Quantification of selected furocoumarins by high-performance liquid chromatography and UV-detection: Capabilities and limits

Extraction and Chromatographic Approaches for Coumarin, Furocoumarin, and Polymethoxyflavone Characterization in Foods

Oxygen heterocyclic compounds play a beneficial role in plants, and their presence in foods, such as Citrus fruits, cinnamon, carrots, and parsley, has been documented in recent years. Published research articles reported several extractions and chromatographic techniques for their determination. The aim of this review was to take into consideration the research articles published from 2016 to 2024 in which the authors developed extraction and chromatographic analysis methods of oxygen heterocyclic compounds in foods. The objective of this review was to assist researchers in choosing the best approach for their future work by identifying all the possible approaches to characterize coumarins, furocoumarins, and polymethoxyflavones in foodstuffs.

Determination of Oxygen Heterocyclic Compounds in Foods Using Supercritical Fluid Chromatography-Tandem Mass Spectrometry

The aim of this research was to determine oxygen heterocyclic compounds in twenty-six Citrus- and cinnamon-flavoured foods using supercritical fluid chromatography in combination with triple-quadrupole mass spectrometry (SFC-QqQ-MS). According to the authors' knowledge, this is the first report on the determination of these molecules in foods by means of the SFC-QqQ-MS technique. The analytical technique normally used for their determination in foods is liquid chromatography coupled with a photodiode array detector. However, supercritical fluid chromatography is proving to be a valid alternative approach to investigating coumarins, furocoumarins and polymethoxyflavones. According to the results presented herein, each sample analysed showed the presence of molecules of interest. Coumarin was found in all the cinnamon-flavoured samples analysed in a low concentration. The presence of oxygen heterocyclic compounds in all the Citrus-flavoured samples, according to the label, comfirmed that the foods selected for this research article were prepared with Citrus fruits. Among the samples analysed, mandarin juice was the richest in bioactive compounds, representing a good source of polymethoxyflavones in a diet.

Hidden threat lurking in extensive hand hygiene during the Covid-19 pandemic: investigation of sensitizing molecules in gel products by hyphenated chromatography techniques

During the Covid-19 pandemic, health agencies worldwide have recommended frequent handwashing and sanitizing. A variety of hand gel products were made available on the market, often with fragrances added to curtail the strong smell of alcohol. Commonly used Citrus fragrances contain volatile aroma constituents and non-volatile oxygen heterocyclic compounds (OHCs), consisting mostly of polymethoxyflavones, coumarins, and furocoumarins. The latter have long been investigated for their phototoxic properties, and their safety as cosmetic product ingredients has been debated recurrently. To this concern, twelve commercial Citrus-scented products were investigated in this study. An extraction method was optimized for thirty-seven OHC compounds, obtaining absolute mean recovery values in the 73.5-116% range with only few milliliters of solvent consumption. Analysis by ultra-high-pressure liquid chromatography with tandem mass spectrometry detection evidenced that three samples did not conform to the labeling requirements for fragrance allergens (coumarin) laid down by the European Union Regulation on Cosmetic Products. The total furocoumarin (FC) content of the samples investigated was in the 0.003-3.7ppm range, with some noteworthy exceptions. Specifically, in two samples, the total FCs were quantified as 89 and 219 ppm, thus exceeding the safe limits recommended up to a factor of 15. Finally, the consistency of the volatile fingerprint attained by gas chromatography allowed drawing conclusions on the authenticity of the Citrus fragrances labeled, and several products did not conform to the information reported on the label concerning the presence of essential oils. Besides the issue of product authenticity, analytical tools and regulatory actions for widespread testing of hand hygiene products are urgent, to protect consumers' health and safety.

Supercritical fluid chromatography-tandem mass spectrometry of oxygen heterocyclic compounds in Citrus essential oils

Oxygen heterocyclic compounds are secondary metabolites mainly present in the non-volatile fraction of cold-pressed Citrus essential oils. Under this denomination are included coumarins, furocoumarins, and polymethoxyflavones. These compounds possess numerous beneficial properties for human health, but the ingestion of large amounts of coumarins is often related to toxic effects, whereas the phototoxicity caused by furocoumarins and UVA exposure has been well known for a long time. This research has been aimed at the validation of an analytical approach, based on supercritical fluid chromatography coupled to tandem mass spectrometry, for the analysis of OHCs in Citrus essential oils. Among eight columns tested, packed with different stationary phases, the pentafluorophenyl allowed the best baseline separation in 8 min and by using less than 10% of methanol. Calibration curves of twenty-eight standards (coumarins, furocoumarins, polymethoxyflavones) were constructed on spiked lemon distilled essential oil and the method was validated according to the EURACHEM guidelines, by calculating linearity, limit of detection (LoD), limit of quantification (LoQ), accuracy, intra-day, and inter-day precision. Specifically, recoveries were in the 80.0-118.6% range, regression coefficients were between 0.9904 and 0.9998, the LoDs were in the 0.0004-0.0470 mg kg^-1 range, the LoQs were in the 0.0014-0.1536 mg kg^-1 range, and coefficients of variation were between 0.3 and 2.6% (intra-day) and 1.1 and 7.4% (inter-day). The quantitative profiles of thirteen cold-pressed Citrus essential oils were determined.

Analysis and classification of peanuts with fungal diseases based on real-time spectral processing

The study presents an approach to the analysis and classification of peanuts performed in order to detect kernels with fungi diseases, i.e. kernels prone to contamination with mycotoxigenic Aspergillus flavus (Aspergillus parasiticus). The aim of this study was to evaluate the effectiveness of luminescent spectroscopy with a violet laser (405 nm wavelength) as the excitation source of the fluorescence when applied for real-time detection of mould in peanuts performed by means of multispectral processing based on machine learning methods. We suggest a laboratory unit used to form, register, and process the luminescence spectra of peanuts in visible and near-infrared wavelength ranges in the real-time mode. The study demonstrated that contaminated peanuts have increased luminous intensity and show a redshift in the fluorescence peaks of the contaminated samples as compared to the pure ones. The difference in the fluorescence spectra of pure and contaminated kernels is compatible with the results obtained when traditional UV-light sources are used (365 nm). To classify peanuts by their spectral characteristics, neural network algorithms were used combined with dimensionality reduction methods. The paper presents the probabilities of incorrect recognition of the peanuts' type depending on the number of relevant secondary features determined when reducing the dimensionality of the initial data. When 10 spectral components were used, the error ratios were 0.7% or 0.3% depending on the method of reducing the dimensionality of the initial data.

Novel ionic liquid based dispersive liquid-liquid microextraction for the extraction of bergapten and bergamottin in hydroalcoholic cosmetic formulations

This study reports the synthesis of the room temperature ionic liquid 1-propyloxy-3-ethoxyimidazolium bis(trifluoromethane)sulfonamide for the extraction of bergapten and bergamottin from hydroalcoholic cosmetic samples by means of dispersive liquid-liquid microextraction. Molecular structures of the final ionic liquid as well as intermediate products were confirmed by nuclear magnetic resonance spectroscopy. Analyses were performed with high performance liquid chromatography with subsequent diode array and fluorescence detection. The extraction procedure was optimized with the design of the experiment using a three level Box-Behnken approach. Applying the synthesized room temperature ionic liquid as extraction medium, the optimized workflow demonstrated high recoveries illustrating powerful isolation properties for furanocoumarins, which are comparable or even better than using typical extraction solvents. Moreover, the workflow was validated regarding instrumental limits, linearity, accuracy, repeatability and stability of analytes according to international guidelines. To test its applicability on a more complex matrix, hydroalcoholic cosmetic samples were analyzed. Despite highly complex matrices, accurate and precise quantification in the range of 0.04-1.25 μg mL-1 was achieved in spiked and unspiked samples, with bias <10% and RSD < 12%.

Evaluation of furanocoumarins from seeds of the wild parsnip (Pastinaca sativa L. s.l.)

Although the wild parsnip (Pastinaca sativa L. s.l.) fruits are known to contain linear and angular furanocoumarins, the individual components of the seeds have not been fully identified and quantitated, and, in the case of immature seeds, reported. In view of this, the main furanocoumarin compounds were extracted using pyridine, and were isolated using semi-preparative high-performance liquid chromatography. The structural elucidation of isolated compounds was done based on detailed spectral analysis conducted by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI/MS), ¹H and ¹³C NMR and, where possible, by gas chromatography-mass spectrometry (GC-MS). The quantitative analysis of furanocoumarin compounds in the wild parsnip was conducted by analytical ultra-performance liquid chromatography (UPLC-DAD), calculated against the standard curves of isolated compounds. The total yields of furanocoumarin compounds from the seeds after extraction with pyridine were 107.2-222.8 mg g^-1 (fresh weight) and 50.2-66.4 mg g^-1 (soluble dry matter). Thirteen furanocoumarins were identified. The main compounds (percentage in FW) in immature seeds were bergapten (40.8), pimpinellin (10.5), methoxsalen (5.7), isopimpinellin (4.3), imperatorin (3.2), and phellopterin (7.2). Seven constituents previously not described in P. sativa seeds and its products were identified, namely, byakangelicol (14.4), heraclenin (8.5), isobergapten (2.5), byakangelicin (1.3), heraclenol (0.5), psoralen (0.3), and isobyakangelicin (0.8). The latter is a new compound of the Apiaceae family. Extraction of immature seeds using pyridine gave a much higher yield and a greater variety of furanocoumarins. This indicates that the wild parsnip, along with other Apiaceae family plants, may be an important source of bioactive compounds.

Determination of citrus juice coumarins, furanocoumarins and methoxylated flavones using solid phase extraction and HPLC with photodiode array and fluorescence detection

A synergistic combination of analytical techniques was developed for the simultaneous determination of the three most biologically active chemical families in citrus juices: methoxylated flavones, coumarins, and furanocoumarins. No rapid methodology has been available to determine them together. A solid phase extraction concentrated these groups and a ternary reverse phase HPLC gradient completely resolved them from other juice components. Two coumarins, isomeranzin and osthole, were identified in a sweet orange (C. sinensis) cultivar, Changyecheng, for the first time. Pummelo juice was characterized by coumarin and furanocoumarin epoxides such as meranzin and epoxybergamottin. No epoxides were observed in the more acidic juices. Added furanocoumarin epoxides hydrolyzed rapidly in the most acidic juices. The ratios of the UV peak areas at 320 nm to the fluorescence emission peaks as well as the ratio of fluorescence emission peaks at 450-400 nm could be used to identify chromatographic peaks.

A Method for LC-MS/MS Profiling of Coumarins in Zanthoxylum zanthoxyloides (Lam.) B. Zepernich and Timler Extracts and Essential Oils

The metabolites from the coumarin class, present in tissues of plants belonging mainly to the Rutaceae and Apiaceae families, included compounds with high chemical diversity such as simple coumarins and furocoumarins. These health-promoting components are recognized for their valuable biological activities in herbal preparations but also for their phototoxic effects. In this work, a targeted liquid chromatography (LC) coupled with tandem mass spectrometry (MS²) was developed for the screening of 39 reference standards of coumarins and furocoumarins in essential oils and plant extracts. Chromatographic separation was accomplished on reversed phase column using water/acetonitrile as the mobile phase and detection was performed on a hybrid QqQ/linear ion trap spectrometer fitted with an atmospheric pressure chemical ionization (APCI) source operating in positive ion mode. This analytical approach was applied to investigate the coumarin compositions of fruit essential oils and methanolic extracts obtained from separated parts (fruit, leaf, stem, trunk, and root) of Zanthoxylum zanthoxyloides. Ten coumarins and six furanocoumarins were reported in this species and data analyses were used to assess the suitability of these compounds to the metabolomics-based differentiation of plant organs. The quantification criteria of the metabolites in extract samples included linearity, limit of quantification, limit of detection, and matrix effect were validated. As reported for other species of the Rutaceae family, the concentration of coumarins was drastically higher in Z. zanthoxyloides fruits than in other plant organs.

The pharmacokinetics, bioavailability and excretion of bergapten after oral and intravenous administration in rats using high performance liquid chromatography with fluorescence detection

A sensitive, specific, reproducible and optimized high performance liquid chromatography with fluorescence detection (HPLC-FLD) method for the determination of bergapten in rat plasma was established and applied to the pharmacokinetic and bioavailability study in rat after oral and intravenous administration of bergapten. The method was also successfully applied to the excretion study of bergapten after an oral administration of bergapten at a dose of 15 mg kg^-1 to rats. The sample preparation was achieved using liquid-liquid extraction. Isoimperatorin was used as the internal standard (IS). The analytes were detected by using fluorescence detection at an excitation and emission wavelength of 288 and 478 nm, respectively. Using aqueous formic acid (0.1 %, v/v) and acetonitrile as the mobile phase, the chromatographic separation was achieved on a Hedera™ ODS column at a flow rate of 1 mL min^-1. The lower limit of quantitation (LLOQ) of bergapten was 2 ng mL^-1. The HPLC-FLD method was successfully applied to the pharmacokinetic, bioavailability and excretion study of bergapten in rats.Graphical abstractAn high performance liquid chromatography with fluorescence detection (HPLC-FLD) method for the pharmacokinetic and bioavailability study in rat after administration of bergapten.

Oxygenated heterocyclic compounds to differentiate Citrus spp. essential oils through metabolomic strategies

This study aimed to characterise and discriminate 44 authenticated commercial samples of citrus essential oils (EO) from seven species (bergamot, lemon, bigarade, orange, mandarin, grapefruit, lime) by analysing the non-volatile oxygenated heterocyclic compounds (OHC) by UHPLC/TOF-HRMS, multivariate data analysis (PCA, PLS-DA) and metabolomic strategies; the OHC fraction includes coumarins, furocoumarins, and polymethoxylated flavonoids. Two different approaches were adopted: (i) targeted profiling based on quantifying 18 furocoumarins and coumarins, some of which are regulated by law, and (ii) targeted fingerprinting based on 140 OHCs reported in citrus essential oils, from which 38 discriminant markers were defined. This approach correctly discriminated the Citrus species; its "sensitivity" to relatively low adulteration rate (10%) was highly satisfactory. The proposed method is complementary to that of analysing the citrus EO volatile part by GC techniques.