Meloxicam and meloxicam-beta-cyclodextrin complex in model membranes: effects on the properties and enzymatic lipolysis of phospholipid monolayers in relation to anti-inflammatory activity

An eco-friendly fluorometric assay for high-sensitive meloxicam quantitation in biological matrices

Meloxicam (Mel), as a powerful and effective anti-inflammatory drug, is commonly employed for the treatment of various inflammatory diseases; however, the use of Mel at high doses or for extended periods could cause severe side effects in human visceral organs. Therefore, a simple, rapid, and reliable method is urgently needed to monitor Mel in biological samples. Herein, novel water-soluble luminescent nano-carbon dots (nano-Cdots) with outstanding physicochemical properties were prepared by a one-pot high-temperature hydrothermal process of ellagic acid and guanidine. The nano-Cdots were further used as an optical probe for the sensitive detection of Mel in serum samples through the cooperative mechanisms of the inner filter effect and photoelectron transfer. By employing this sensor, an excellent linear correlation was achieved between the relative luminescent intensity [(PL0 - PL)/PL0] and the concentration of Mel in the range of 0.1 to 200 μM, with a limit of detection of 34.68 nM (3σ/k). This sensor was effectively employed for the analysis of Mel in real serum samples, implying its potential development prospects for the advancement of drug analysis with carbon-based probes.

Nucleoside Analog Reverse-Transcriptase Inhibitors in Membrane Environment: Molecular Dynamics Simulations

The behavior of four drugs from the family of nucleoside analog reverse-transcriptase inhibitors (zalcitabine, stavudine, didanosine, and apricitabine) in a membrane environment was traced using molecular dynamics simulations. The simulation models included bilayers and monolayers composed of POPC and POPG phospholipids. It was demonstrated that the drugs have a higher affinity towards POPG membranes than POPC membranes due to attractive long-range electrostatic interactions. The results obtained for monolayers were consistent with those obtained for bilayers. The drugs accumulated in the phospholipid polar headgroup region. Two adsorption modes were distinguished. They differed in the degree of penetration of the hydrophilic headgroup region. Hydrogen bonds between drug molecules and phospholipid heads were responsible for adsorption. It was shown that apricitabine penetrated the hydrophilic part of the POPC and POPG membranes more effectively than the other drugs. Van der Waals interactions between S atoms and lipids were responsible for this.

Congo Red as a Supramolecular Carrier System for Doxorubicin: An Approach to Understanding the Mechanism of Action

The uptake and distribution of doxorubicin in the MCF7 line of breast-cancer cells were monitored by Raman measurements. It was demonstrated that bioavailability of doxorubicin can be significantly enhanced by applying Congo red. To understand the mechanism of doxorubicin delivery by Congo red supramolecular carriers, additional monolayer measurements and molecular dynamics simulations on model membranes were undertaken. Acting as molecular scissors, Congo red particles cut doxorubicin aggregates and incorporated them into small-sized Congo red clusters. The mixed doxorubicin/Congo red clusters were adsorbed to the hydrophilic part of the model membrane. Such behavior promoted transfer through the membrane.

A biocompatible high surface area ZnO-based molecularly imprinted polymer for the determination of meloxicam in water media and plasma

Ultrasound-assisted solid-phase microextraction (SPME) by a functionalized high surface area ZnO nanoparticle (NP)-based molecularly imprinted polymer (MIP) followed by UV-Vis spectrophotometry was described as a selective, economic and rapid technique which was established for the extraction and preconcentration of meloxicam (MEL) in water media and plasma.

Development and validation of ultra-performance liquid chromatography method for the determination of meloxicam and its impurities in active pharmaceutical ingredients

The main objective was to develop a suitable and rapid ultra-performance liquid chromatography (UPLC) method for the quantitative determination of meloxicam and its impurities. Starting from data in literature, we calculated the new parameters to translate a high performance liquid chromatography method used for the analysis of meloxicam with its major degradation products to UPLC method, and then we switched on many trials to optimize and improve its analytical performance. Chromatographic separation was achieved on ACQUITY UPLC HSS-T3 (2.1×100mm, 1.8μm). The eluted compounds were monitored at 260nm and 350nm. The flow rate was set at 0.4mL/min, injection volume at 0.8μl, and the column oven temperature was maintained at 45°C. The developed method was validated according to the International Conference on Harmonisation (ICH) guidelines for specificity, linearity, accuracy, precision, robustness, quantification limit, detection limit; and then applied to stability study of meloxicam subjected to different ICH prescribed stress conditions (hydrolysis, oxidation, heat and photolysis). The results show that the new UPLC method enables separation of meloxicam from its impurities in only 5min with a total mobile phase consumption of 1.8mL. All impurities get separated with good peak shapes and resolution factor greater than 2. The new method indicates stability and proved to be specific, precise accurate with linear correlation between concentrations and peak areas, allowing gain of more than six times analysis and more than twenty times solvent consumption, so in cost. Therefore, it can be beneficial for pharmaceutical industrial output.

Modulation of non steroidal anti-inflammatory drug induced membrane fusion by copper coordination of these drugs: anchoring effect

Membrane fusion, an integral event in several biological processes, is characterized by several intermediate steps guided by specific energy barriers. Hence, it requires the aid of fusogens to complete the process. Common fusogens, such as proteins/peptides, have the ability to overcome theses barriers by their conformational reorganization, an advantage not shared by small drug molecules. Hence, drug induced fusion at physiologically relevant drug concentrations is rare and occurs only in the case of the oxicam group of non steroidal anti-inflammatory drugs (NSAIDs). To use drugs to induce and control membrane fusion in various biochemical processes requires the understanding of how different parameters modulate fusion. Also, fusion efficacy needs to be enhanced. Here we have synthesized and used Cu(II) complexes of fusogenic oxicam NSAIDs, Meloxicam and Piroxicam, to induce fusion in model membranes monitored by using DSC, TEM, steady-state, and time-resolved spectroscopy. The ability of the complexes to anchor apposing model membranes to initiate/facilitate fusion has been demonstrated. This results in better fusion efficacy compared to the bare drugs. These complexes can take the fusion to its final step. Unlike other designed membrane anchors, the role of molecular recognition and strength of interaction between molecular partners is obliterated for these preformed Cu(II)-NSAIDs.

Vibrational spectroscopy for probing molecular-level interactions in organic films mimicking biointerfaces

Investigation into nanostructured organic films has served many purposes, including the design of functionalized surfaces that may be applied in biomedical devices and tissue engineering and for studying physiological processes depending on the interaction with cell membranes. Of particular relevance are Langmuir monolayers, Langmuir-Blodgett (LB) and layer-by-layer (LbL) films used to simulate biological interfaces. In this review, we shall focus on the use of vibrational spectroscopy methods to probe molecular-level interactions at biomimetic interfaces, with special emphasis on three surface-specific techniques, namely sum frequency generation (SFG), polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) and surface-enhanced Raman scattering (SERS). The two types of systems selected for exemplifying the potential of the methods are the cell membrane models and the functionalized surfaces with biomolecules. Examples will be given on how SFG and PM-IRRAS can be combined to determine the effects from biomolecules on cell membrane models, which include determination of the orientation and preservation of secondary structure. Crucial information for the action of biomolecules on model membranes has also been obtained with PM-IRRAS, as is the case of chitosan removing proteins from the membrane. SERS will be shown as promising for enabling detection limits down to the single-molecule level. The strengths and limitations of these methods will also be discussed, in addition to the prospects for the near future.

Interaction of nonsteroidal anti-inflammatory drugs with membranes: in vitro assessment and relevance for their biological actions

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly used drugs in the world due to their anti-inflammatory, analgesic and antipyretic properties. Nevertheless, the consumption of these drugs is still associated with the occurrence of a wide spectrum of adverse effects. Regarding the major role of membranes in cellular events, the hypothesis that the biological actions of NSAIDs may be related to their effect at the membrane level has triggered the in vitro assessment of NSAIDs-membrane interactions. The use of membrane mimetic models, cell cultures, a wide range of experimental techniques and molecular dynamics simulations has been providing significant information about drugs partition and location within membranes and also about their effect on diverse membrane properties. These studies have indeed been providing evidences that the effect of NSAIDs at membrane level may be an additional mechanism of action and toxicity of NSAIDs. In fact, the pharmacokinetic properties of NSAIDs are closely related to the ability of these drugs to interact and overcome biological membranes. Moreover, the therapeutic actions of NSAIDs may also result from the indirect inhibition of cyclooxygenase due to the disturbing effect of NSAIDs on membrane properties. Furthermore, increasing evidences suggest that the disordering effects of these drugs on membranes may be in the basis of the NSAIDs-induced toxicity in diverse organ systems. Overall, the study of NSAIDs-membrane interactions has proved to be not only important for the better understanding of their pharmacological actions, but also for the rational development of new approaches to overcome NSAIDs adverse effects.

Differentiating oxicam nonsteroidal anti-inflammatory drugs in phosphoglyceride monolayers

Meloxicam, piroxicam, and tenoxicam belong to a highly potent oxicam group of nonsteroidal anti-inflammatory drugs. Whereas the structurally similar oxicams have different pharmacokinetics, treatment efficiency, and adverse effects, their common mechanism of action is the inhibition of a membrane enzyme, cyclooxygenase. Because the prerequisite for accessing the cyclooxygenase by the drugs is interaction with the membrane, the focus of the current study was a comparison of how meloxicam, piroxicam, and tenoxicam interact with lipid monolayers used as models of biological membranes. The monolayers were formed with 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol), 1,2-dipalmitoyl-sn-glycero-3-phospho-l-serine, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, 1,2-myristoyl-sn-glycero-3-phosphoethanolamine, and 1,2-dilauroyl-sn-glycero-3-phosphoethanolamine. These systems were examined via surface pressure and surface electrical potential measurements, polarization modulation infrared reflection adsorption spectra, and Brewster angle microscopy. The three oxicams are differentiated in the monolayers; meloxicam shows the highest ability to modify membrane fluidity and surface potential, followed by piroxicam and tenoxicam. The dissimilarity of the biological activity of the oxicams may be linked to different interaction with the membrane, as revealed by the present study.