CT, US and MRI of xanthine urinary stones: in-vitro and in-vivo analyses.

BACKGROUND: Xanthine urinary stones are a rare entity that may occur in patients with Lesch-Nyhan syndrome receiving allopurinol. There is little literature describing imaging characteristics of these stones, and the most appropriate approach to imaging these stones is therefore unclear. We performed in-vitro and in-vivo analyses of xanthine stones using computed tomography (CT) at different energy levels, ultrasound (US), and magnetic resonance imaging (MRI). METHODS: Five pure xanthine stones from a child with Lesch-Nyhan were imaged in-vitro and in-vivo. CT of the stones was performed at 80 kVp, 100 kVp, 120 kVp and 140 kVp and CT numbers of the stones were recorded in Hounsfield units (HU). US of the stones was performed and echogenicity, acoustic shadowing and twinkle artifact were assessed. MRI of the stones was performed and included T2-weighted, ultrashort echo-time-weighted and T2/T1-weighted 3D bFFE sequences and signal was assessed. RESULTS: In-vitro analysis on CT demonstrated that xanthine stones were radiodense and the average attenuation coefficient did not differ with varying kVp, measuring 331.0 ± 51.7 HU at 80 kVp, 321.4 ± 63.4 HU at 100 kVp, 329.7 ± 54.2 HU at 120 kVp and 328.4 ± 61.1 HU at 140 kVp. In-vivo analysis on CT resulted in an average attenuation of 354 ± 35 HU. On US, xanthine stones where echogenic with acoustic shadowing and twinkle artifact. On MRI, stones lacked signal on all tested sequences. CONCLUSION: Xanthine stone analyses, both in-vitro and in-vivo, demonstrate imaging characteristics typical of most urinary stones: dense on CT, echogenic on US, and lacking signal on MRI. Therefore, the approach to imaging xanthine stones should be comparable to that of other urinary stones.

Modified graphene-silica as a sorbent for in-tube solid-phase microextraction coupled to liquid chromatography-tandem mass spectrometry. Determination of xanthines in coffee beverages.

Given the increasing need for analyzing natural or contaminating compounds in complex food matrices in a simple and automated way, coupling miniaturized sample preparation techniques with chromatographic systems have become a growing field of research. In this regard, given the low extraction efficiency of conventional sorbent phases, the development of materials with enhanced extraction capabilities is of particular interest. Here we present several synthesized graphene-based materials supported on aminopropyl silica as sorbents for the extraction of xanthines. The synthesized materials were characterized by infrared spectroscopy and scanning electron microscopy. Aminopropyl silica coated with graphene oxide and functionalized with octadecylsilane/end-capped (SiGOC18ecap) showed the best performance for xanthines extraction. Hence, this material was employed as an in-tube solid phase microextraction (in-tube SPME) device coupled online with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and applied for the analysis of xanthines in roasted coffee samples. Extraction parameters and detection conditions were optimized. The method showed low limits of quantification (0.3-1.0 µg L-1), precision as relative standard deviation (RSD) values lower than 10%, recoveries between 73 and 109%, and pre-concentration factors from 5.6 to 7.2. Caffeine was determined in all ground roasted and instant coffee samples, in a wide range (0.9 to 36.8 mg g-1), and small amounts of theobromine and theophylline were also detected in some samples. This work demonstrated that functionalized graphene-based materials represent a promising new sorbent class for in-tube SPME, showing improved extraction capacity. The method was efficient, simple, and fast for the analysis of xanthines, demonstrating an excellent potential to be applied in other matrices.

Mass spectrometry imaging of thin-layer chromatography plates using laser desorption/low-temperature plasma ionisation.

Thin-layer chromatography (TLC) is a classic method for the separation and analysis of complex mixtures. Biological assays, chemical derivatisation and spectroscopy techniques are compatible with TLC and provide extra information about isolated compounds. However, coupling TLC to mass spectrometry is hampered by the difficulty to desorb the analytes from the silica surfaces. In this study, we used a multimodal ion source for laser desorption (LD) and low-temperature plasma (LTP) post-ionisation. Efficient desorption was reached by covering the TLC plates with activated carbon. Regions of interest can be analysed by spots, by lines or by area. We show the separation of methylxanthines from coffee, tea and cocoa preparations by TLC, with subsequent mass spectrometry imaging (MSI). Using a lateral resolution of 400 µm × 400 µm, allowed the acquisition of 21 895 spectra in 2.4 h (2.5 pixels per s). Further, we demonstrate the possibility of direct mass fragmentation studies and quantification. We mounted the system on an Open LabBot with a theoretical lateral resolution of 12.5 µm and performed the visualisation of ions of interest and the pixel-wise review of mass spectra with our free software RmsiGUI (). This non-proprietary and modular platform enables the cost-efficient adaption of the system and further development by the community.

Strong hydrophilic monolithic column functionalized with amphiphilic benzyl quinine for capillary electrochromatography and application in pharmaceutical analysis.

An innovative strong hydrophilic organic polymer monolithic column of poly(N-benzylquininium chloride-co-1, 3, 5-triacryloylhexahydro-1, 3, 5-triazine) (poly(NBQ-co-TAT)) has been successfully synthesized through in situ copolymerization for capillary electrochromatography. The amphiphilic monomer NBQ and the strong polar cross-linker TAT are firstly used in hydrophilic electrochromatography by taking advantage of the exhibition of hydrophilicity at lower levels of organic solvent and ease formation of porous structure. The monolithic column poly(NBQ-co-TAT) shows powerful hydrophilic selectivity with mobile phase containing more than 60% organic solvent. The introduction of NBQ and TAT enlarges the sources of functional monomers and cross-linkers for HILIC. Due to the presence of the positively charged group in NBQ, an anodic electroosmotic flow is generated with the change of pH values from 2.0 to 12.0. The monolithic column was used for the separations of thioureas, phenols, xanthines, nucleobases, acidic substances and pharmaceuticals. The highest column efficiency for N, N'-dimethylthiourea is 1.15 × 105 N m-1. The application of the monolithic column for a real sample, cytochrome C digestion indicates its great potential in practical application.

LC-MS/MS-based metabolomic analysis of caffeine-degrading fungus Aspergillus sydowii during tea fermentation.

Natural microorganisms involved in solid-state fermentation (SSF) of Pu-erh tea have a significant impact on its chemical components. Aspergillus sydowii is a fungus with a high caffeine-degrading capacity. In this work, A. sydowii was inoculated into sun-dried green tea leaves for SSF. Metabolomic analysis was carried out by using UPLC-QTOF-MS method, and caffeine and related demethylated products were determined by HPLC. The results showed that A. sydowii had a significant (P < 0.05) impact on amino acids, carbohydrates, flavonoids, and caffeine metabolism. Moreover, A. sydowii could promote the production of ketoprofen, baclofen, and tolbutamide. Along with caffeine degradation, theophylline, 3-methylxanthine, 1,7-dimethylxanthine, 1-methylxanthine, and 7-methylxanthine were increased significantly (P < 0.05) during inoculated fermentation, which showed that demethylation was the main pathway of caffeine degradation in A. sydowii secondary metabolism. The absolute quantification analysis showed that caffeine could be demethylated and converted to theophylline and 3-methylxanthine. Particularly, about 93.24% of degraded caffeine was converted to theophylline, 27.92 mg/g of theophylline was produced after fermentation. PRACTICAL APPLICATION: Aspergillus sydowii could cause caffeine degradation in Pu-erh tea solid-state fermentation and produce theophylline through the demethylation route. Using a starter strain to ferment tea leaves offers a more controllable, reproducible, and highly productive alternative for the biosynthesis of theophylline.

Extraction of methyl xanthines and their UHPLC-DAD determination in consumable beverages used in Eastern province of Saudi Arabia.

Coffee and tea are the most widely consumed beverages worldwide. However, the consumer may be unaware of the exact amount of methyl xanthine (MX, i.e. caffeine [C], theobromine [TB] and theophylline [TH]) consumed, as most of the products do not list the proper amounts. This may lead to serious risks including cardiovascular, kidney and stimulant effects. The aim of the study was to determine the MX amount in ready-to-use beverages (coffee and tea) collected from various outlets in the city of Al-Khobar, Saudi Arabia. Forty different samples of espresso, black coffee and red tea were collected. A fast, reliable and efficient UHPLC-DAD method was developed and validated for MX determination. Total lipids were extracted and fractionated in order to determine glycolipids, phospholipids and neutral lipids. The r2 value for the method was 0.980-0.988 in a linearity range of 0.5-200 ppm. The range for MX (C [0.02-2.39 mg/ml], TB [0.00-0.10 mg/ml] and TH [0.00-0.004 mg/ml]) and total lipids was 1-5 g. The amount of glycolipids (3.1 g) was higher among the lipid fractions followed by phospholipids (1.8 g) and neutral lipids (0.25 g). In general, espresso beverages (20-30 ml) contained high amounts of MX whereas black coffee beverages contained high amount of lipids. Most of the beverages expressed C, TB, TH, lipids or their fractions; however, the product with high amounts of MX and lipids at the same time was espresso (brands Chemistry and Wogard). Although the MX and lipid levels in these beverages well below the allowed limits, care must still be taken, especially when using the beverages with high serving volumes (200-250 ml) or coffee prepared via the filter method i.e. black coffee, using a high temperature for a longer time.

Solvent and temperature effect of accelerated solvent extraction (ASE) coupled with ultra-high-pressure liquid chromatography (UHPLC-PDA) for the determination of methyl xanthines in commercial tea and coffee.

BACKGROUND: Methyl xanthines (MX), known for its psychostimulant effect, occurs mostly in tea and coffee samples. However most of the market available products does not mention the proper amount and quality of MX present where, its consumption in high amount may pose health risks. AIM OF THE STUDY: To develop and validate a fast, efficient and reliable method of MX extraction along with a sensitive, rapid and precise method for simultaneous analysis of MX i.e. Theobromine (TB), Theophylline (TH) and Caffeine (C), with application in commercial tea and coffee samples. MATERIALS AND METHODS: Accelerated Solvent Extraction (ASE) was utilized for the first time to extract MX, whereas UHPLC-DAD was applied in order to quantify MX. RESULTS: ASE resulted a high extract yield (940.22 ± 192.28 mg/g) with optimized conditions of temperature (100 °C) and solvent (MeOH). UHPLC-DAD showed retention time (min) of 1.51 (TB), 1.81 (TH), 2.30 (C) with r2 values (0.980-0.988). Average MX (µg/mL) was as; TB (14.73 ± 20.9), TH (32.05 ± 55.5), C (121.87 ± 32.3). The method application in commercial samples showed a high extract yield with MX concentration (mg/g) as; TB (0.13-0.38), TH (0-0.55), C (7.14-11.20). Temperature and solvent variation showed important correlation with samples in terms of extraction yield. CONCLUSION: ASE-UHPLC/DAD revealed a fast and sensitive method of MX extraction, quantification and quality determination in market available tea and coffee samples.

Graphene Oxide: A Smart (Starting) Material for Natural Methylxanthines Adsorption and Detection.

Natural methylxanthines, caffeine, theophylline and theobromine, are widespread biologically active alkaloids in human nutrition, found mainly in beverages (coffee, tea, cocoa, energy drinks, etc.). Their detection is thus of extreme importance, and many studies are devoted to this topic. During the last decade, graphene oxide (GO) and reduced graphene oxide (RGO) gained popularity as constituents of sensors (chemical, electrochemical and biosensors) for methylxanthines. The main advantages of GO and RGO with respect to graphene are the easiness and cheapness of synthesis, the notable higher solubility in polar solvents (water, among others), and the higher reactivity towards these targets (mainly due to - interactions); one of the main disadvantages is the lower electrical conductivity, especially when using them in electrochemical sensors. Nonetheless, their use in sensors is becoming more and more common, with the obtainment of very good results in terms of selectivity and sensitivity (up to 5.4 × 10-10 mol L-1 and 1.8 × 10-9 mol L-1 for caffeine and theophylline, respectively). Moreover, the ability of GO to protect DNA and RNA from enzymatic digestion renders it one of the best candidates for biosensors based on these nucleic acids. This is an up-to-date review of the use of GO and RGO in sensors.

Effects of hydroalcoholic and enzyme-assisted extraction processes on the recovery of catechins and methylxanthines from crude and waste seeds of guarana (Paullinia cupana).

Catechins and methylxanthines are natural molecules in guarana (Paullinia cupana) that are associated with antioxidant and stimulatory effects in the human body. There are few natural sources of these antioxidants. The most popular molecule used in foods and beverages is caffeine, which, most of the time, is derived from synthetic sources. In this work, cold hydroalcoholic (CHM), hot hydroalcoholic (HHM), and aqueous enzymatic maceration (AEM) were applied to crude (CG) and waste guarana seeds (WG) to process these materials into natural added-value products with enhanced levels of catechin, epicatechin, epicatechin gallate, caffeine, theobromine and theophylline. The highest level of catechins and methylxanthines was extracted with HHM. Nevertheless, AEM enhanced the global yield in the extract, probably due to the solubilization of other substances. The maceration procedures applied to guarana contributed to the valorization of this plant crop by providing antioxidant sources with clear applications in food and nonfood industries.

Multivariate analysis of the composition of bioactive in tea of the species Camellia sinensis.

This study deals with the development of a separation and quantification method by high performance liquid chromatography with a diode array detector (HPLC- DAD), for the determination of phenolic acids and methylxanthines in tea (Camellia Sinensis) samples. Six phenolic acids (Gallic, trans-cinnamic, caffeic, ferulic and p-coumaric acids) and two methylxanthines (caffeine, theobromine) were studied, according to the principles of green chemistry, with the goal of comparing teas with different processing level. After development and validation of separation and extraction methods was applied to 11 extracts obtained by infusions of green and black tea samples in commercial areas of the city of Salvador-BA, showing feasible and efficient. Was employed multivariate data analysis and the Tukey test to correlate the chromatographic profile with the different samples. Principal component and analysis and hierarchical cluster analysis were used for the chromatographic analysis, allowing the visualization of two groups, formed by green and black tea samples.

Optimization of an innovative vinylimidazole-based monolithic stationary phase and its use for pressured capillary electrochromatography.

A novel polymer monolith based on the dicationic crosslinker 3,3'-(hexane-1,6-diyl)bis(1-vinylimidazolium) bromide, the monomer 1-vinylimidazole and a ternary porogen mixture (1-propanol, decan-1-ol and water) was developed and optimized for capillary electrochromatography. This aim was accomplished by adjusting the composition of individual constituents in the polymerization mixture and monitored based on several relevant parameters (e.g. pore structure by scanning electron microscopy, generation of electroosmotic flow, or permeability of material). The ultimately selected composition yielded a monolithic phase which excellently resolved six methylxanthines (including caffeine, theobromine and theophylline) in 15 min. Key requirements concerning the utilized buffer were an acidic pH of 3 and the addition of 50% acetonitrile; additionally, a negative voltage (-25 kV) had to be applied during analyses. The proposed separation mechanism was mixed mode, i.e. the combination of electrostatic repulsion and hydrophobic interaction. Monolith fabrication as well as separation efficiency were found to be highly repeatable, the material was mechanically stable and useable for at least 150 injections. Thus the presented stationary phase is definitely a very promising option for CEC.

Pressurized liquid extraction of flavanols and alkaloids from cocoa bean shell using ethanol as solvent.

Cocoa shell (CS) is a co-product of the cocoa industry used mainly as fuel for boilers but with secondary applications as fertilizer and in animal feed. Although it is known that this material is rich in flavanols and alkaloids, to date, a study has not been conducted that has quantitatively identified these compounds in CS. Thus, the aim of this work was to characterize CS in terms of its composition, regarding catechin, epicatechin, procyanidin B2, caffeine and theobromine, and to evaluate the extraction kinetics of the total flavanols using pressurized liquid extraction (PLE) with absolute ethanol. For the determination of the extraction kinetic data, the DMAC method was used, while each compound was quantified using a UPLC-MS/MS analysis. The major compounds found were theobromine and epicatechin (mean values of 9.89 and 3.5 mg/g CS, respectively). PLE proved to be quite effective; the flavanols extraction yield was enhanced by increasing the temperature and extraction time however, high extraction times and temperatures degraded the procyanidins B2. Peleg's model applied to extraction data description provided a reasonable agreement with the experimental results, which allows their application in modeling and optimization of solid-liquid extraction of the total flavanols from cocoa bean shell.

Characterization of secondary metabolites from green cocoa beans using focusing-modulated comprehensive two-dimensional liquid chromatography coupled to tandem mass spectrometry.

Proanthocyanidins as well as other secondary metabolites present in green cocoa beans were studied thanks to a new method involving the use of on-line comprehensive two-dimensional liquid chromatography coupled to tandem mass spectrometry (LC × LC-MS/MS). In order to enhance the performance of previously developed methodologies, the use of different modulation strategies were explored. Focusing modulation clearly allowed the attainment of higher resolving power and peak capacity compared to non-focusing modulation set-ups. Moreover, the use of active modulation by the addition of a make-up flow efficiently helped to compensate for the solvent strength mismatch produced between dimensions. The optimized method was useful to successfully describe the secondary metabolite composition of green cocoa that was characterized by the presence of 30 main compounds, including 3 xanthines, 2 flavan-3-ols and 24 oligomeric procyanidins with a degree of polymerization up to 12. The obtained results showed that the proanthocyanidins found in the cocoa beans were exclusively B-type procyanidins. The existence of (epi)catechin subunits linked to sugar or galloyl moieties was not observed. The developed method produced a good separation of secondary metabolites allowing an improvement with respect to the available methodologies for the analysis of a complex food sample such as cocoa metabolites in terms of speed of analysis, resolution and peak capacity.

Determination of ligand efficiency indices in a group of 7H-purine-2,6-dione derivatives with psychotropic activity using micellar electrokinetic chromatography.

Discovering hit compounds and optimization processes in medicinal chemistry nowadays could be improved by predictive tools, based on the relationship between structure of molecules and lipophilic properties. Lipophilicity of drug candidate can affect both the pharmacokinetic and pharmacodynamics properties, in particular, the ability of a molecule to cross the cell membrane. Among the new methods for determination of the lipophilicity of compounds, micellar electrokinetic chromatography (MEKC) is considered to be an appropriate one for bioactive molecules, as it closely mimics the physiological conditions. In this paper MEKC was used for the estimation of the lipophilicity of 24 derivatives of 8-alkoxy-7H-purine-2,6-dione, designed and synthesized as potential antidepressant/anxiolytic and antipsychotic agents. The results of experimental method were compared with calculated in silico parameters (AlogPs and milogP by Virtual Computational Laboratory website, log PPallas by Pallas 3.1, Mlog P by Marvin, log PChemS by ChemSketch, log PChemDraw by ChemBioUltra) using Principal Component Analysis (PCA) method. Finally, using estimated log P values for selected compounds ligand - lipophilicity efficiency (LLE), per cent efficiency index (PEI), and binding efficiency index (BEI) parameters were calculated. Applied MEKC procedure could be used for selection of potential lead structure in a group of 7H-purine-2,6-dione derivatives.

Green coffee seed residue: A sustainable source of antioxidant compounds.

Oil extraction from green coffee seeds generates residual mass that is discarded by agribusiness and has not been previously studied. Bioactive secondary metabolites in coffee include antioxidant phenolic compounds, such as chlorogenic acids. Coffee seeds also contain caffeine, a pharmaceutically important methylxanthine. Here, we report the chemical profile, antioxidant activity, and cytotoxicity of hydroethanolic extracts of green Coffea arabica L. seed residue. The extracts of the green seeds and the residue have similar chemical profiles, containing the phenolic compounds chlorogenic acid and caffeine. Five monoacyl and three diacyl esters of trans-cinnamic acids and quinic acid were identified by ultra-performance liquid chromatography/electrospray ionization-quadruple time of flight mass spectrometry. The residue extract showed antioxidant potential in DPPH, ABTS, and pyranine assays and low cytotoxicity. Thus, coffee oil residue has great potential for use as a raw material in dietary supplements, cosmetic and pharmaceutical products, or as a source of bioactive compounds.

Ilex paraguariensis: Potential antioxidant on aluminium toxicity, in an experimental model of Alzheimer's disease.

Ilex paraguariensis, yerba mate is a native plant from the southern region of Brazil. Studies showed that yerba mate has an antioxidant potential, which could help to reduce the risk of developing neurodegenerative diseases, as Alzheimer's Disease (AD). It's known that I. paraguariensis grows in acid soils with aluminium (Al), which is bioavailable in these soils. Al has a neurotoxic potential related with the progression of neurological disorders. This study aim was to evaluate the potential of I. paraguariensis in the etiology of AD using strains of Caenorhabditis elegans and the concentration of Al and antioxidants in the yerba mate extract. The results of the I. paraguariensis infusions made at 65°C and at 75° C show that there was no significant difference between both temperatures when preparing the tea infusion in relation to the presence of Al, methylxanthines, phenolic compounds and flavonoids. Additionally, in the case of Al, there was no difference between the extracts prepared at both temperatures. The behavioral parameters of C. elegans were altered after a long-term exposure to both factors: I. paraguariensis extract and Al. Through the antioxidant levels results along with the Al content on the Acetylcholinesterase (AChE) activity it is possible to observe that the acute and chronic exposure to Al and I. paraguariensis leaves extract are very similar to wild-type worms. Moreover, we can observe that the results in both the transgenic strains long-term exposed to I. paraguariensis leaves extract and to the Al concentrations presented an increase in the AChE activity.

Daily Intake of Chlorogenic Acids from Consumption of Maté (Ilex paraguariensis A.St.-Hil.) Traditional Beverages.

The main objective of this study was to investigate the daily intake of chlorogenic acids (CGAs) and methylxanthines by consumers of maté traditional beverages (MTBs), terere and chimarrão (Ilex paraguariensis A.St.-Hill). In the studied population (450 citizens from Toledo, PR, Brazil), 63% consume the chimarrão and 37% terere, with weighted mean daily intakes estimated at 648-2160 and 244-746 mL, respectively. For every 100 mL of beverage consumed, the average amount of total phenol compounds extracted was 673.6 mg for chimarrão and 1184.9 mg for terere. Regarding CGAs composition, caffeoylquinic acids (CQAs) constitute about 38.4% for chimarrão and 55.3% for terere, and dicaffeoylquinic acids (diCQAs) represent 61.6 and 44.7% of the extracted compounds, respectively. The daily intake of phenolic compounds by MTB consumers was estimated for chimarrão (512.5-1708.5 mg/day) and terere (583.0-1779.7 mg/day). These results allow us to conclude that MTBs are important dietary sources of CGAs, mainly CQAs and di-CQAs.

Study of nutritional value of dried tea leaves and infusions of black, green and white teas from Chinese plantations

Background: The processing of tea leaves determines the contents of bioactive ingredients, hence it should be expected that each variety of tea, black, red or green, will represent a different package of compounds of physiological importance. Taste and aroma, as well as price and brand are the main factors impacting consumers' preferences with regard to tea of their choice; on the other hand consumers less frequently pay attention to the chemical composition and nutritional value of tea. Objective: The purpose of the study was assessment of the nutritional value of black, green and white high-quality tea leaf from Chinese plantations based on the chemical composition of the dried leaves as well as minerals and caffeine content in tea infusions. Material and methods: The research material included 18 high-quality loose-leaf teas produced at Chinese plantations, imported to Poland, and purchased in an online store. The analyses included examination of the dried tea leaves for their chemical composition (contents of water, protein, volatile substances and ash) and assessment of selected minerals and caffeine contents in the tea infusions. Results: High-quality Chinese green teas were found with the most valuable composition of minerals, i.e. the highest contents of Zn, Mn, Mg, K, Ca and Al and the highest contents of protein in comparison to the other products. Chinese black teas had the highest contents of total ash and caffeine and white teas were characterized with high content of volatile substances, similar to the black teas, and the highest content of water and the lowest content of total ash. Conclusions: The three types of tea brews examined in the present study, in particular green tea beverages, significantly enhance the organism's mineral balance by providing valuable elements

Community analysis of pigment patterns from 37 microalgae strains reveals new carotenoids and porphyrins characteristic of distinct strains and taxonomic groups.

Phytoplankton, with an estimated 30 000 to 1 000 000 species clustered in 12 phyla, presents a high taxonomic and ecophysiological diversity, reflected by the complex distribution of pigments among the different algal classes. High performance liquid chromatography is the gold standard method for qualitative and quantitative analysis of phytoplankton pigments in seawater and culture samples, but only a few pigments can be used as robust chemotaxonomic markers. A major challenge is thus to identify new ones, characteristic of a strain, species, class or taxon that cannot be currently identified on the basis of its pigment signature. Using an optimized extraction process coupled to a HPLC de-replication strategy, we examined the pigment composition of 37 microalgae strains, representative of the broad taxonomic diversity of marine and freshwater species (excluding cyanobacteria). For each species, the major pigments already described were unambiguously identified. We also observed the presence of several minor unidentified pigments in each chromatogram. The global analysis of pigment compositions revealed a total of 124 pigments, including 98 pigments or derivatives unidentified using the standards. Absorption spectra indicated that 35 corresponded to chlorophyll/porphyrin derivatives, 57 to carotenoids and six to derivatives having both spectral signatures. Sixty-one of these unidentified or new carotenoids and porphyrin derivatives were characteristic of particular strains or species, indicating their possible use as highly specific chemotaxonomic markers capable of identifying one strain out of the 37 selected. We developed a graphical analysis using Gephi software to give a clear representation of pigment communities among the various phytoplankton strains, and to reveal strain-characteristic and shared pigments. This made it possible to reconstruct the taxonomic evolution of microalgae classes, on the basis of the conservation, loss, and/or appearance of pigments.

Variation of theanine, phenolic, and methylxanthine compounds in 21 cultivars of Camellia sinensis harvested in different seasons.

This is the first study to use chemometric methods to differentiate among 21 cultivars of Camellia sinensis from China and between leaves harvested at different times of the year using 30 compounds implicated in the taste and quality of tea. Unique patterns of catechin derivatives were observed among cultivars and across harvest seasons. C. sinensis var. pubilimba (You 510) differed from the cultivars of C. sinensis var. sinensis, with higher levels of theobromine, (+)-catechin, gallocatechin, gallocatechin gallate and theasinensin B, and lower levels of (-)-epicatechin, (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG), respectively. Three cultivars of C. sinensis var. sinensis, Fuyun 7, Qiancha 7 and Zijuan contained significantly more caffeoylquinic acids than others cultivars. A Linear Discriminant Analysis model based on the abundance of 12 compounds was able to discriminate amongst all 21 tea cultivars. Harvest time impacted the abundance of EGC, theanine and afzelechin gallate.