Current Pharmaceutical Analysis - Volume 3, Issue 1, 2007

The tumor necrosis factor-α (TNF-α) system is involved in several regulatory processes within the body. The action of TNF-α is mediated by the two cell surface receptors TNF-R p55 and TNF-R p75. Soluble TNF receptors (sTNFRs) are soluble variants of the extracellular domains of their membrane-bound form. To assess the activity of the TNF-α system in patients suffering from disorders of the central nervous system - such as depression, narcolepsy, multiple sclerosis, Alzheimer’s and Parkinson’s disease - and during psychopharmacological therapy, several studies investigated plasma levels of TNF-α, TNF-R p55 and TNF-R p75 and the local concentration of TNF-α in the brain. It could be shown that an activation of the TNF-α system might promote the development of psychiatric or neurological symptoms or disorders. Additionally, endocrine changes associated with brain disorders may lead to alterations of the TNF-α system. Psychotropic drugs influence the TNF-α system by normalizing the HPA axis changes associated with psychiatric diseases, and inducing weight gain and liver damage. Several side effects of psychotropic drugs resemble brain disorders in which the TNF-α system plays an important pathogenetic role. One could wonder whether these side effects may at least in part be mediated by an activation of the TNF-α system.

Inflammation is a key element in the pathophysiology of Central Nervous System (CNS) diseases, irrespective of the etiology of such diseases. From inflammatory or infectious diseases to neurodegenerative, ischemic or traumatic diseases, inflammation plays a fundamental role both in controlling the ongoing pathological processes and in promoting neuroprotection or regeneration. Indeed, due to the complex architecture and activities in the brain, the side effects of brain inflammation are fundamental to the outcome of neurological diseases (for example bystander neuronal damage). The CNS differs from the other organs as it is partially isolated from the immune system by the restrictive blood-brain barrier and the presence of an immunosuppressive environment (brain immune privilege). Inappropriate immune responses are responsible for diseases such as Multiple Sclerosis (MS) or for the increased disability after brain trauma or stroke. Inflammation also plays an important role in neurodegenerative diseases such as Alzheimer (AD) or Parkinson diseases (PD). However, in certain circumstances immune responses in the brain might have a neuroprotective effect, possibly mediating the release of trophic factors by inflammatory or glial cells. Neurotrophic factors protect axons and myelin from inflammatory damage, and they have immunosuppressive properties that contribute to the maintenance of brain immune privilege. Thus, in addition to their neuroprotective activities, neurotrophic factors may offer new therapeutic perspectives by targeting inflammatory processes in brain disorders.

Lipid disorders are common in diabetes mellitus (DM), and play crucial roles in the development of diabetic cardiovascular complications. Diabetic dyslipidemia is characterized by hypertriglyceridemia, increased levels of very low density lipoproteins (VLDL), small dense low density lipoprotein (LDL), and decreased levels of high density lipoprotein (HDL)-cholesterol. The activity of lipoprotein lipase is reduced in diabetic patients, which attenuates the lipolysis of triglyceride-rich lipoproteins and the uptake of free fatty acids. The increased uptake of triglycerides in liver promotes the production of VLDL. Hypertriglyceridemia promotes the exchange of cholesteryl ester from HDL to VLDL or LDL for triglycerides. Obesity or nephropathy deteriorates the dyslipidemia in DM patients. The initial management of lipid disorders in diabetic patients without cardiovascular disease is lifestyle intervention and glucose control. The abnormalities in the metabolism of LDL or HDL in diabetic patients often require pharmacological intervention. Target of LDL-cholesterol (LDL-c) is more restrict in diabetic patients than in non-diabetic subjects. Treatment with HMG-CoA reductase inhibitors (statins) effectively reduces LDL-c and cardiac events, and that was associated with moderately increases in HDL-c. The combination of ezetimibe with a statin helps to achieve LDL-c target in patients with unsatisfactory cholesterol lowering by statin alone. Fibrates (PPAR-α agonists) or PPAR-γ agonists reduce the levels of triglycerides and moderately elevate HDL-c. PPAR-γ agonists also improve insulin sensitivity. Cholesteryl ester transfer protein inhibitors may dramatically increase HDL-c. Lipid management has been considered as an effective approach to reduce cardiovascular risk in diabetes.

Endogenous estrogens, namely estradiol, estriol and estrone are essential substances for the sexual determination, growth and reproduction of human beings. Their levels in the human sera are important index in monitoring pregnancy, evaluating menstrual dysfunctions and diagnosing many other diseases. On the other hand, many exoestrogens, including the phytoestrogen such as isoflavones, the synthetic estrogens such as diethylstilbestrol and chemicals of industry origin with suspected estrogenic activity such as bisphenol A and 4-nonylphenol, are drawing increasing attention in recent years. This paper reviews the main immunochemical analytical methods for these important estrogenic substances. The immunizing hapten design and its influence on the specificity of produced antibody were discussed. The typical available immunoassays including enzyme immunoassay (EIA), fluoroimmunoassay (FIA) and chemiluminescence immunoassay (CLIA) for the detection of estrogens were compared with respect to their features (especially dynamic range and limit of detection). The performance of different types of immunosensors with respect to their advantages and disadvantages were evaluated. The future developing trend in this field was also briefly discussed.

Free radical-induced peroxidation of arachidonic acid and other polyunsaturated fatty acids esterified to lipids and subsequent hydrolysis generates prostaglandin-like compounds including the isoprostanes and neuroprostanes. These compounds are endogenously formed, characteristic in structure, stable, and accessible to quantitative determination in tissue, plasma and urine. Isoprostanes have emerged as reliable markers of lipid peroxidation in vivo in humans. Among them 8-iso-prostaglandin (PG) F2α (8-iso-PGF2α, 8-epi-PGF2α, 15-F2t-IsoP, iPF2α-III) and its major urinary metabolites, i.e. 2,3-dinor-4,5-dihydro-8-iso-PGF2α and 2,3-dinor-8-iso-PGF2α, are subject of extensive investigation. Different analytical approaches are currently used to isolate, identify and quantify various members of the isoprostane and neuroprostane families. They include chromatographic approaches such as thin-layer chromatography (TLC), highperformance liquid chromatography (HPLC), and gas chromatography (GC), and in particular mass spectrometry (MS)- based techniques. Gas chromatography-mass spectrometry (i.e. GC-MS and GC-tandem MS), previously proved as the most reliable quantitative technique in the field of prostanoid research, was the first method which was applied to measure isoprostanes. In recent years, liquid chromatography-tandem mass spectrometry (i.e. LC-tandem MS) has also been introduced and established in the analysis of isoprostanes and related compounds. The present paper gives an overview of analytical methods currently applied to analyze isoprostanes in various biological matrices. Special emphasis is given to the quantitative determination in human urine which is a non-invasive method. In this context, the impact of solid-phase extraction (SPE), immunoaffinity column chromatography (IAC), HPLC, and TLC in sample preparation/purification is discussed. Differences in sample preparation depending on the biological matrix, i.e. tissue, blood plasma, and urine, are outlined. Furthermore, to meet increasing interest in isoprostanes as valid and stable markers of oxidative stress in human disease, results from various clinical trials in the cardiovascular field are discussed and relevant experimental findings as well as potential direct effects of isoprostanes in these pathophysiological settings are reviewed. Moreover, relevant clinical data from other disease entities is summarized in a schematic fashion.

Many of the new chemical entities under development in the pharmaceutical industry are chiral. The specific stereochemistry of these substances affects both the biological activity and commercial viability of the potential new drug. Thus, enantioselective separation techniques play a vital role in the development of these entities into commercial products. In an attempt to improve upon the efficiency of chiral method development, column manufacturers and industry scientists have developed screening procedures to efficiently evaluate various chiral separation conditions in an unattended mode. While these systems have been shown to be successful in their initial and literature studies, it is important to evaluate these systems for the molecules of interest to each particular business concern. After optimizing the analysis conditions of several literature chiral screening procedures, the individual screens were challenged by novel chemical entities developed for commercial use. The entities were randomly selected based on availability and how well they represent molecules of interest to common pharmaceutical portfolios. Our chiral screening program is currently focusing on four separation technologies: a) Liquid Chromatography (LC), b) Supercritical Fluid Chromatography (SFC), c) Capillary Electrophoresis (CE), and Gas Chromatography (GC). An overview of the results from each of these screens, future directions and a final unified strategy for chiral method development screening are presented.

With the advancement of science and technology chiral chromatography has achieved an important place in analytical science. Coated polysaccharide chiral stationary phases (CSPs) are most popular due to their high chiral recognition power. But during last few years, immobilization of polysaccharide derivatives with silica gel has opened new realms in this area as these CSPs can be used with normal and prohibited solvents (tetrahydrofuran, chloroform, dichloromethane, acetone, 1,4-dioxane, ethylacetate, and certain other ethers). The present article describes status and method protocol of immobilized polysaccharides CSPs for the chiral resolution of different racemates using liquid chromatography. The contents of this article include methods of immobilization, their applications under optimized conditions, enantioselectivities, efficiencies and a comparison of the chiral recognition capabilities of coated vs immobilized CSPs.