Adenosine is a potent endogenous regulator of inflammation and tissue repair. Adenosine, which is released from injured and hypoxic tissue or in response to toxins and medications, may induce ...pulmonary fibrosis in mice, presumably
via
interaction with a specific adenosine receptor. We therefore determined whether adenosine and its receptors contribute to the pathogenesis of hepatic fibrosis.
As in other tissues and cell types, adenosine is released
in vitro
in response to the fibrogenic stimuli ethanol (40 mg dl
−1
) and methotrexate (100 n
M
).
Adenosine A
2A
receptors are expressed on rat and human hepatic stellate cell lines and adenosine A
2A
receptor occupancy promotes collagen production by these cells. Liver sections from mice treated with the hepatotoxins carbon tetrachloride (CCl
4
) (0.05 ml in oil, 50 : 50 v : v, subcutaneously) and thioacetamide (100 mg kg
−1
in PBS, intraperitoneally) released more adenosine than those from untreated mice when cultured
ex vivo
.
Adenosine A
2A
receptor‐deficient, but not wild‐type or A
3
receptor‐deficient, mice are protected from development of hepatic fibrosis following CCl
4
or thioacetamide exposure.
Similarly, caffeine (50 mg kg
−1
day
−1
, po), a nonselective adenosine receptor antagonist, and ZM241385 (25 mg kg
−1
bid), a more selective antagonist of the adenosine A
2A
receptor, diminished hepatic fibrosis in wild‐type mice exposed to either CCl
4
or thioacetamide.
These results demonstrate that hepatic adenosine A
2A
receptors play an active role in the pathogenesis of hepatic fibrosis, and suggest a novel therapeutic target in the treatment and prevention of hepatic cirrhosis.
British Journal of Pharmacology
(2006)
148
, 1144–1155. doi:
10.1038/sj.bjp.0706812
Alkalization is an important process in cocoa powder production that affects color and flavor. In this study, the impact of alkalization temperature (60, 70, 80, 90, 100 °C), NaOH concentration ...(0.59, 1.17, 2.34, 3.59% w/w of cocoa powder) and alkalization time (1 and 10 min) on the physicochemical properties (pH, color) and phytochemical profile (theobromine, caffeine, epicatechin, catechin) of cocoa powder were investigated, while the aroma was studied on the corresponding cocoa drinks. High-performance liquid chromatography coupled to an ultra-violet detector (HPLC-UV) was used for screening the non-volatiles and headspace solid - phase microextraction - gas chromatography - mass spectrometry (HS-SPME-GC-MS) for the aromatic compounds. Major changes of the cocoa properties occurred during the first minute of alkalization. Increase of temperature and alkali concentration generally reduced the levels of epicatechin and the lightness (L*), while the pH of the cocoa powder was affected by changing the alkali concentration. On the other hand, the reddish (a*) and yellowish (b*) color component values and theobromine levels were not significantly affected by varying temperature and alkali concentration. A higher temperature did not affect the concentration of the volatile compounds, while a decrease in certain chemical classes was observed by increasing the alkali concentration.
•Cocoa powder alkalization is a rapid reaction but difficult to be controlled.•Most changes on pH, color and caffeine occur during the first min of alkalization.•High alkali concentrations have a negative effect on phytochemical content.•Volatiles change mainly when varying the alkali concentration than temperature.•Harsher temperatures or alkalization prior roasting could affect the volatiles.
Variation in methylxanthines (theobromine and caffeine) and flavanols (catechin and epicatechin) was studied in a large set of cocoa powders (covering different origins, processing parameters and ...alkalisation levels). The content of these compounds was established by high-performance liquid chromatography (HPLC), whose results showed that the alkalisation process lowered the content of all analytes, whose loss was more evident in flavanols. Therefore, the determination of these analytes in a huge set of samples allowed not only better knowledge of the concentration variability in natural commercial cocoas from different origins, but also the understanding of the effect that industrial alkalisation has on these contents. The feasibility of reflectance near-infrared spectroscopy (NIRS) combined with partial least square (PLS) to non-destructively predict these contents, was also evaluated. All the analytes were generally well predicted, with predictions for methylxanthines (R2P 0.819–0.813 and RMSEP 0.068–0.022%, and bias 0.005 and 0.007 for theobromine and caffeine, respectively) and for flavanols (R2P 0.830–0.824; RMSEP 8.160–7.430% and bias −1.440 and −1.034 for catechin and epicatechin, respectively). Thus NIRS could be an alternative fast reliable method for the routine assessment of these analytes in the cocoa industry.
•Methylxanthine and flavanol contents in cocoa powders were established by HPLC.•The alkalisation process of cocoa powders reduced all analyte content.•Methylxanthine and flavanol contents were predicted by NIRS and PLS.•All analytes were well-predicted by PLS, especially methylxanthines.
The high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD) was optimized for the simultaneous determination of 11 compounds, belonging to polyphenols (gallic acid and ...seven catechins) and methylxanthines (caffeine, theobromine, and theophylline). The results obtained for all the validation parameters of the HPLC-DAD method showed that the method is sensitive enough for routine analysis with basic chromatographic equipment, thus it has a significant potential to be highly applicable in common laboratory practice. The method was used in the analysis of 60 green tea infusions originating from four tea-producing countries. The dataset contributes to enhancing current data on green tea. The analysis of green tea extracts revealed significant differences depending on the origin of the samples. Linear Discriminant Analysis (LDA) was applied to test the accuracy of identification of the origin of the tea samples, based on the chemical composition of tea with a focus on polyphenolic compounds and methylxanthines analysed in this study. Based on cross-validation results, the model showed 93.75 % accuracy in the classification of green tea originating from Japan, China (Mainland), China (Taiwan) and South Korea.
•The new HPLC method for 8 tea polyphenols and 3 methylxanthines determination.•The method validation and evaluation of its applicability for the routine use.•The method application on the analysis of 60 green tea samples from four regions.•The LDA model for green tea classification based on chemical composition.
The present work pursued the development of a system to detect and quantify methylxanthines in Ilex guayusa. The system, called IPMA (In situ Plant Metabolite Aptasensor), is based on an optical ...aptasensor that integrates a DNA complex and a porphyrin (NMM IX). IPMA's ability to detect known amounts of theophylline and caffeine in solution and infiltrated in guayusa's leaves was evaluated. The detection limits determined were: 0.25 mM for theophylline in solution, 0.1 mM for caffeine in solution, and 130 mM for caffeine in I. guayusa leaves. These results demonstrate the potential of IPMA to detect and quantify metabolites of interest directly from biological samples. Developing this type of tool will provide a wide range of applications such as the in situ determination of physiological stress in plants and the characterization of plant varieties with a higher content of compounds of pharmaceutical or food interest.
The concentrations of theobromine (TB) and caffeine (CF) together with other substances such as phenolic compounds, contribute to the perception of the bitter taste characteristic of fermented and ...unfermented Amazonian cocoa samples and their edible derivatives, such as chocolates. Thus, an analytical method based on square wave voltammetry (SWV) with a boron doped diamond electrode (BDD) was proposed to determine them. The supporting electrolyte, pH buffer solutions and parameters of the SWV technique were studied, and after determining the optimal conditions, analytical curves were constructed and the limits of detection and quantification calculated as 0.027 μmol L−1 and 0.093 μmol L−1 for CF and 0.025 and 0.085 μmol L−1 for TB. Intra-day and inter-day repeatability tests were carried out and the relative standard deviation values were below 2.51% and 6.50%, respectively. Interference studies were carried out and no potential interferents were found, except for high levels of TB in the presence of low CF concentrations, and vice-versa. To overcome this drawback, a preparative chromatographic procedure was used and the isolated aliquots of TB and CF quantified using SWV and high performance liquid chromatography (HPLC) with photodiode array detectors (PAD) as the reference method. Due to the low concentration of CF in the Amazonian cocoa sample, a miniaturized electrochemical cell produced in a 3D printer was developed. Based on the results, the relative errors were lower than 10% and the critical values for the F and t tests were lower than those tabulated at the 95% confidence level, with n = 3. The recoveries ranged from 80% to 115%. According to the results one can determine the TB and CF contents with acceptable precision and accuracy in fermented and unfermented Amazonian cocoa samples with a reduced amount of residues, representing good analytical tools for the quality control of fermented cocoa and chocolate.
•The first time an electrochemical analysis of theobromine and caffeine was carried out after chromatographic separation.•Application in a fermentation process step monitoring levels of methylxanthines, especially caffeine and theobromine.•The electrochemical detection was precise, fast, economical and environmental-friendly.
The use of zero-waste processes to integrate food-waste valorisation into the circular economy equation is currently one of the hottest topics in sustainability research. This goal is still far from ...being fully achieved despite the release of a number of patents and papers that deal with the topic.
The present work aims to valorise cocoa shells, one of the main by-product of the roasting process, in order to enhance the effective extraction of high added value compounds by means of green protocols. The high potential added value of the residual waste has been demonstrated via a direct analytical comparison of extracts and bean composition.
A range of raw matrix extraction procedures have been investigated in order to define the best solvent and technology; ultrasound (US) and hydrodynamic cavitation (HC) were compared with conventional methods. The high-energy microenvironments generated by cavitation substantially promote fast biomass deconstruction with low energy consumption. The optimized protocol couples a HC reactor with a ternary water/ethanol/hexane mixture, simultaneously providing a hydrophilic product, which is rich in methylxanthines and polyphenols, and a lipid layer.
Sequential milling and sieving pretreatment provided an enriched shell fraction via the partial removal of husk fibres (54.45 vs. 81.36 w/w % total fibres). The disposal of the latter reduces mass balance, but is rerouted into animal feedstock components and crop mulching.
The protocols herein reported produce valuable extracts, which are rich in antioxidant flavanols (catechins and epicatechins), theobromine (32.7 ± 0.12 mg/g shells), caffeine (1.76 ± 0.08 mg/g shells) and cocoa butter, in a simple and easy manner. This new valorisation process afforded 20.5 w/w % and 15.8 w/w % hydrophilic and lipophilic fractions, respectively, when scaled up to function in a pilot flow reactor. The fatty acids, obtained in remarkable yield (forming the 96.4 w/w % of the total light part) well match the commercial cocoa butter profile. The antioxidant extract shows an impressive total phenolic content of 197.4 mg/g extract (gallic acid eq.), with a radical scavenging activity of 62.0 ± 3.1 μg/mL (expressed in DPPH EC50). This work should facilitate industrial design for the convenient recovery of cocoa by-products as part of a zero-waste strategy.
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•Physical separation and selective green extraction enabled the valorisation of cocoa shell waste.•Semi-continuous processes with pilot scale cavitational reactors promote cocoa shell efficient extraction.•The high added value of cocoa shell extract has been demonstrated by direct analytical comparison with bean composition.•A ternary water/ethanol/hexane mixture provides 15.8% w/w in cocoa butter and around 20.5% w/w in hydrophilic compounds.•A scalable protocol for cocoa shell valorisation has been designed aiming to a zero-waste industrial production.
The aims of the current work were to study the influence of geographical areas on polyphenol and methylxanthine contents and the antioxidant activity in cocoa beans from different cocoa-growing areas ...of Colombia, and to evaluate the possibility of establishing a classification based on the geographical areas of the cocoa-growing regions. Eighteen cocoa farms located in eleven cocoa-growing areas were analyzed. The statistical analysis showed significant differences (p<0.05) in total polyphenol content (TPC), flavan-3-ol, epicatechin, catechin, caffeine and theobromine contents as well as the theobromine/caffeine ratio and the antioxidant capacity between some of the different sampled farms, showing a significant effect of the cocoa-producing region on these parameters. Generally, a proportional relationship has been proposed to exist between the polyphenol content with changes in altitude of plant crops, despite this, our results suggest that the lower the altitude, the more polyphenols, flavan-3-ols and epicatechin are produced by the cocoa plant. Results of the principal component analysis (PCA) indicate that caffeine content and the theobromine/caffeine ratio could serve as parameters to establish a cocoa bean classification according to the geographical area of the cocoa-growing regions.
•Simultaneous quantification of catechins and methylxanthines by HPLC was performed.•The content of cocoa bioactives notably differed among the sampled cocoa farms.•Multivariate analysis showed two main clusters depending on cocoa-growing areas.
•Fifty-eight phenolic compounds and two methylxanthines were identified in yerba mate.•Caffeoyl-2,7-anhydro-3-deoxy-2-octulopyranosonic acid isomers are identified for the first time.•First ...identification of 4-sinapoylquinic and other cinnamoylquinic and shikimic acids in mate.•Hydroxycinnamic acid derivatives and flavonols comprise 90% and 10% of mate phenols, respectively.•The antioxidant capacity of mate is mainly associated to its polyphenol content.
Yerba mate is a beverage rich in bioactive compounds popular in South America. Polyphenols and methylxanthines were qualitatively and quantitatively analyzed in four commercial brands of yerba mate, as well as the antioxidant capacity of the beverages. Using LC/MSn analysis, 58 polyphenols were observed of which 4-sinapoylquinic acid, di- and tri-methoxycinnamoylquinic acids, two isomers of trimethoxycinnamoylshikimic acid and four isomers of caffeoyl-2,7-anhydro-3-deoxy-2-octulopyranosonic acid were identified for the first time in mate. Additionally, 46 polyphenols and 2 methylxanthines were quantified by HPLC-DAD. Hydroxycinnamic acid derivatives and flavonols comprised 90% and 10% of mate phenols, respectively, 3-caffeoylquinic (26.8–28.8%), 5-caffeoylquinic (21.1–22.4%), 4-caffeoylquinic (12.6–14.2%) and 3,5-dicaffeoylquinic acids (9.5–11.3%) along with rutin (7.1–7.8%) were the most abundant polyphenols, whereas caffeine was the main methylxanthine (90%). Ilex paraguariensis is an important source of polyphenols with moderate methylxanthines content; therefore its high antioxidant capacity was mainly associated to its polyphenolic composition.