning gallbladder with a patent cystic duct. Recent studies from experimental animal models and preliminary findings in humans also suggest that blocking intestinal absorption of cholesterol with the powerful, specific, and effective NPC1L1 inhibitor ezetimibe, may offer a novel and exciting strategy for the treatment of cholesterol gallstones. A similar possibility might arise from manipulation of specific nuclear receptors involved in cholesterol and bile acid homeostasis. Current views and perspectives on medicinal treatment of cholesterol gallstone disease are discussed here.

Antioxidants in Wild Mushrooms by Isabel Ferreira, Lillian Barros, Rui Abreu (1543-1560).
Maintenance of equilibrium between free radical production and antioxidant defences (enzymatic and non enzymatic) is an essential condition for normal organism functioning. When this equilibrium has a tendency for the production of free radicals we say that the organism is in oxidative stress. In this situation, excess free radicals may damage cellular lipids, proteins and DNA, affecting normal function and leading to various diseases. In aerobic organisms, the free radicals are constantly produced during the normal cellular metabolism, mainly in the form of Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS). Exposition of the organism to free radicals has led to the development of endogenous defence mechanisms to eliminate them. These defences were the response of evolution to the inevitability of ROS production in aerobic conditions. Natural products with antioxidant activity may help the endogenous defence system. In this perspective the antioxidants present in the diet assume a major importance as possible protector agents reducing oxidative damage. Particularly, the antioxidant properties of wild mushrooms have been extensively studied by our research group and by others, and many antioxidant compounds extracted from these sources have been identified, such as phenolic compounds, tocopherols, ascorbic acid, and carotenoids. We will review the compounds identified so far in mushrooms, as well as the mechanism of action involved in their antioxidant properties. Wild mushrooms might be used directly in diet and promote health, taking advantage of the additive and synergistic effects of all the bioactive compounds present.