Effects of ortho-eugenol on anxiety, working memory and oxidative stress in mice.

Ortho-eugenol is a synthetic derivative from eugenol, the major compound of clove essential oil, which has demonstrated antidepressant and antinociceptive effects in pioneering studies. Additionally, its effects appear to be dependent on the noradrenergic and dopaminergic systems. Depression and anxiety disorders are known to share a great overlap in their pathophysiology, and many drugs are effective in the treatment of both diseases. Furthermore, high levels of anxiety are related to working memory deficits and increased oxidative stress. Thus, in this study we investigated the effects of acute treatment of ortho-eugenol, at 50, 75 and 100 mg/kg, on anxiety, working memory and oxidative stress in male Swiss mice. Our results show that the 100 mg/kg dose increased the number of head-dips and reduced the latency in the hole-board test. The 50 mg/kg dose reduced malondialdehyde levels in the prefrontal cortex and the number of Y-maze entries compared to the MK-801-induced hyperlocomotion group. All doses reduced nitrite levels in the hippocampus. It was also possible to assess a statistical correlation between the reduction of oxidative stress and hyperlocomotion after the administration of ortho-eugenol. However, acute treatment was not able to prevent working memory deficits. Therefore, the present study shows that ortho-eugenol has an anxiolytic and antioxidant effect, and was able to prevent substance-induced hyperlocomotion. Our results contribute to the elucidation of the pharmacological profile of ortho-eugenol, as well as to direct further studies that seek to investigate its possible clinical applications.

Recent developments, characteristics and potential applications of screen-printed electrodes in pharmaceutical and biological analysis.

Screen-printed electrodes (SPEs) have gone through significant improvements over the past few decades with respect to both their format and their printing materials. Thus, SPEs have been successfully applied for the in situ detection of a plethora of analytes in a wide range of sample matrixes due to their advantageous material properties, such as disposability, simplicity, and rapid responses. In particular, the development of electrochemical sensors based on SPEs for pharmaceutical analysis has received massive consideration since they enable the rapid screening of the pharmaceutical compounds in complex matrixes, requiring small volumes of samples and no pre-treatment steps. This review summarizes the design and the working principles of electrochemical sensors based on SPEs applied to the quantification of pharmaceutical and biological compounds.

Changes in PLA(2) activity after interacting with anti-inflammatory drugs and model membranes: evidence for the involvement of tryptophan residues.

Phospholipase A(2) (PLA(2)) lipolytic activity can be regarded as a limiting factor for the development of inflammatory processes by restricting the production of pro-inflammatory mediators, hence representing a valuable therapeutic target for drugs that are able to modulate the activity of this enzyme. In the current work, the hydrolysis of phospholipids by PLA(2) was monitored with acrylodan-labelled intestinal fatty acid binding protein (ADIFAB) and this fluorescence based technique was also used to access the enzymatic inhibitory effect of non-steroidal anti-inflammatory drugs (NSAIDs). The intrinsic fluorescence of PLA(2) tryptophan residues was further used to gain complementary information regarding the accessibility of these residues on the PLA(2) structure upon interaction with the NSAIDs tested; and to calculate the NSAIDs-PLA(2) binding constants. Finally, circular dichroism (CD) measurements were performed to evaluate changes in PLA(2) conformation resultant from the inhibitory effect of the drugs tested. Overall, results gathered in this study point to the conclusion that the studied NSAIDs inhibit PLA(2) activity due to a disturbance of the enzyme binding efficiency to membrane interface possibly by a shielding effect of the Trp residues required for the membrane interfacial binding step that precedes lipolysis process.

A biophysical approach to phospholipase A2 activity and inhibition by anti-inflammatory drugs.

The present study describes the interaction of two nonsteroidal anti-inflammatory drugs (ibuprofen and piroxicam) with PLA(2) from Naja mossambica mossambica and seeks to deepen the knowledge about the influence of the biophysical properties of biomembranes, and the inhibitory effect of the drugs on the enzymatic activity. Fluorescent techniques with and without the use of probes, surface pressure/molecular area isotherms, surface pressure/time and molecular area/time measurements combined with circular dichroism spectroscopy and direct techniques of visualization of lipid membranes (Brewster angle microscopy), revealed that both drugs inhibit PLA(2). Additionally, the structure and characteristics of the lipid bilayer, as well as, the direct interaction of drugs with the enzyme seem to play an important role on the hydrolytic activity of PLA(2) towards membrane model systems. These results open a way of finding new and better strategies that can contribute to the development of suitable agents for relieving inflammatory conditions.

Effects of resveratrol on membrane biophysical properties: relevance for its pharmacological effects.

The current study gathers a range of spectrophotometric and spectrofluorimetric techniques to systematically monitor the effects of resveratrol (trans-3,5,4'-trihydrostilbene) on the biophysical properties of membrane model systems consisting of unilamellar liposomes of phosphatidylcholine (DPPC) with the ultimate goal of relating these effects with some of the well documented pharmacological properties of this compound, and clarifying some controversial results reported on the literature. Physiological conditions have been pursued, such as a buffered pH control with adjusted ionic strength similar to the blood plasma conditions (pH 7.4, I=0.1M) and the study at different membrane physical states (gel phase and fluid phase) for the assessment of resveratrol-membrane: aqueous partition coefficient by derivative spectroscopy. Results obtained by fluorescence quenching and anisotropy studies indicate that resveratrol has a membrane fluidizing effect and is able to permeate the membrane even in the gel phase. These results mirror the well described antioxidant effect of resveratrol, since antioxidants have to reach peroxidised rigid membranes and increase membrane fluidity in order to interact more efficiently with lipid radicals in the disordered lipid bilayer. Location of resveratrol pointed also to a membrane distribution that is favourable for scavenging the lipid radicals and was elucidated using probes positioned at different membrane depths suggesting that this compound penetrates into the acyl membrane region but also positions its polar hydroxyl group near the headgroup region of the membrane.

Drug-membrane interactions: significance for medicinal chemistry.

Generally drugs can act on the level of different biological membranes as well as inside the cells that are limited by membranes. Even in the latter situation, drugs must still interact with the membrane in order to cross it and reach their targets. For this reason, the efficiency of drugs to interact with the membranes constitutes one of the most important pharmacological features playing an essential role in their biological activity. Membranes are the gathering place of many proteins and lipids, and are the structures where most cellular activities occur. Although drugs bind to proteins and regulate their activity, the membrane lipid phase is no less important. Great part of compounds studied induces structural changes in the lipid phase resulting structural defects, which in turn disturb membrane function and indirectly modulate membrane proteins. This paper reviews the clinical significance of drug-membrane interaction studies with a special focus in the lipidic components of the membrane and reinforcing the importance of these studies in the field of medicinal chemistry since they constitute stimulating opportunities for understanding drugs mode of action and toxic effects and cannot be overlooked during drug design and synthesis.

Spectrophotometric determination of iron and boron in soil extracts using a multi-syringe flow injection system.

In the last decade, significant advances in flow analysis have been reported, namely the extensive use of computer-controlled devices to enhance the autonomy and performance of analysers. In the present work, computer-controlled multi-syringe flow injection systems are proposed to perform the spectrophotometric determination of available iron and boron in soil extracts. The methodologies were based on the formation of ferroin complex (determination of iron) and azomethine-H reaction (determination of boron). Both determinations were performed in manifolds with similar configurations by changing the reagents present in the different syringes. In the determination of iron, elimination of Schlieren effect in the detection system was achieved through the binary sampling approach, where a three-way valve was actuated to intercalate small slugs of sample and reagent, promoting better mixing conditions for solutions with different values of refractive index. In the determination of boron, in-line sample blank measurement was attained by omitting the introduction of reagent through software control, without manifold reconfiguration. Linear calibration curves were established between 0.50 and 10.0mgFel(-1) and between 0.20 and 4.0mgBl(-1). No systematic difference was found when soil extracts were analysed by the proposed methodologies and compared to the respective reference procedures.

Electrochemical and spectroscopic studies of the oxidation mechanism of the herbicide propanil.

Electrochemical oxidation of propanil in deuterated solutions was studied by cyclic, differential pulse, and square wave voltammetry using a glassy carbon microelectrode. The oxidation of propanil in deuterated acid solutions occurs at the nitrogen atom of the amide at a potential of +1.15 V vs Ag/AgCl. It was also found that, under the experimental conditions used, protonation at the oxygen atom of propanil occurs, leading to the appearance of another species in solution which oxidizes at +0.60 V. The anodic peak found at +0.79 V vs Ag/AgCl in deuterated basic solutions is related to the presence of an anionic species in which a negative charge is on the nitrogen atom. The electrochemical data were confirmed by the identification of all the species formed in acidic and basic deuterated solutions by means of NMR spectroscopy. The results are supported by electrochemical and spectroscopic studies of acetanilide in deuterated solutions.