Metabolomic Fingerprint Assay in Zebrafish Embryos

In order for new drugs to enter the market, extensive studies are needed to examine toxic effects. Among others, teratogenicity studies are of paramount importance. Of even higher importance is to gain knowledge on the biological responses that take place upon drug exposure, so as to have a better understanding of the molecular mechanisms that govern developmental changes. Metabolomics is the research field that studies the changes in the chemical composition of metabolites contained within cells. Conducting metabolomics studies results in valuable information. Zebrafish is a vertebrate model organism that bridges in vivo assays and in vivo studies. In this chapter, we propose a metabolomic fingerprint assay for the study of metabolic changes in zebrafish embryos upon exposure to various drugs. The metabolome of zebrafish is extracted, and the 1H-NMR spectrum is recorded. Using open-access metabolomic databases, a list of tentative metabolites is retrieved. The presence of the tentative metabolites is further confirmed by UHPLC-HRMS. Ultimately, after a metabolic pathway analysis, the metabolic network is revealed and useful conclusions can be drawn.

Two-Birds-with-One-Stone Synthesis of Hydrophilic and Hydrophobic Fluorescent Carbon Nanodots from Dunaliella salina Biomass as 4-Nitrophenol Nanoprobes Based on Inner Filter Effect and First Derivative Redshift of Emission Band

4-Nitrophenol (4-NP) has been listed as a priority pollutant and has also been reported as a human urinary metabolite used as a marker to evaluate exposure to certain pesticides. In the work herein, a solvothermal approach is applied to the one-pot synthesis of both hydrophilic and hydrophobic fluorescent carbon nanodots (CNDs), utilizing the halophilic microalgae Dunaliella salina as a biomass precursor. Both kinds of the produced CNDs showed appreciable optical properties and quantum yields, good photostability and they were capable of probing 4-NP by quenching their fluorescence through the inner filter effect. Interestingly, a prominent 4-NP concentration-dependent redshift of the corresponding emission band of the hydrophilic CNDs was noticed, which was further exploited, for the first time, as an analytical platform. Capitalizing on these properties, analytical methods were developed and applied to a variety of matrixes, such as tap water, treated municipal wastewater and human urine. The method based on the hydrophilic CNDs (λ_ex/λ_em: 330/420 nm) was linear in the range of 0.80-45.0 μM and showed acceptable recoveries (from 102.2 to 113.7%) with relative standard deviations of 2.1% (intra-day) and 2.8% (inter-day) for the quenching-based detection mode and 2.9% (intra-day) and 3.5% (inter-day) for the redshift one. The method based on the hydrophobic CNDs (λ_ex/λ_em: 380/465 nm) was linear in the range of 1.4-23.0 μM, with recoveries laying within the range of 98.2-104.5% and relative standard deviations of 3.3% and 4.0% for intra-day and inter-day assays, respectively.

Untargeted metabolomics of human keratinocytes reveals the impact of exposure to 2,6-dichloro-1,4-benzoquinone and 2,6-dichloro-3-hydroxy-1,4-benzoquinone as emerging disinfection by-products

INTRODUCTION

The 2,6-dichloro-1,4-benzoquinone (DCBQ) and its derivative 2,6-dichloro-3-hydroxy-1,4-benzoquinone (DCBQ-OH) are disinfection by-products (DBPs) and emerging pollutants in the environment. They are considered to be of particular importance as they have a high potential of toxicity and they are likely to be carcinogenic.

OBJECTIVES

In this study, human epidermal keratinocyte cells (HaCaT) were exposed to the DCBQ and its derivative DCBQ-OH, at concentrations equivalent to their IC₂₀ and IC₅₀, and a study of the metabolic phenotype of cells was performed.

METHODS

The perturbations induced in cellular metabolites and their relative content were screened and evaluated through a metabolomic study, using 1H-NMR and MS spectroscopy.

RESULTS

Changes in the metabolic pathways of HaCaT at concentrations corresponding to IC₂₀ and IC₅₀ of DCBQ-OH involved the activation of cell membrane α-linolenic acid, biotin, and glutathione and deactivation of glycolysis/gluconeogenesis at IC₅₀. The changes in metabolic pathways at IC₂₀ and IC₅₀ of DCBQ were associated with the activation of inositol phosphate, pertaining to the transfer of messages from the receptors of the membrane to the interior as well as with riboflavin. Deactivation of biotin metabolism was recorded, among others. The cells exposed to DCBQ exhibited a concentration-dependent decrease in saccharide concentrations. The concentration of steroids increased when cells were exposed to IC₂₀ and decreased at IC₅₀. Although both chemical factors stressed the cells, DCBQ led to the activation of transporting messages through phosphorylated derivatives of inositol.

CONCLUSION

Our findings provided insights into the impact of the two DBPs on human keratinocytes. Both chemical factors induced energy production perturbations, oxidative stress, and membrane damage.

Metabolomic Profiling Unveils the Impact of Non-Doped and Heteroatom-Doped Carbon Nanodots on Zebrafish (Danio rerio) Embryos

Recently, concern has been raised over the transport, transformation, and fate of carbon nanodots (CNDs) after their release into the environment. Their toxicity towards organisms and humans has recently been addressed as an important issue. In this study, a metabolomic approach was employed to obtain an insight into the effect of CNDs (either pristine or doped with nitrogen and nitrogen/sulfur) on zebrafish. Embryos were exposed to concentrations corresponding to lethal concentration (LC) LC₅₀ (550, 400, and 150 μg mL⁻¹), LC_50/2 (275, 200, and 75 μg mL⁻¹), and LC_50/4 (138, 100, and 38 μg mL⁻¹) of the three CNDs (non-doped, N-doped, and N,S-codoped, respectively) to scrutinize the interactions of the CNDs with the larvae. Numerous differences in the metabolic pathways were recorded in all cases. Seven metabolic pathways were detected in the control larvae. When the larvae were exposed to concentrations equal to LC₅₀, LC_50/2, and LC_50/4 of non-doped CNDs, 12, 12, and 3 metabolic pathways were detected, respectively. In the case of N-doped CNDs, 4, 7, and 4 pathways were detected, while in the case of N,S-codoped CNDs, 8, 5, and 5 pathways were detected when exposed to concentrations of LC₅₀, LC_50/2, and LC_50/4, respectively. In all cases, certain metabolic pathways were altered while others were either down-regulated or up-regulated. Some of these changes include the activation of alanine, aspartate, and glutamate metabolism, aminoacyl-tRNA biosynthesis, butanoate metabolism, D-glutamine, and D-glutamate metabolism, glutathione metabolism, selenoamino acid metabolism, valine, leucine, and isoleucine degradation pathways. Moreover, the deactivation of starch and sucrose metabolism, the glycine, serine, and threonine metabolism, among others, were recorded. Our findings underline the importance to further study the impact of CNDs on marine organisms. As zebrafish has been shown to share many similarities with humans in bioprocesses and genome, it can be assumed that CNDs may also pose a threat to human health.

Induced toxicity in early-life stage zebrafish (Danio rerio) and its behavioral analysis after exposure to non-doped, nitrogen-doped and nitrogen, sulfur-co doped carbon quantum dots

In this study, the effects of doping of CQDs with alternative functional groups (dopants) were evaluated through embryonic development of zebrafish (Danio rerio). The CQDs were synthesized using simple and low-cost sources: Non-doped (citric acid was used as the carbon source), nitrogen-doped (N-doped) and nitrogen, sulfur-co-doped (N,S-doped). The CQDs induced significant toxicity to zebrafish (>150 μg/mL) and the toxic effects were dose-dependent. The N,S-doped CQDs were the most toxic (LD50 = 149.92 μg/mL), followed by the N-doped CQDs (LD50 = 399.95 μg/mL) while the non-doped CQDs were the least toxic (LD50 = 548.48 μg/mL) of the three. The growth rate (GR) was affected following the toxicity pattern (GR_NS-doped<GR_N-doped<GR_non-doped <GR_blanc), which, in turn, greatly depends on the type of dopant. Morphological malformations, such as pericardial edema, yolk sac edema, tail and spinal curvature were observed to zebrafish embryos as the toxicity, concentration and exposure time to the nanomaterial increased. Behavioral analysis showed that locomotor activity increases as the toxicity of the nanomaterial rises. The differences in toxicity, growth rate and malfunctions of CQDs were attributed to their doping with different heteroatoms. The N,S-doped CQDs, unequivocally, exhibited the most pronounced effects.

Sponges and Sponge-Like Materials in Sample Preparation: A Journey from Past to Present and into the Future

Even though instrumental advancements are constantly being made in analytical chemistry, sample preparation is still considered the bottleneck of analytical methods. To this end, researchers are developing new sorbent materials to improve and replace existing ones, with the ultimate goal to improve current methods and make them more efficient and effective. A few years ago, an alternative trend was started toward sample preparation: the use of sponge or sponge-like materials. These materials possess favorable characteristics, such as negligible weight, open-hole structure, high surface area, and variable surface chemistry. Although their use seemed promising, this trend soon reversed, due to either the increasing use of nanomaterials in sample preparation or the limited scope of the first materials. Currently, with the development of new materials, such as melamine sponges, along with the advancement in nanotechnology, this topic was revived, and various functionalizations were carried out on such materials. The new materials are used as sorbents in sample preparation in analytical chemistry. This review explores the development of such materials, from the past to the present and into the future, as well as their use in analytical chemistry.

Cannabinol in the spotlight: Toxicometabolomic study and behavioral analysis of zebrafish embryos exposed to the unknown cannabinoid

Cannabinol (CBN) is a degradation product of the cannabis metabolite Δ9-tetrahydrocannabinol. The CBN concentration in cannabis leaves ranges between 0.1 and 1.6% (w/w of dry weight); it increases as the plant ages and its formation is affected by the storage conditions. As CBN has not been extensively studied so far, the need to examine its impact in vivo is imperative due to the increasing use of cannabis globally. In the study herein, the CBN toxicity, effects on heart physiology, morphological malformations, behavioral changes and alterations in metabolic pathways of zebrafish larvae upon CBN exposure to sublethal concentrations were examined. The LD₅₀ value was estimated at 1.12 mg/l. At the same time, malformations in zebrafish larvae increased significantly in a dose-dependent manner and exposure to CBN concentrations greater than 0.75 mg/l provoked abnormalities like pericardial edema, yolk sac anomalies and tail bending. Concentrations above this threshold resulted in elongated and shorter in width hearts and in separation of ventricle from atrium. The total movement distance and velocity were increased in dark and decreased in light conditions, in a concentration-dependent manner. Our results showed that CBN acts both as a stimulant and a sedative, with larvae to exhibit altered velocity and bradycardia, respectively. The metabolomic analysis revealed alterations mainly to amino acids, which are related to acute toxicity and hint towards systemic metabolic and neuropathophysiological changes. Taken together, our data indicate increased toxic effects as CBN exposure concentration increases, which should be taken into consideration when studying the impact of cannabis on organisms.

Metabolic Fingerprinting of Bacteria Exposed to Nanomaterials, Using Online Databases, NMR, and High-Resolution Mass Spectrometry

Nanomaterials are examined more and more for their antibacterial properties. Herein, we propose a method for assessing the bactericidal properties of nanomaterials against Escherichia coli and Staphylococcus aureus, as well as a method to investigate the metabolic alterations occurring to bacteria, induced by their exposure to nanomaterials. Bacterial metabolome is extracted and metabolic fingerprint is recorded by ¹H-NMR. Using metabolomic databases, the tentative metabolites in the samples are revealed, which are further confirmed by UHPLC-HRMS. Finally, conducting a pathway analysis, the metabolic network is revealed.

Matrix solid-phase dispersion based on magnetic ionic liquids: An alternative sample preparation approach for the extraction of pesticides from vegetables

In this study, we propose, for the first time, the direct use of a magnetic ionic liquid (MIL) in a matrix solid-phase extraction procedure. Because of the magnetic properties, the MIL can be harvested directly after the extraction step, using a magnet, while its hydrophobic nature makes feasible the extraction of analytes. Raw vegetables of high water content can be analyzed without any pretreatment. The viscous nature of the selected MIL assists in blending with the matrix, while its hydrophobicity facilitates easier separation and retrieval. Additionally, no solid dispersing materials or co-sorbents are needed. A simple, low-cost analytical method for the determination of multi-class pesticides residues in raw vegetables was developed, with satisfactory recoveries.

Melamine Sponge Functionalized with Urea-Formaldehyde Co-Oligomers as a Sorbent for the Solid-Phase Extraction of Hydrophobic Analytes

A new procedure for the functionalization of melamine sponge (MeS) with urea-formaldehyde (UF) co-oligomers is put forward. The procedure differs from the typical synthesis of the UF co-polymer, as it employs a base-catalyzed condensation step at certain concentrations of urea and formaldehyde. The produced melamine-urea-formaldehyde (MUF) sponge cubes are hydrophobic, despite the presence of hydrophilic groups in the oligomers. The MUF sponge developed herein is used as a sorbent for the solid-phase extraction of 10 analytes, from 6 different classes (i.e., non-steroidal anti-inflammatory drugs, benzophenones, parabens, phenols, pesticides and musks) and an analytical method is developed for their liquid chromatographic separation and detection. Low limits of quantification (0.03 and 1.0 μg L-1), wide linear ranges and excellent recoveries (92⁻100%) are some of the benefits of the proposed procedure. The study of the synthesis conditions of MUF cubes reveals that by altering them the hydrophilic/lipophilic balance of the MUF cubes can be tuned, hinting towards a strong potential for many other applications.

Enhanced magnetic ionic liquid-based dispersive liquid-liquid microextraction of triazines and sulfonamides through a one-pot, pH-modulated approach

In this study, an enhanced variant of magnetic ionic liquid (MIL)-based dispersive liquid-liquid microextraction is put forward. The procedure combines a water insoluble solid support and the [P₆₆₆₁₄⁺][Dy(III)(hfacac)₄^-] MIL, in a one-pot, pH-modulated procedure for microextraction of triazines (TZs) and sulfonamides (SAs). The solid supporting material was mixed with the MIL to overcome difficulties concerning the weighing of MIL and to control the uniform dispersion of the MIL, rendering the whole extraction procedure more reproducible. The pH-modulation during extraction step makes possible the one-pot extraction of SAs and TZs, from a single sample, in 15 min. Overall, the new analytical method developed enjoys the benefits of sensitivity (limits of quantification: 0.034-0.091 μg L^-1) and precision (relative standard deviation: 5.2-8.1%), while good recoveries (i.e., 89-101%) were achieved from lake water and effluent from a municipal wastewater treatment plant. Owing to all of the above, the new procedure can be used to determine the concentrations of SAs and TZs at levels below the maximum residue limits.

Carbonization of Human Fingernails: Toward the Sustainable Production of Multifunctional Nitrogen and Sulfur Codoped Carbon Nanodots with Highly Luminescent Probing and Cell Proliferative/Migration Properties

A simple yet effective method is employed to prepare multifunctional fluorescent carbon nanodots (CNDs) from human fingernails. The results demonstrate that the CNDs have excellent optical properties and a quantum yield of 81%, which is attributed to the intrinsic composition of the precursor material itself. The CNDs are used to develop an ultrasensitive fluorescent probe for the detection of hexavalent chromium (limit of detection: 0.3 nM) via a combined inner-filter and static mechanism. Moreover, the toxicity of the CNDs over four epithelial cell lines is assessed. A negligible toxicity is induced on the three of the cell lines, whereas an increase in HEK-293 cell viability is demonstrated, granting cell proliferation properties to the as-synthesized CNDs. According to cell cycle analysis, cell proliferation is achieved by enhancing the transition of cells from the S phase to the G2/M one. Interestingly, CNDs are found to significantly promote cell migration, maybe because of their free-radical scavenging ability, making the CNDs suitable for wound healing applications. In addition, relevant experiments have revealed the blood compatibility of the CNDs. Finally, the CNDs were found suitable for cell imaging applications, and all of the aforementioned merits make it possible for them to be used for extraordinary, more advanced biological applications.

Qualitative Alterations of Bacterial Metabolome after Exposure to Metal Nanoparticles with Bactericidal Properties: A Comprehensive Workflow Based on (1)H NMR, UHPLC-HRMS, and Metabolic Databases

Metal nanoparticles (NPs) have proven to be more toxic than bulk analogues of the same chemical composition due to their unique physical properties. The NPs, lately, have drawn the attention of researchers because of their antibacterial and biocidal properties. In an effort to shed light on the mechanism through which the bacteria elimination is achieved and the metabolic changes they undergo, an untargeted metabolomic fingerprint study was carried out on Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria species. The (1)H NMR spectroscopy, in conjunction with high resolution mass-spectrometry (HRMS) and an unsophisticated data processing workflow were implemented. The combined NMR/HRMS data, supported by an open-access metabolomic database, proved to be efficacious in the process of assigning a putative annotation to a wide range of metabolite signals and is a useful tool to appraise the metabolome alterations, as a consequence of bacterial response to NPs. Interestingly, not all the NPs diminished the intracellular metabolites; bacteria treated with iron NPs produced metabolites not present in the nonexposed bacteria sample, implying the activation of previously inactive metabolic pathways. In contrast, copper and iron-copper NPs reduced the annotated metabolites, alluding to the conclusion that the metabolic pathways (mainly alanine, aspartate, and glutamate metabolism, beta-alanine metabolism, glutathione metabolism, and arginine and proline metabolism) were hindered by the interactions of NPs with the intracellular metabolites.

1-Butyl-3-aminopropyl imidazolium-functionalized graphene oxide as a nanoadsorbent for the simultaneous extraction of steroids and β-blockers via dispersive solid-phase microextraction

In this study, we describe the synthesis of graphene oxide functionalized with the ionic liquid 1-butyl-3-aminopropyl imidazolium chloride and its use as an adsorbent for the dispersive solid-phase microextraction (micro SPE) of four anabolic steroids and six β-blockers from aqueous samples of environmental importance, prior to their HPLC-diode array detector analysis. As the ionic liquid is covalently attached to graphene oxide sheets, it is made possible for it to participate in the dispersive micro SPE procedure. The limits of detection and limits of quantification of the proposed method were found to be in the range of 7-23ng/L and between 20 and 70ng/L, respectively. The linearity was satisfactory, with the determination coefficients to range from 0.9940 to 0.9998 while the within- and between-day relative standard deviation of the method ranged between 3.1 and 7.6% and from 4.0 to 8.5%, respectively. In order to test the applicability of the proposed method in real-life samples, the effluent from a municipal wastewater treatment plant as well as natural water samples from two rivers and a lake were collected and analyzed. After the analysis of samples, the effluent from municipal wastewater treatment plant was fortified with the analytes, at concentrations equal to 2 and 10 times the LOQs. Recoveries were calculated after subtracting the native (no-spike) concentrations of analytes, when needed. All the recoveries were in the range of 87-98%. A comparison study attests to the superiority of the developed nanomaterial over graphene oxide and graphene for the dispersive micro SPE of steroids and β-blockers.

In situ trapping of As, Sb and Se hydrides on nanometer-sized ceria-coated iron oxide-silica and slurry suspension introduction to ICP-OES

A procedure is developed for the analysis of sub-μg L(-1) levels of arsenic, antimony and selenium after preconcentration of their hydrides. The study highlights the capability of an aqueous suspension of a nanometer-sized magnetic ceria, in the presence of iodide, to function as a sorbent for the in situ trapping and preconcentration of the hydrides of certain metalloids. After extraction, the material is magnetically separated from the trapping solution and analyzed. A slurry suspension sampling approach with inductively coupled plasma-optical emission spectrometry (ICP-OES) is employed for measurements, as the quantitative elution of the adsorbed metalloids is not feasible. The whole analytical procedure consists of five steps: (i) pre-reduction of As, Sb and Se, (ii) generation of the hydrides AsH3, SbH3 and SeH2, (iii) in situ collection in the trapping suspension of magnetic ceria, (iv) isolation of the particles by applying a magnetic field, and (v) measurement of As, Sb and Se concentrations using ICP-OES. Under the established experimental conditions, the efficiency of trapping accounted for 94 ± 2%, 89 ± 2% and 98 ± 3% for As, Sb and Se, respectively, signifying the effective implementation of the overall procedure. The applicability of the procedure has been demonstrated by analyzing tap and lake water and a reference material (soft drinking water). The obtained analytical figures of merit were satisfactory for the analysis of the above metalloids in natural waters by ICP-OES.

Evaluation of magnetic nanoparticles to serve as solid-phase extraction sorbents for the determination of endocrine disruptors in milk samples by gas chromatography mass spectrometry

A rapid magnetic solid-phase extraction (MSPE) is proposed based on C18-functionalized magnetic silica nanoparticles as sorbents, for the determination of endocrine disruptors - 20 organochlorine pesticides and 6 polychlorinated biphenyls - in milk samples. Magnetic nanoparticles are characterized by several techniques, such as Scanning Electron Microscopy, X-Ray diffraction, Brunauer-Emmett-Teller and Fourier transform-infrared. The MSPE is performed by dispersion of the Fe3O4@SiO2@C18 nanoparticles in milk samples with sonication, after protein precipitation. Then, the sorbent is collected by applying an external magnetic field and the analytes are desorbed by n-hexane. Several parameters affecting the extraction efficiency of target analytes by the magnetic nanoparticles are investigated, including washing and elution solvents, amount of sorbents, time of extraction and elution, sample and elution solvent volume. The proposed method is optimized by means of experimental design and response surface methodology. When coupled with gas chromatography-mass spectrometry detection and under optimum extraction conditions, average recoveries of target analytes are found to be in the range of 79% to 116%. The proposed MSPE-GC-MS analytical method has a linear calibration curve for all target analytes with coefficients of determination to range from 0.9950 to 0.9999. The limits of quantification are found to be between 0.2 and 1μg/L ensuring compliance with the maximum residue limits established by European Commission and Codex Alimentarius, for OCPs and PCBs residues in milk. The proposed method is applied to the determination of target analytes in milk samples from local markets.

Fluoroacetylation/fluoroethylesterification as a derivatization approach for gas chromatography-mass spectrometry in metabolomics: preliminary study of lymphohyperplastic diseases

Metabolic fingerprinting in combination with gas chromatography and multivariate analysis is being extensively employed for the improved understanding of biological changes induced by endogenous or exogenous factors. Chemical derivatization increases the sensitivity and specificity of gas chromatography-mass spectrometry (GC-MS) for polar or thermally labile biological compounds, which bear derivatizable groups. Thus, there is a constant demand for simple methods of derivatization and separation that satisfy the need for metabolite analysis, identifying as many chemical classes of compounds as possible. In this study, an optimized protocol of extraction and derivatization is established as a generally applicable method for the analysis of a wide range of classes of metabolites in urine, whole blood and saliva. Compounds of biological relevance bearing hydroxyl- carboxyl- and amino-groups are derivatized using single-step fluoroacetylation/fluoroethylesterification after proper optimization of the protocol. Subsequently, the developed derivatization procedure is engaged in finding blood metabolic biomarkers, induced by lymphohyperplastic disease, through the metabolomic fingerprinting approach, the multivariate modeling (hierarchical cluster analysis) and GC-MS. Our preliminary, GC-MS-based metabolomic fingerprinting study underlines the contribution of certain metabolites to the discrimination of patients with lymphohyperplastic diseases.

Detection of microcystins in Pamvotis lake water and assessment of cyanobacterial bloom toxicity

Lake Pamvotis is a shallow, eutrophic Mediterranean lake with ecological significance. This paper deals with the evaluation of cyanobacterial toxicity in Lake Pamvotis. ELISA and HPLC revealed the presence of significant amounts of MCYST-LR. Danio rerio bioassay confirmed the toxic nature of the bloom. Cyanobacterial extracts had adverse toxic effects on development of D. rerio. Also, it was shown that cyanobacterial extracts containing environmentally detected concentrations of MCYST can cause reduced survival rate of fish species. The results clearly indicate that cyanobacterial blooms in Lake Pamvotis may be regarded as human and fish health hazard. Continuous monitoring of the lake is suggested, in order to prevent future possible intoxications.

Sensitive determination of pesticides residues in wine samples with the aid of single-drop microextraction and response surface methodology

The multi-residue trace-level determination of six pesticides (diazinon, dimethoate, chlorpyrifos, vinclozolin, fenthion and quinalphos) in wine samples, after their single-drop microextraction (SDME) is presented herein. The extraction procedure was optimized using the multivariate optimization approach following a two-stage process. The first screening experimental design brought out the significant parameters and was followed by a central composite design (CCD) experiment, which revealed the simultaneous effect of the significant factors affecting the SDME process. High level of linearity for all target analytes was recorded with r(2) ranging between 0.9978 and 0.9999 while repeatability (intra-day) and reproducibility (inter-day) varied from 5.6% to 7.4% and 4.9% to 12.5%, respectively. Limits of detection (LODs) and limits of quantification (LOQs) were found to range in the low microg L(-1) level. In general, the developed methodology presented simplicity and enhanced sensitivity, rendering it appropriate for routine wine screening purposes.

Phenolic acids and flavonoids: occurrence and analytical methods

Phenolics are structurally assorted and are generally part of a complex mixture isolated from plant and biological origin matrices. A wide gamut of natural products have been the focus of main study for phenolic compounds while urine and blood are the two main biological fluids that have been analyzed for metabolism studies. Traditional and more advanced techniques have come to prominence for sample preparation, detection, and identification. This review is devoted to a short discussion of the occurrence of phenolic acids and flavonoids, their role in human health, and focuses on a detailed presentation of the analytical methods, concluding with the advantages of analytical methods employed so far and prospects. Strategies and practical aspects for the determination of phenolic acids and flavonoids in biological fluids, beverages, plants, and food are reported. Novel and past applications are provided with significant treatment and detection-related developments on the basis of the employment of separation and non-separation analytical techniques.

Measurements of benzene and formaldehyde in a medium sized urban environment. Indoor/outdoor health risk implications on special population groups

In the present study, the results of a measurement campaign aiming to assess cancer risk among two special groups of population: policemen and laboratory technicians exposed to the toxic substances, benzene and formaldehyde are presented. The exposure is compared to general population risk. The results show that policemen working outdoor (traffic regulation, patrol on foot or in vehicles, etc.) are exposed at a significantly higher benzene concentration (3-5 times) than the general population, while the exposure to carbonyls is in general lower. The laboratory technicians appear to be highly exposed to formaldehyde while no significant variation of benzene exposure in comparison to the general population is recorded. The assessment revealed that laboratory technicians and policemen run a 20% and 1% higher cancer risk respectively compared to the general population. Indoor working place air quality is more significant in assessing cancer risk in these two categories of professionals, due to the higher Inhalation Unit Risk (IUR) of formaldehyde compared to benzene. Since the origin of the danger to laboratory technicians is clear (use of chemicals necessary for the experiments), in policemen the presence of carbonyls in indoor air concentrations due to smoking or used materials constitute a danger equal to the exposure to traffic originated air pollutants.

Simultaneous determination of chlorothalonil and its metabolite 4-hydroxychlorothalonil in greenhouse air: dissipation process of chlorothalonil

An analytical method was developed and tested for the simultaneous determination of chlorothalonil and its main metabolite 4-hydroxychlorothalonil, in airborne samples. High performance liquid chromatography equipped with Ultra-violet detector was used to separate and quantify the analytes. Glass microfibre filters for the collection of the analytes' particles were tested. Solid sorbents, such as Tenax, Florisil, XAD-2 and silica gel, were studied to find out the most suitable material for the collection of the analytes in the gas phase. The results have shown that only chlorothalonil was trapped in the vapor phase with highest results obtained when silica gel was the sorbent of choice. Linearity was demonstrated in a wide concentration range 0.01-10.00 mg L(-1). Recoveries from spiked glass microfibre filters and silica gel cartridges for chlorothalonil and 4-hydroxychlorothalonil were almost quantitative. The quantification limits were calculated to be 8.4 and 19.6 ng m(-3) in air for chlorothalonil and 4-hydroxychlorothalonil, respectively. The two analytes spiked on the GF/A filters and silica gel cartridges were proven to be stable for more than 15 days, at 4degrees C and ambient temperature. The applicability of the present method was demonstrated by the analysis of the chlorothalonil and its metabolite in greenhouse air.

Extraction, separation, and detection methods for phenolic acids and flavonoids

The impetus for developing analytical methods for phenolic compounds in natural products has proved to be multifaceted. Hundreds of publications on the analysis of this category of compounds have appeared over the past two decades. Traditional and more advanced techniques have come to prominence for sample preparation, separation, detection, and identification. This review provides an updated and extensive overview of methods and their applications in natural product matrices and samples of biological origin. In addition, it critically appraises recent developments and trends, and provides selected representative bibliographic examples.

Theoretical analysis and experimental evaluation of headspace in-drop derivatisation single-drop microextraction using aldehydes as model analytes

In-drop derivatisation single-drop microextraction approach can constitute, to a certain degree, a low-cost reasonable alternative to the well-known on-fibre solid-phase microextraction. The headspace mode integrates extraction, preconcentration and derivatisation into a single step from the headspace of a sample. In this study, two low-molecular-weight aldehydes are derivatised in a hanging drop containing 2,4,6-trichlorophenylhydrazine, in a headspace single-drop microextraction configuration system. The single organic drop, dispersed in gas phase, is well covered in this study as a locale of the main reaction. The measurement of diffusion and kinetic parameters and their relationship were designed to reveal, for the first time, inherent mechanistic aspects in such an analytical system. The two-film theory of mass transfer is used to discuss the mechanism along with the calculation of characteristic times and specific rates of absorption. All these, together with certain experimental data may ascertain whether the overall process is reaction rate dependent or limited by mass transfer in the gas phase, at the air-water and air-organic interface or in the organic phase. The descriptors of mass transfer and chemical reaction in a single drop are critically reviewed and reconsidered and the practical aspects for the analysis of volatile organic compounds are highlighted. Relative standard deviations for both aldehydes were 3.4% (n=5) and 4.9% (n=5) for 1 microM of hexanal and 0.3 microM of formaldehyde, respectively. Detection limits for aqueous samples were 0.1 and 0.03 microM for formaldehyde and hexanal, respectively.

Determination of dithiocarbamate fungicide propineb and its main metabolite propylenethiourea in airborne samples

A simple, rapid and sensitive GC-MS method for the determination of dithiocarbamate fungicide propineb [polymeric zinc propylenebis (dithiocarbamate)] and an improved HPLC procedure for the simultaneous determination of its main metabolite, propylenethiourea, and ethylenethiourea, the main metabolite of all ethylenedithiocarbamates, in airborne samples are described. The method for the analysis of propineb involves the evolution of carbon disulfide (CS(2)), under acidic conditions in the presence of stannous chloride, extraction of the generated CS(2) into a layer of isooctane which is then analyzed for CS(2) content by GC-MS in SIM mode. Under the optimum conditions, the retention time of CS(2) was 1.89 min and the total time of chromatographic analysis was 5 min. Recoveries from spiking glass microfibre filters (GF/A) and silica gel filters were 86+/-7 (n=9) and 89+/-4 (n=9), respectively. The limit of detection is 0.7 ng per filter, which is equivalent to about 0.8-1.0 ng m(-3) in air. In parallel, an HPLC method with ultraviolet detection is presented for the simultaneous analysis of the metabolites. Separation of the two metabolites was attained in less than 5 min. Recoveries from spiking GF/A and silica gel filters for ethylenethiourea were 100+/-1 (n=3) and 98+/-2 (n=3), respectively, while for propylenethiourea were 102+/-1 (n=3) and 98+/-1 (n=3), respectively. The detection limits are about 36-43 and 40-49 ng m(-3) in air for ethylenethiourea and propylenethiourea, respectively. All the analytes spiked in the filters are proven to be stable for more than one month, at -4 degrees C.

In-drop derivatisation liquid-phase microextraction assisted by ion-pairing transfer for the gas chromatographic determination of phenolic endocrine disruptors

A novel in-drop derivatisation liquid-phase microextraction procedure with an ion-pairing agent is developed and optimised for the extraction of endocrine-disrupting chemicals. The ethyl esters of the analytes were rapidly formed in the organic drop and analysed by gas chromatography. The effects of various parameters such as rate and time of agitation, ion-pairing agent and reactant concentration, pH and temperature were studied systematically to optimise the process and bring out the locale of reaction in the organic drop. A study of the mechanistic pathways of the overall procedure is attempted leading to interesting findings and delineating important points of the kinetics and mechanism. A mechanistic model is proposed on the basis of the theory of mass transfer with chemical reaction in two liquid phases. The O-ethoxycarbonyl derivatisation appears to take place in the bulk organic phase. The system provides insight into the first reported analytical case of single-drop extraction-preconcentration-derivatisation assisted by an ion-pairing transfer and has all of the interesting facets of chemical reaction in which the role of mass transfer comes into picture. The analytical features of the method are acceptable and the overall relative standard deviations of the intra-day repeatability (n=5) and inter-day reproducibility were <3.9% and <5.4%, respectively, for gas chromatography-mass spectrometry analyses and <4.3% and <7.1% for gas chromatography-flame ionisation detection analyses. The method was applicable to urine and surface water samples. The LODs ranged between 0.2-1.3 ng mL(-1) and 8.5-26.5 ng mL(-1) for GC/MS and GC/FID analyses, respectively.

Chemical and physicochemical profile of wastewaters produced from the different stages of Spanish-style green olives processing

The main purpose of the processing of table olives is the removal, at least partially, of the natural bitterness of the fruit in order to render it edible. The preparation of Spanish-style green olives after harvesting involves cleaning followed by debittering using NaOH solution, washing with water, a lactic acid fermentation step and finally canning. Wastewaters originating from table olives processing industries pose an important environmental threat, as they are characterized by a very high organic load and high concentration of phenolic compounds, which are toxic to living organisms. In this communication, the chemical and physicochemical profile of wastewaters produced from the different stages of Spanish-Style green olives processing was investigated. Phenolic compounds, organic acids, amino acids and total sugars along with common physicochemical parameters were determined in order to appraise the specific features of each individually produced wastewater.

Improved method for the in vitro assessment of antioxidant activity of plant extracts by headspace solid-phase microextraction and gas chromatography–electron capture detection

The simultaneous monitoring of malondialdehyde, pentanal and hexanal, final products of lipid peroxidation is reported, using a headspace solid-phase microextraction (HS-SPME) technique with on-fibre derivatisation. The aldehydes are extracted and subjected to on-sorbent derivatisation into stable hydrazones with 2,4,6-trichlorophenylhydrazine (TCPH) and analyzed. The degree of inhibition of oxidation is performed by monitoring the chlorinated hydrazones after thermal desorption, by gas chromatography-electron capture detection. The procedure was employed to evaluate in vitro the antioxidant activity of Hypericum perforatum L. extracts and of the well-known antioxidant vitamin E following induction of oxidation of sunflower oil, as a model lipid system. Prior to the measurement of antioxidant activity, the optimal process conditions, i.e. headspace volume, temperature, agitation, extraction/derivatisation time and desorption time and temperature were properly established. Aqueous extracts of H. perforatum L. exhibited the highest antioxidative effect. The method is shown to be promising for screening purposes for antioxidant substances and natural extracts.

Gas chromatographic determination of amino acids via one-step phase-transfer catalytic pentafluorobenzylation–preconcentration

The gas chromatographic determination of amino acids via their simultaneous extraction, preconcentration and pentafluorobenzylation is reported. Using phase-transfer catalysis (PTC), the amino acids under study were transformed to their pentafluorobenzyl adducts. The method was tested for different catalysts and tetrabutylammonium bromide provided favorable features in comparison to the other PTCs. The derivatization procedure was optimized and the best reaction conditions are given. With the exception of arginine, 19 amino acids were converted to volatile derivatives and analyzed with GC/MS and GC/FID at low concentration levels with acceptable sensitivity and good reproducibility. The LODs were found to range from 0.7 to 2.3microM for the GC/MS analyses and from 1.7 to 6.9microM for GC/FID analyses. The method practicability and applicability were confirmed by the analysis of urine, fruit juice and wheat flour for the determination of the amino acids under study. Protein-bound amino acids were analyzed after an alkaline hydrolysis step with 5M NaOH applying this method to wheat flour with an overall procedure duration less than 12h. The optimized protocol was applied to these samples without any pretreatment and their amino acid concentrations were calculated from the appropriate calibration plots.

Photophysical properties of Hypericum perforatum L. extracts--novel photosensitizers for PDT

We report the preparation of the methanolic extract (ME), and polar methanolic fraction (PMF) from the plant Hypericum perforatum L. The extracts contain various photosensitizing constituents such as naphthodianthrone derivatives (in 1.37% w/w), and chlorophylls (in 0.08% w/w). Upon light emission these constituents can be activated, providing photodynamic properties to the extracts, and making them a potent, new class, natural photosensitizers for use in photodynamic therapy (PDT), and photodynamic diagnosis (PDD). The absorbance spectra of the extracts are similar to the spectrum of hypericin, the main naphthodianthrone identified within, with two major bands at 548 and 590 nm. The fluorescence spectra in ethanol exhibit two main bands around 595 and 640 nm, in accordance with the spectrum of pure hypericin. The fluorescence intensity of PMF at 595 nm is only eight times less than the intensity of pure hypericin at the same wavelength, even though its hypericin concentration is only 0.57% w/w. The dependence of the PMF fluorescence signal on the pH of the medium, alone and in comparison with the signal of hypericin, has been investigated. PMF signal fades steadily, and smoothly both in acidic, and basic environment.

Single-drop liquid-phase microextraction for the determination of hypericin, pseudohypericin and hyperforin in biological fluids by high performance liquid chromatography

The analysis of hypericin, pseudohypericin (collectively called in this study hypericins) and hyperforin in biological fluids is reported using single-drop liquid-phase microextraction in conjunction with HPLC-UV-fluorescence detection. A new option for analysis of the active principle constituents in biological samples is proposed, reducing the steps required prior to analysis. There are several parameters which determine the mass transfer such as the extraction solvent, drop and sample volumes, extraction time and temperature, pH and ionic strength, stirring rate and depth of needle tip in the bulk solution. These parameters were chosen to optimize the performance in the current study. The method was validated with respect to precision, accuracy and specificity. The intra-day precision values were below 2.3% for the high concentration level of control samples and 6.2% for the low level. The respective inter-day precision values were calculated to be below 4.4 and 7.1%, respectively, for the two concentration levels. Accuracy of the method, calculated as relative error, ranged from -2.6 to 7.0%. It was demonstrated that as long as the extraction procedure is consistently applied, quantitative analysis is performed accurately and reproducibly in human urine and plasma samples. Limits of quantitation (LOQs) in urine were calculated to be 3, 6 and 12 ng/ml for pseudohypericin, hypericin and hyperforin, respectively. Slightly higher limits were measured in plasma, i.e. 5, 12 and 20 ng/ml, for the respective analytes.

The lipophilic extract of Hypericum perforatum exerts significant cytotoxic activity against T24 and NBT-II urinary bladder tumor cells

Hypericum perforatum L. (St. John's wort) is a medicinal plant used for many pathologies, especially for the treatment of mild to moderate depression. In the present study we have investigated the cytotoxic activity of the locally collected (Epirus region) Hypericum perforatum L. against cultured T24 and NBT-II bladder cancer cell lines. The lipophilic extract of the herb, prepared using petroleum ether, induced apoptosis displaying LC(50) values at concentrations as low as 4 and 5 microg/mL. A fraction of this extract displayed 60 % cell growth inhibition at a concentration of 0.95 microg/mL. Evaluating the importance of various biologically active components of the extract, it was found that hypericins (hypericin, pseudohypericin, etc.) were identified only in the methanolic (lipophobic) extract of the herb, and not in the active lipophilic extract. In addition, hyperforin concentrations in the lipophilic extract and its most active fraction, were 0.94 microg/mL, and 0.17 microg/mL, respectively, while the active cytotoxic concentration of pure hyperforin appeared in the range of 1.8 microg/mL - 5.0 microg/mL. Therefore, pure hyperforin does not seem to contribute significantly to the cytotoxicity activity. Chlorophylls were identified in low, not significantly different, concentrations in all extracts and fractions and were not correlated to the biological activity. Owing to the combination of significant cytotoxic activity, natural abundance and low toxicity, the lipophilic extract of Hypericum perforatum holds the promise of being an interesting, new, antiproliferative agent against bladder cancer that deserves further investigation.

Determination of plasma, urine, and bovine serum albumin low-molecular-weight carbonyl levels by capillary gas chromatography with electron-capture and mass-selective detection

Peroxidation of lipids produces low-molecular-weight carbonyl compounds, which are reactive with biological nucleophiles. The analysis of these compounds is often difficult. A multicomponent method for the determination of 11 of them in biological samples is reported. The samples are subjected to a pretreatment-derivatization procedure followed by gas chromatographic analysis with either electron-capture detection (ECD) or mass-selective detection (MSD) in the selected-ion monitoring mode. The procedure involves derivatization of the analyte with 2,4,6-trichlorophenylhydrazine, extraction with n-hexane, and separation of the derivatization products on a nonpolar gas chromatographic column. The concentration of the derivatization reagent, pH, reaction time, temperature, and presence of extraneous ions were investigated to determine the optimal derivatization conditions. Under these conditions, the method allows for the selective detection of low-molecular-weight carbonyl compounds at femtomole levels in several biological materials such as plasma, urine, and bovine serum albumin without interferences. The limits of detection were in the ranges 0.01-0.2 microM for ECD and 0.15-1.5 microM for MSD. The mean procedural recoveries obtained during the method validation were within the range 85-95% and the intra- and interassay standard deviations do not exceed 4.6 and 6.1%, respectively.

Ultrasonic-assisted derivatization reaction of amino acids prior to their determination in urine by using single-drop microextraction in conjunction with gas chromatography

A derivatization-extraction method that avoids tedious preconcentration steps is established in order to determine amino acids accurately at nanogram levels. The method involves conversion of the analytes of concern to N(O,S)-ethoxycarbonyl amino acid ethyl esters and subsequent extraction by single-drop microextraction (SDME) followed by GC analysis. The reaction proceeds smoothly and rapidly under ultrasonication which removes the bubbles from the bulk solution. Precision is acceptable and 12 non-hydrolyzed amino acids can be determined in urine in this manner. As long as the extraction conditions are consistently applied, quantitative analysis can be performed accurately. The limits of detection were satisfactory in the range 0.010-0.025 microg/ml for GC-FID and 0.26-68 ng/ml for GC-MS(SIM) with 1 ml sample volume.