Photolytic degradation of ibuprofen. Toxicity of the isolated photoproducts on fibroblasts and erythrocytes

Spectroscopic Analysis of the Effect of Ibuprofen Degradation Products on the Interaction between Ibuprofen and Human Serum Albumin

BACKGROUND

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are one of the most commonly used groups of medicinal compounds in the world. The wide access to NSAIDs and the various ways of storing them due to their easy accessibility often entail the problem with the stability and durability resulting from the exposure of drugs to external factors. The aim of the research was to evaluate in vitro the mechanism of competition between ibuprofen (IBU) and its degradation products, i.e., 4'-isobutylacetophenone (IBAP) and (2RS)-2-(4- formylphenyl)propionic acid (FPPA) during transport in a complex with fatted (HSA) and defatted (dHSA) human serum albumin.

METHODS

The research was carried out using spectroscopic techniques, such as spectrophotometry, infrared spectroscopy and nuclear magnetic resonance spectroscopy.

RESULTS

The comprehensive application of spectroscopic techniques allowed, among others, for the determination of the binding constant, the number of classes of binding sites and the cooperativeness constant of the analyzed systems IBU-(d)HSA, IBU-(d)HSA-FPPA, IBU-(d)HSA-IBAP; the determination of the effect of ibuprofen and its degradation products on the secondary structure of albumin; identification and assessment of interactions between ligand and albumin; assessment of the impact of the presence of fatty acids in the structure of albumin and the measurement temperature on the binding of IBU, IBAP and FPPA to (d)HSA.

CONCLUSION

The conducted research allowed us to conclude that the presence of ibuprofen degradation products and the increase in their concentration significantly affect the formation of the IBU-albumin complex and thus, the value of the association constant of the drug, changing the concentration of its free fraction in the blood plasma. It was also found that the presence of an ibuprofen degradation product in a complex with albumin affects its secondary structure.

Photodegradation and ozonation of ibuprofen derivatives in the water environment: Kinetics approach and assessment of mineralization and biodegradability

This article presents the results of studies on the degradation of ibuprofen transformation products: 1-hydroxyibuprofen (1OHIBF), 4-ethylbenzaldehyde (4EBA), 1-[4-(2-methylpropyl)phenyl]ethan-1-ol (MPPE) in water. To the best of our knowledge, this is the first paper where the ozonation and photodegradation (VIS and UV photolysis, degradation in H₂O₂/UV system, photosensitized oxidation) of 1OHIBF, 4EBA and MPPE are reported. The processes were performed in demineralized and natural river water. The influence of various reaction parameters on the removal degree was checked. Both, photolysis under VIS light and photosensitized oxidation of target compounds are very low-efficient processes. Ozonation and degradation in H₂O₂/UV system are effective methods for ibuprofen derivatives degradation. Components present in river water reduced removal degree of investigated compounds during ozonation and degradation in H₂O₂/UV system. The biodegradability assessment using the Average Oxidation State (AOS) and COD/TOC ratio proved the formation of more oxidized by-products during both processes. The determined second-order rate constants for ozone reaction with 1OHIBF, 4EBA and MPPE are 0.1 ± 0.01, 10.95 ± 1.36 and 3.04 ± 0.33 M^-1 s^-1, respectively. The calculated reaction rate constants of hydroxyl radicals with MPPE, 4EBA and 1OHIBF are 3.57 × 10⁹, 6.83 × 10⁹ and 1.06 × 10⁹ M^-1 s^-1, respectively.

Solar photocatalytic degradation of ibuprofen with a magnetic catalyst: Effects of parameters, efficiency in effluent, mechanism and toxicity evolution

The environmental-friendly photocatalytic process with a magnetic catalyst CoFe₂O₄/TiO₂ mediated by solar light for ibuprofen (IBP) degradation in pure water, wastewater effluent and artificial seawater was investigated systematically. The study aims to reveal the efficiency, the mechanism and toxicity evolution during IBP degradation. Hydroxyl radicals and photo-hole (h⁺) were found to contribute to the IBP decay. The presence of SO₄^2- showed no significant effect, while NO₃^- accelerated the photodegradation, and other anions including HCO₃^-, Cl^-, F^-, and Br^- showed significant inhibition. The removal efficiency was significantly elevated with the addition of peroxymonosulfate (PMS) or persulfate (PS) ([Oxidant]₀:[IBP]₀ = 0.4-4), with reaction rate of 5.3-13.1 and 1.3-2.9 times as high as the control group, respectively. However, the reaction was slowed down with the introduction of H₂O₂. A mathematic model was employed to describe the effect of ferrate, high concentration or stepwise addition of ferrate was suggested to play a positive role in IBP photodegradation. Thirteen transformation products were identified and five of them were newly reported. The degradation pathways including hydroxylation, the benzene ring opening and the oxidation of carbon were proposed. IBP can be efficiently removed when spiked in wastewater and seawater despite the decreased degradation rate by 41% and 56%, respectively. Compared to the IBP removal, mineralization was relatively lower. The adverse effect of the parent compound IBP to the green algae Chlorella vulgaris was gradually eliminated with the decomposition of IBP. The transformation product C178a which possibly posed toxicity to rotifers Brachionus calyciflorus can also be efficiently removed, indicating that the photocatalysis process is effective in IBP removal, mineralization and toxicity elimination.

Ozonation catalysed by ferrosilicon for the degradation of ibuprofen in water

The search for optimal catalysts to improve the working efficiency of ozonation has always been an important issue in the research field of advanced oxidation processes. In this study, a novel catalyst, ferrosilicon, was selected as the catalyst in heterogeneous catalytic ozonation to degrade ibuprofen (IBP) in water and treat real pharmaceutical wastewater. During the procedure, 45^#ferrosilicon exhibited the best catalytic activity. Under the optimized experimental conditions, the IBP removal reached 75%, which was a great improvement compared to the 37% removal by ozone alone. The 45^#-ferrosilicon-catalysed ozonation also achieved 68% TOC removal for real pharmaceutical wastewater, which was 31% higher than that by ozone alone. The degradation pathway of IBP was proposed using GC/MS. The EPR test proved that the main active species in the system were free active radicals •OH, and the measured accumulative •OH amount was 102 μmol. The characterization results show that the nascent metallic oxides, hydroxides, and hydroxyoxides on the ferrosilicon surface facilitated the decomposition of ozone molecules and generation of free active radicals. The removal of target organic contaminants in the water was mainly attributed to the oxidization of these highly active species.

Monitoring Commercial Ibuprofen Potency Changes Over 1 Year When Stored in a Household Setting

Background: Most over-the-counter medications are labeled for storage in a dry, room temperature environment. Despite this, many households store medications in the bathroom, where temperature and humidity extremes may be experienced. Objective: In this project, we sought to investigate the effect that long-term storage in a household bathroom had on potency of over-the-counter ibuprofen (IBU) products as well as on the emergence of a known toxic degradation product, 4-isobutylacetophenone (4-IBP). Methods: A liquid chromatography-tandem mass spectrometry method was developed for the quantitative determination of IBU and 4-IBP in aqueous samples. Three brands each of IBU tablets (200 mg) and suspensions (100 mg/5 mL) were assayed for IBU concentration at the initiation of the study and once monthly thereafter. The samples were stored in a household bathroom, with continuous temperature and humidity monitoring. Each sample was assayed in triplicate and percent recovery was calculated against freshly prepared standards of IBU using bulk powder. Results: Tablets maintained >90% average strength through 3 months, with statistically significant deviation from initial concentration (2-way analysis of variance, P = .05) detected after 6 to 7 months. Suspensions maintained >90% average strength through 5 months, with statistically significant changes from initial concentration emerging after 7 months. After 12 months, the average strength was 73% and 83% for tablets and suspensions, respectively. 4-IBP was not detected in any of the samples during the duration of the study. Conclusions: These data indicate that, while 4-IBP was not detected following 12-month bathroom storage of commercial IBU products, significant changes in potency should negatively affect efficacy.

Micro-TiO2 coated glass surfaces safely abate drugs in surface water

The ingredients of Pharmaceuticals and Personal Care Products (PPCPs) persist in water and conventional treatment plants are not able to remove them efficiently. Sonochemical treatment is insufficient to mineralize organics such as ibuprofen into CO₂ and H₂O. TiO₂ degrades ibuprofen (IBP) under UV light; however, it does not reach a high grade of conversion. Here, we investigated the mineralization of ibuprofen to CO₂ by TiO₂ UV-C photocatalysis. We replaced nano-sized P25 (the standard catalyst) with a micro-sized commercial sample of TiO₂ to preclude the use of nanoparticles which are dangerous for human health and because typical filtration systems are expensive and inefficient. We deposited micro-TiO₂ on glass Raschig rings to ensure an easy recovery and reuse of the photocatalyst and we studied its performance both with a batch and a continuous reactor. Micro-TiO₂ mineralized 100% of IBP in 24 h. TiO₂-coated glass Raschig rings degraded 87% of IBP in 6 h of UV-C irradiation in a continuous reactor, with a mineralization of 25%. Electronspray ionization mass spectrometer (ESI-MS, positive mode) analyses identified 13 different byproducts and we hypothised a degradration pathway for IBP degradation.

Adsorption and photocatalytic removal of Ibuprofen by activated carbon impregnated with TiO2 by UV-Vis monitoring

The removal of Ibuprofen was investigated by activated carbon impregnated with TiO₂. Emphasis was given on the effect of different parameters, such as composite type, initial Ibuprofen concentration (5-25 mg/L), temperature (22-28 °C) and pH (acidic and alkaline solution). The experiment was carried out in a self-made tubular flow reactor, with one 15 W monochromatic UV lamp (254 nm). The composite AC90T10 gives the highest removal degree of 92% of Ibuprofen solution under UV light within 4 h, due to synergy of adsorption and photodegradation. It was found that weight ratio of composite/Ibuprofen has limited effect on the removal degree within the concentration range (5-25 mg/L), but reaction time under UV light (4 h) and pH (acidic solution) are very important. The kinetic experimental data obtained at pH 4.3 at 25 °C on different composites were fitted to pseudo-first, pseudo-second and Elovich models, obtaining a high accuracy based on R² values. From the results, composites of granular activated carbon and TiO₂ can enhance removal of Ibuprofen effectively, making recycle process much easier and less costly, which can be a promising method in future water treatment.

Application of BiOX Photocatalysts in Remediation of Persistent Organic Pollutants

Bismuth oxyhalides have recently gained attention for their promise as photocatalysts. Due to their layered structure, these materials present fascinating and highly desirable physicochemical properties including visible light photocatalytic capability and improved charge separation. While bismuth oxyhalides have been rigorously evaluated for the photocatalytic degradation of dyes and many synthesis strategies have been employed to enhance this property, relatively little work has been done to test them against pharmaceuticals and pesticides. These persistent organic pollutants are identified as emerging concerns by the EPA and effective strategies must be developed to combat them. Here, we review recent work directed at characterizing the nature of the interactions between bismuth oxyhalides and persistent organic pollutants using techniques including LC-MS/MS for the determination of photocatalytic degradation intermediates and radical scavenging to determine active species during photocatalytic degradation. The reported investigations indicate that the high activity of bismuth oxyhalides for the breakdown of persistent organic pollutants from water can be largely attributed to the strong oxidizing power of electron holes in the valence band. Unlike conventional catalysts like TiO2, these catalysts can also function in ambient solar conditions. This suggests a much wider potential use for these materials as green catalysts for industrial photocatalytic transformation, particularly in flow chemistry applications.

Photocatalytic degradation of ibuprofen over BiOCl nanosheets with identification of intermediates

Photocatalysis directed at the removal of persistent organic pollutants, including pharmaceuticals, has been the subject of intense recent research. Bismuth oxychloride (BiOCl) has emerged as a potential alternative to traditional photocatalysts and has shown competitive removal efficiencies. However, pathways responsible for BiOCl photodegradation have not been well characterized. The present work is the first to determine, using LC-MS/MS analysis, the pathways by which BiOCl removes ibuprofen (IBP) from water. HPLC-DAD and LC-MS/MS analyses show that BiOCl converts IBP to two primary photochemical products, 4-isobutylacetophenone (IBAP) and 1-(4-isobutylphenyl)ethanol (IBPE). The reactivity for BiOCl is attributed to interactions of the carboxylic acid group of IBP with holes in the valence band. Hydroxylated-IBP was not detected in BiOCl photocatalytic degradation experiments which would be expected in a process driven by the formation and reactivity of reactive oxygen species. These data were used to formulate a photocatalytic degradation pathway for IBP and highlight the importance of studying both primary and secondary degradation reactions for photocatalytic studies.

Enhanced electrochemical degradation of ibuprofen in aqueous solution by PtRu alloy catalyst

Electrochemical advanced oxidation processes (EAOPs) regarded as a green technology for aqueous ibuprofen treatment was investigated in this study. Multi-walled carbon nanotubes (MWCNTs), Pt nanoparticles (Pt NPs), and PtRu alloy, of which physicochemical properties were characterized by XRD and X-ray absorption spectroscopy, were used to synthesize three types of cheap and effective anodes based on commercial conductive glass. Furthermore, the operating parameters, such as the current densities, initial concentrations, and solution pH were also investigated. The intermediates determined by a UPLC-Q-TOF/MS system were used to evaluate the possible reaction pathway of ibuprofen (IBU). The results revealed that the usage of MWCNTs and PtRu alloy can effectively reduce the grain size of electrocatalysts and increase the surface activity from the XRD and XANES analysis. The results of CV analysis, degradation and mineralization efficiencies revealed that the EAOPs with PtRu-FTO anode were very effective due to advantages of the higher capacitance, CO tolerance, catalytic ability at less positive voltage and stability. The concentration trend of intermediates indicated that the potential cytotoxic to human caused by 1-(1-hydroxyenthyl)-4-isobutylbenzene was completely eliminated as the reaction time reaches 60 min. Therefore, EAOPs combined with synthesized anodes can be feasibly applied on the electrochemical degradation of ibuprofen.

Ibuprofen photodegradation in aqueous solutions

The advanced treatment of polluted liquid streams containing traces of pharmaceutical compounds is a major issue, since more and more effluents from pharma labs and wastewaters containing the excretions of medically treated humans and animals are discharged in the conventional wastewater treatment plants without previous effective treatments. Ibuprofen is a widely used non-steroidal anti-inflammatory drug (NSAID), which explains why it is found in wastewaters so often. In this paper, the removal of IBP from simulated water streams was investigated by using a lab-scale experimental device, consisting of a batch reactor equipped with a lamp emitting monochromatic UV light at a fixed wavelength (254 nm) and various intensities. Three sets of experiments were carried out: the first to study IBP concentration as a function of time, at different volumes of treated solutions (V = 10-30 mL); the second to explore the effect of pH on IBP degradation as a function of time (pH = 2.25-8.25) and the third to evaluate the effect of different UV light intensities on IBP degradation (E = 100-400 mJ m^-2). The IBP initial concentration (IBP ₀) was varied in the range 30-60 mg L^-1. The results obtained show that the concentration of IBP decreases along with treatment time, with a negative effect of the treated volume, i.e. smaller volumes, such as lower liquid heights, are more easily degraded. Moreover, the higher the pH, the better the IBP degradation; actually, when pH increases from 2.25 to 6.6 and 8.25, the IBP concentration, after an hour of treatment, decreases respectively to 45, 34 and 27 % of its initial value. In addition, as the intensity of light increases from 100 to 400 mJ m^-2, the IBP concentration decreases to 34 % of its initial value. A reaction scheme is put forward in the paper, which well describes the effects of volume, pH and light intensity on the IBP degradation measured experimentally. Moreover, the IBP degradation by-products have been identified.

Photodegradation of ibuprofen under UV-Vis irradiation: mechanism and toxicity of photolysis products

The photodegradation of ibuprofen (IBP) in aqueous media was studied in this paper. The degradation mechanism, the reaction kinetics and toxicity of the photolysis products of IBP under UV-Vis irradiation were investigated by dissolved oxygen experiments, quenching experiments of reactive oxygen species (ROS), and toxicity evaluation utilizing Vibrio fischeri. The results demonstrated that the IBP degradation process could be fitted by the pseudo first-order kinetics model. The degradation of IBP by UV-Vis irradiation included direct photolysis and self-sensitization via ROS. The presence of dissolved oxygen inhibited the photodegradation of IBP, which indicated that direct photolysis was more rapid than the self-sensitization. The contribution rates of ·OH and (1)O2 were 21.8 % and 38.6 % in self-sensitization, respectively. Ibuprofen generated a number of intermediate products that were more toxic than the base compound during photodegradation.

Photogenerated α,n-didehydrotoluenes from chlorophenylacetic acids at physiological pH

Aromatic diradicals are recognized as promising intermediates for DNA cleavage, but their formation has thus far been limited to the Bergman and Myers–Saito cycloaromatizations. We report here the phototriggered generation of all isomers of the potential DNA-cleaving α,n-didehydrotoluene diradicals at physiological pH, accomplished by the irradiation of chlorophenylacetic acids under mild conditions. The desired diradicals were formed upon photolysis of the chosen aromatic in aqueous phosphate buffer solution (pH = 7.3), with the consecutive elimination of biologically compatible chloride ion and carbon dioxide. Theoretical simulations reveal that the efficient decarboxylation of the primarily generated phenyl cations involves a previously not known diradical structure.

A quantitative toxicogenomics assay reveals the evolution and nature of toxicity during the transformation of environmental pollutants

The incomplete mineralization of contaminants of emerging concern (CECs) during the advanced oxidation processes can generate transformation products that exhibit toxicity comparable to or greater than that of the original contaminant. In this study, we demonstrated the application of a novel, fast, and cost-effective quantitative toxicogenomics-based approach for the evaluation of the evolution and nature of toxicity along the electro-Fenton oxidative degradation of three representative CECs whose oxidative degradation pathways have been relatively well studied, bisphenol A, triclosan, and ibuprofen. The evolution of toxicity as a result of the transformation of parent chemicals and production of intermediates during the course of degradation are monitored, and the quantitative toxicogenomics assay results revealed the dynamic toxicity changes and mechanisms, as well as their association with identified intermediates during the electro-Fenton oxidation process of the selected CECs. Although for the three CECs, a majority (>75%) of the parent compounds disappeared at the 15 min reaction time, the nearly complete elimination of toxicity required a minimal 30 min reaction time, and they seem to correspond to the disappearance of identified aromatic intermediates. Bisphenol A led to a wide range of stress responses, and some identified transformation products containing phenolic or quinone group, such as 1,4-benzoquinone and hydroquinone, likely contributed to the transit toxicity exhibited as DNA stress (genotoxicity) and membrane stress during the degradation. Triclosan is known to cause severe oxidative stress, and although the oxidative damage potential decreased concomitantly with the disappearance of triclosan after a 15 min reaction, the sustained toxicity associated with both membrane and protein stress was likely attributed at least partially to the production of 2,4-dichlorophenol that is known to cause the production of abnormal proteins and affect the cell membrane. Ibuprofen affects the cell transporter function and exhibited significantly high membrane stress related to both membrane structure and function. Oxidative degradation of ibuprofen led to a shift in its toxicity profile from mainly membrane stress to one that exhibited not only sustained membrane stress but also protein stress and DNA stress. The information-rich and high-resolution toxicogenomics results served as "fingerprints" that discerned and revealed the toxicity mechanism at the molecular level among the CECs and their oxidation transformation products. This study demonstrated that the quantitative toxicogenomics assay can serve as a useful tool for remediation technology efficacy assessment and provide guidance about process design and optimization for desired toxicity elimination and risk reduction.

Photochemical transformation of ibuprofen into harmful 4-isobutylacetophenone: pathways, kinetics, and significance for surface waters

The harmful compound 4-isobutylacetophenone (IBAP) can be formed photochemically from the anti-inflammatory drug ibuprofen (IBP), upon direct photolysis (yield 25 ± 7%, μ ± σ), reaction with ·OH (yield 2.3 ± 0.1%) and reaction with triplet states of chromophoric dissolved organic matter, (3)CDOM* (yield 31 ± 4%). In the latter case, anthraquinone-2-sulphonate was used as CDOM proxy. The three processes would account for most of the photochemical transformation of IBP and IBAP in surface waters. IBAP formation from IBP involves the propanoic acid chain, which is more reactive than the aromatic ring as shown by quantum mechanical calculations. IBAP is expected to undergo slightly faster photochemical transformation than IBP in surface waters, with a modelled pseudo-first order rate constant that is higher by 1.5-1.9 times compared to IBP. Due to fairly high formation yields and depending on IBP emission scenarios, photochemical modelling suggests that IBAP could reach concentration values up to ~15% of IBP in surface waters, thus being a potentially important transformation intermediate. This issue prompts for the need of field studies that provide information on IBAP environmental occurrence, which is virtually unknown at the present moment.

Hydroxyl radical induced degradation of ibuprofen

Pulse radiolysis experiments were used to characterize the intermediates formed from ibuprofen during electron beam irradiation in a solution of 0.1mmoldm(-3). For end product characterization (60)Co γ-irradiation was used and the samples were evaluated either by taking their UV-vis spectra or by HPLC with UV or MS detection. The reactions of OH resulted in hydroxycyclohexadienyl type radical intermediates. The intermediates produced in further reactions hydroxylated the derivatives of ibuprofen as final products. The hydrated electron attacked the carboxyl group. Ibuprofen degradation is more efficient under oxidative conditions than under reductive conditions. The ecotoxicity of the solution was monitored by Daphnia magna standard microbiotest and Vibrio fischeri luminescent bacteria test. The toxic effect of the aerated ibuprofen solution first increased upon irradiation indicating a higher toxicity of the first degradation products, then decreased with increasing absorbed dose.

Fulvic acid mediated photolysis of ibuprofen in water

Photolysis of the non-steroidal anti-inflammatory drug ibuprofen was studied by exposure to a solar simulator in solutions of fulvic acid (FA) isolated from Pony Lake, Antarctica; Suwannee River, GA, USA; and Old Woman Creek, OH, USA. At an initial concentration of 10 μM, ibuprofen degrades by direct photolysis, but the presence of FA significantly increases reaction rates. These reactions proceeded up to 6× faster in FA solutions at lower ibuprofen concentrations (0.1 μM), but the rates are highly dependent upon DOM composition. Incomplete quenching of the reaction in the presence of isopropanol suggests that the hydroxyl radical is only partially responsible for ibuprofen's photodegradation in FA solutions, and other reactive transients likely play an important role. Liquid chromatography-quadrupole time-of-flight mass spectrometry and NMR spectroscopy reveal the formation of multiple photoproducts, with three byproducts identified as 1-(4-isobutylphenyl)ethanol, isobutylacetophenone, and a phenol derivative. Pony Lake FA significantly increases the production of the major byproduct relative to yields produced by direct photolysis and the other two FA. Thus, the photolytic fate of ibuprofen in sunlit waters is affected by its initial concentration and the source of dissolved organic matter present.

Photodegradation of fleroxacin injection: different products with different concentration levels

Photodegradation of fleroxacin is investigated in different injections and solutions. After UV irradiation, fleroxacin was degraded to afford two major products in large-volume injection (specification, 200 mg:100 ml), while degraded to afford another major product in small-volume injection (specification, 200 mg:2 ml). The photodegradation products were detected and isolated by reversed-phase HPLC. Based on the spectral data (FT-IR, MS(n), TOF-MS, (1)H/(13)C, DEPT, and 2D NMR), the structures of these products were: 8-fluoro-9-(4-methyl-piperazin-1-yl)-6-oxo-2,3-dihydro-6H-1-oxa-3a-aza-phenalene-5-carboxylic acid (impurity-I); 6-fluoro-1-(2-fluoro-ethyl)-7-(2-methylamino-ethylamino)-4-oxo-1,4-dihydro-quinoline-3-carboxylic acid (impurity-II); and 6,8-difluoro-1-(2-fluoro-ethyl)-7-(2-methylamino-ethylamino)-4-oxo-1,4-dihydro-quinoline-3-carboxylic acid (impurity-III), respectively. Different photodegradation pathways of fleroxacin were proposed, which led to the different stability characteristics of fleroxacin in the injections. The fluorine atom at C8 is more photolabile in dilute injection, so defluorination and cyclization reactions are prone to take place, whereas photo irradiation only cause ring-opening oxidation reaction of piperazine side chain in concentrated injection.

Microbial transformation of Ibuprofen by a nocardia species

The carboxylic acid functional group of ibuprofen [alpha-methyl-4-(2-methylpropyl) benzene acetic acid] is reduced to the corresponding alcohol and subsequently esterified to the acetate derivative by cultures of Nocardia species strain NRRL 5646. The alcohol and ester microbial transformation products were isolated, and their structures were determined by H and C nuclear magnetic resonance spectroscopy and mass spectrometry. By derivatization of synthetic and microbiologically produced ibuprofen alcohols with S(+)-O-acetylmandelic acid, nuclear magnetic resonance analysis indicated that the carboxylic acid reductase of Nocardia sp. is R enantioselective, giving alcohol products with an enantiomeric excess of 61.2%. The R enantioselectivity of the carboxylic acid reductase enzyme system was confirmed by using cell extracts together with ATP and NADPH in the reduction of isomeric ibuprofens.

Ability of white-rot fungi to remove selected pharmaceuticals and identification of degradation products of ibuprofen by Trametes versicolor

A screening using four white-rot fungi (Trametes versicolor, Irpex lacteus, Ganoderma lucidum and Phanerochaete chrysosporium) was performed on the degradation of 10 mg L(-1) of ibuprofen (IBU, anti-inflammatory), clofibric acid (CLOFI, lipid regulator) and carbamazepine (CARBA, antiepileptic/analgetic) after 7 d of incubation. Whereas IBU was extensively degraded by all the fungi tested, T. versicolor was the only strain able to degrade either CLOFI (approximately 91%) and CARBA (approximately 58%), although the latter was also degraded by G. lucidum (approximately 47%). In vitro experiments using manganese peroxidase and laccase-mediator system showed that extracellular fungal enzyme systems did not appear to play a role in the first step of degradation. However, our in vivo studies using the cytochrome P450 inhibitors 1-aminobenzotriazole and piperonyl butoxide suggested that the cytochrome P450 system may be involved in the first step of CLOFI and CARBA oxidation by T. versicolor. During the very early stages of IBU degradation by T. versicolor, two hydroxylated metabolites were detected: 1-hydroxy ibuprofen and 2-hydroxy ibuprofen. These byproducts were subsequently degraded by the fungus to 1,2-dihydroxy ibuprofen, that was not reported in biological systems to date. Furthermore, these results are of particular interest because CLOFI and CARBA are highly persistent in the aquatic environment and they pass unchanged or poorly transformed in wastewater treatment plants.

A novel hollow-fibre microporous membrane liquid–liquid extraction for determination of free 4-isobutylacetophenone concentration at ultra trace level in environmental aqueous samples

In this study, a method was developed for determination of the free concentration of 4-isobutylacetophenone, a toxic degradation product of ibuprofen, in river and sewage water samples from Sweden. Sample preparation and analysis were performed by a hollow-fibre microporous membrane liquid-liquid extraction (HF-MMLLE) set-up and gas chromatography-mass spectrometry (GC-MS), respectively. In this novel approach, only the liquid in the membrane pores is utilised for non-depleting extraction. Several parameters were studied, including: type of organic solvent, sample pH, and salt and humic acid content. The optimised method allowed the determination of the analyte at the ng L(-1) level in river and sewage water. A linear plot gave a correlation coefficient better than 0.992 and resulted in a limit of detection of 7 and 14 ng L(-1) for river and sewage water, respectively. The enrichment factor was over 2000 in the fibre and over 300 after dilution. The repeatability and reproducibility were better than 5% and 10%, respectively. For the first time, 4-isobutylacetophenone was found at free concentrations of 40 ng L(-1) or below in sewage waters, while it could not be quantified in a river downstream from a municipal sewage treatment plant.

Pain and quality of life for patients with venous leg ulcers: proof of concept of the efficacy of Biatain®-Ibu, a new pain reducing wound dressing

Wound pain is a serious problem for elderly patients suffering from chronic leg ulcers, and it may lead to reduced wound healing rates and reduced quality of life. Biatain-Ibu Non-adhesive (Coloplast A/S), a new pain-reducing moist wound healing dressing containing ibuprofen was tested for pain reduction, safety, and efficacy on 10+2 patients in a single-blinded crossover study against Biatain Non-adhesive (Coloplast A/S). Pain was measured with a Numeric Box Scale before, during, and after dressing change. Quality of life was measured using the World Health Organization-5 Well-Being Index. Dressing moist wound healing properties such as absorption capacity and leakage were tested together with assessment of wound exudate and blood plasma content of ibuprofen. Use of the Biatain-Ibu foam dressing correlated with a decrease in pain intensity scores from 7 in the run-in period to approximately 2.5 in the Biatain-Ibu treatment phase. Quality of life measures were improved which together with the reduced pain could contribute to faster wound healing. The moist wound healing properties of Biatain-Ibu were similar to that of the Biatain Non-adhesive and ulcer size was reduced by 24% during the treatment period. Neither side effects nor systemic plasma concentrations of ibuprofen were observed. These data indicate that Biatain-Ibu could reduce persistent and temporary wound pain, increase Quality of life, was found safe to use, and had excellent moist wound healing properties.

Comparison of different ibuprofen-amino acid compounds with respect to emulsifying and cytotoxic properties

Sodium ibuprofen (Ibu-Na) and different ibuprofen-amino acid compounds, lysinate (Ibu-Lys), arginate (Ibu-Arg) and histidinate (Ibu-His), were evaluated for emulsifying, haemolytic and cytotoxic properties. The highest reduction of surface tension was obtained with Ibu-Lys which shows good emulsifying qualities. At the same time, Ibu-Lys reveals the highest haemolytic activity and affects porcine cornea integrity. However, incorporation of Ibu-Lys into an emulsion system significantly decreases haemolysis. On the contrary Ibu-Arg, which shows a lower surface tension reduction, allows, unlike Ibu-Na and Ibu-His, for comparably stable emulsions with comparable erythrocyte damage.

Identification of degradation products of ibuprofen arising from oxidative and thermal treatments

Ibuprofen is a widely utilised analgesic anti-inflammatory drug. It is sensitive to oxidation and photodegradation. In this work, the oxidative and thermal degradations were investigated. The treatments adopted allowed the detection of 13 degradation products, seven of which have never been reported: hydratropic acid, 4-ethylbenzaldehyde, 4-(1-carboxyethyl)benzoic acid, 1-(4-isobutylphenyl)-1-ethanol, 2-[4-(1-hydroxy-2-methylpropyl)phenyl]propanoic acid, 1-isobutyl-4-vinylbenzene, 4-isobutylphenol. For 1-(4-isobutylphenyl)-1-ethanol, the in vitro toxic effects have already been described in the literature. To detect all degradation products, two RP-HPLC methods and a GC-MS procedure were developed or modified from the official monographs. The identification was conducted by evaluating chromatographic and spectral data and the structural attributions were confirmed by simple and univocal synthesis. Moreover, the actual presence of these molecules in marketed medicinal products was investigated.

Drug-induced cutaneous photosensitivity: incidence, mechanism, prevention and management

The interaction of sunlight with drug medication leads to photosensitivity responses in susceptible patients, and has the potential to increase the incidence of skin cancer. Adverse photosensitivity responses to drugs occur predominantly as a phototoxic reaction which is more immediate than photoallergy, and can be reversed by withdrawal or substitution of the drug. The bias and inaccuracy of the reporting procedure for these adverse reactions is a consequence of the difficulty in distinguishing between sunburn and a mild drug photosensitivity reaction, together with the patient being able to control the incidence by taking protective action. The drug classes that currently are eliciting a high level of adverse photosensitivity are the diuretic, antibacterial and nonsteroidal anti-inflammatory drugs (NSAIDs). Photosensitising chemicals usually have a low molecular weight (200 to 500 Daltons) and are planar, tricyclic, or polycyclic configurations, often with heteroatoms in their structures enabling resonance stabilisation. All absorb ultraviolet (UV) and/or visible radiation, a characteristic that is essential for the chemical to be regarded as a photosensitiser. The photochemical and photobiological mechanisms underlying the adverse reactions caused by the more photoactive drugs are mainly free radical in nature, but reactive oxygen species are also involved. Drugs that contain chlorine substituents in their chemical structure, such as hydrochlorthiazide, furosemide and chlorpromazine, exhibit photochemical activity that is traced to the UV-induced dissociation of the chlorine substituent leading to free radical reactions with lipids, proteins and DNA. The photochemical mechanisms for the NSAIDs that contain the 2-aryl propionic acid group involve decarboxylation as the primary step, with subsequent free radical activity. In aerated systems, the reactive excited singlet form of oxygen is produced with high efficiency. This form of oxygen is highly reactive towards lipids and proteins. NSAIDs without the 2-arylpropionic acid group are also photoactive, but with differing mechanisms leading to a less severe biological outcome. In the antibacterial drug class, the tetracyclines, fluoroquinolones and sulfonamides are the most photoactive. Photocontact dermatitis due to topically applied agents interacting with sunlight has been reported for some sunscreen and cosmetic ingredients, as well as local anaesthetic and anti-acne agents. Prevention of photosensitivity involves adequate protection from the sun with clothing and sunscreens. In concert with the preponderance of free radical mechanisms involving the photosensitising drugs, some recent studies suggest that diet supplementation with antioxidants may be beneficial in increasing the minimum erythemal UV radiation dose.

Cell damage induced by Angiovist-370 and 308nm excimer laser radiation

BACKGROUND AND OBJECTIVE

Radiographic contrast media containing iodine-labeled organic compounds can be present in the irradiated field during laser angioplasty using 308 nm excimer laser radiation. These compounds absorb light at 308 nm and may undergo photochemical reactions that produce products that damage cells.

STUDY DESIGN/MATERIALS AND METHODS

This study was undertaken to determine whether photoproducts that damage human lymphocytes in vitro are formed when Angiovist 370 (AV), a contrast medium containing triiodinated aromatic compounds, is exposed to 308 nm radiation.

RESULTS

The absorption spectrum of AV developed a new peak at 360 nm that extended to wavelengths greater than 500 nm when dilute AV solutions were exposed to 308 nm radiation indicating that photoproducts were formed. Irradiating dilute AV solutions above a layer of human lymphocytes caused a dose-dependent decrease in thymidine incorporation using fluence rates between 5.2 x 10(6) and 1.0 x 10(8) W/cm2. Decreased DNA synthesis was independent of the pulse length (10 ns vs. 230 ns) but was lower, at a given dose, when the highest fluence rate was used. Incubation of lymphocytes with preirradiated AV solutions also decreased incorporation of thymidine in a radiation dose-dependent manner. The cell damaging photoproducts in preirradiated AV solutions were unstable; within 15 min, the effectiveness had decreased by approximately 85%.

CONCLUSIONS

These results indicate that exposure of AV to 308 nm excimer laser radiation produces photochemical products that damage human cells in vitro.

Photodegradation and phototoxicity studies of furosemide. Involvement of singlet oxygen in the photoinduced hemolysis and lipid peroxidation

The phototoxic diuretic drug furosemide (1), a 5-(aminosulfonyl)-4-chloro-2-[(2-furanylmethyl)-amino] benzoic acid is photolabile under aerobic and anaerobic conditions. Irradiation of a methanol solution of 1 under oxygen produces photoproducts 2, 3, 4 and singlet oxygen, while under argon the photoproducts 2 and 4 were isolated. A peroxidic unstable photoproduct was detected during the photolysis under oxygen atmosphere. The formation of singlet oxygen by photolysis of 1 was evidenced by trapping with 2,5-dimethylfuran (GC-mass), furfuryl alcohol and 1,3-cyclohexadiene-1,4-diethanoate (HPLC) as 1O2 scavengers and by the histidine test. Furosemide was screened in vitro at different concentrations for UV-Vis-induced phototoxic effects in a photohemolysis test, in the presence and absence of different radical scavengers, singlet oxygen and hydroxyl radical quenchers. However, furosemide photosensitized the peroxidation of linoleic acid, as monitored by the UV-detection of dienic hydroperoxides and it also photosensitized the oxidation of histidine. The photodegradation was catalyzed in the presence of human serum albumin. Studies on peripheral blood mononuclear and polymorphonuclear cells (lymphocytes and neutrophils) demonstrated no phototoxicity on these cell lines.

Molecular mechanism of drug photosensitization. Part 6. Photohaemolysis sensitized by tolmetin

The photosensitizing properties of tolmetin, 5-(p-toluoyl)-1-methyl-2-pyrrolyacetic acid (TLM), have been studied in vitro following the lysis of erythrocytes in phosphate buffer suspensions irradiated with UVA light in the presence of the drug. It was found that the phototoxic properties of the drug are negligible in nitrogen and significant in aerated medium, but that they decrease in oxygen-saturated solution. The investigation of the drug photolysis showed that TLM undergoes photodecarboxylation to p-tolyl 1,2-dimethyl-5-pyrrolyl ketone in nitrogen and to p-tolyl 1-methyl-2-hydroxymethyl-5-pyrrolyl ketone and 5-(p-toluoyl)-1-methyl-2-pyrrole carbaldehyde in air. These photoproducts also undergo photodegradation. The comparison between the photohaemolysis and photolysis results and the effect of suitable additives such as sodium azide, mannitol, butylated hydroxy-anisole, reduced glutathione, superoxide dismutase and copper (II) suggest that the phototoxicity of TLM can be attributed essentially to singlet oxygen in the first step and to its photoproducts when they accumulate and compete with the starting drug in light absorption. Their phototoxic effect is much higher with respect to that of TLM, as shown by comparison of the doses needed to attain 50% photohaemolysis.

Molecular mechanism of drug photosensitization. 7. Photocleavage of DNA sensitized by suprofen

Ultraviolet-A irradiation of a suprofen (2-[4-2(2-thenoyl) phenyl]propionic acid) (SPF) buffered solution (pH 7.4) in the presence of supercoiled pBR322 DNA leads to single strand breaks with the formation of an open circular form and subsequent linearization of the plasmid. On the basis of agarose gel electrophoresis data of samples irradiated in an air-saturated solution or in an oxygen-modified atmosphere, and the effects of sodium azide, D20, mannitol, copper(II), superoxide dismutase, 2-H-propanol, deferoxamine and surfactants, we suggest a photosensitization mechanism involving singlet oxygen and free radicals. The higher rate of photocleavage in nitrogen compared to that in an air-saturated solution and the results obtained from oxygen consumption measurements support the hypothesis that both the type I and type II photosensitization mechanisms are operative and that oxygen quenches the excited state of the irradiated drug. The photosensitization model applied was in agreement with that previously applied to cell membrane SPF photoinduced damage. Interaction of the drug with DNA, studied through circular dichroism and fluorescence anisotropy, probably occurs through a surface binding mode. The experimental techniques used for assessing the photodamaging activity of this drug may be useful for screening of phototoxic compounds in the environment and for determining the active species involved.

Photodegradation of some quinolones used as antimicrobial therapeutics

The photostability of the fluoroquinolones ciprofloxacin (CPX), ofloxacin (OFX), and fleroxacin (FLX) toward ultraviolet irradiation (UVA) and room light was investigated in dilute aqueous solutions. A series of photoproducts was observed by high-performance liquid chromatography (HPLC) for all three drugs. As little as 1 h of exposure to room light was enough for the formation of detectable amounts of CPX photoproducts. The major CPX photoproduct was characterized as a dimer by liquid secondary ion mass spectrometry, but its structure was not determined. Since irradiation of CPX results (as cited in ref/11) in a loss of antibacterial activity and since all substances, parent drugs as well as their photoproducts, are potential candidates for undesired drug effects, quinolone drugs should be strictly protected from all light during storage and administration.

Photodynamic lipid peroxidation by the photosensitizing nonsteroidal antiinflammatory drugs suprofen and tiaprofenic acid

The photochemistry of the photosensitizing nonsteroidal antiinflammatory drugs tiaprofenic acid and suprofen involves the intermediacy of short-lived species (i.e. radicals). The data obtained in the present work strongly suggest that such intermediates may be responsible for the phototoxicity of 2-arylpropionic acids by inducing photodynamic lipid peroxidation at drug concentrations likely to be reached in the skin. This has been investigated using linoleic acid as a model lipid and determining the amount of hydroperoxides by measuring the spectrophotometric absorption at 233 nm, associated with the formation of dienic hydroperoxides. The major photoproducts of tiaprofenic acid and suprofen are derivatives bearing an ethyl side chain. Photoproducts of this type, due to the lack of polar moieties, are highly lipophilic and likely to accumulate in the lipid bilayer of cell membranes. Taking into account their ability to induce photodynamic lipid peroxidation and their marked photostability, it is conceivable that such photoproducts can participate in many catalytic cycles, playing a significant role in the mechanism of photosensitization by tiaprofenic acid and suprofen.

Oxidative decarboxylation of naproxen

The decarboxylation of naproxen (1H) and its salt (1-) was achieved by means of chemical [Ce(IV) or S2O8(2-)] and electrochemical oxidation. The product patterns were compatible with mechanisms involving single-electron transfer from the pi-system or the carboxylate moiety. The results are discussed in connection with the involvement of electron-transfer processes in the reported phototoxicity of naproxen.

Phototoxicity of non-steroidal anti-inflammatory drugs: in vitro testing of the photoproducts of Butibufen and Flurbiprofen

In this work, the phototoxicity of two non-steroidal anti-inflammatory drugs, Butibufen and Flurbiprofen, was examined. Both were unstable to light, to give several photoproducts which were isolated and identified. The different photoproducts were formed by a primary photochemical mechanism which involves an initial cleavage of the C-C bond alpha to the carbonyl group, followed by several secondary processes. The cytotoxic effects of the xenobiotics were evaluated using two well-established biological in vitro tests: (a) enzyme leakage lactate dehydrogenase and glutamate-oxaloacetate transaminase from cultured fibroblasts and (b) lysis of red blood cells. The benzylic alcohols caused extensive leakage from cultured fibroblasts at the different concentrations assayed. The alcohol obtained from Butibufen was a potent lytic agent for human red blood cells. The other photoproducts, Butibufen and Flurbiprofen did not produce observable toxic effects on cells.

Photochemistry of tiaprofenic acid, a nonsteroidal anti-inflammatory drug with phototoxic side effects

The phototoxic nonsteroidal anti-inflammatory drug tiaprofenic acid (1) is photolabile under aerobic conditions. Irradiation of a methanol solution of 1 under oxygen produces the photoproducts 2, 3, 4, and 5, and also produces a singlet oxygen as evidenced by trapping with 2,5-dimethylfuran.