1,969 research outputs found

    Critical solution for a Hill's type problem

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    Phenolic composition and antioxidant capacity of cultivated artichoke, Madeira cardoon and artichoke‐based dietary supplements

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    Cynara cardunculus var. scolymus (artichoke) and Cynara cardunculus var. ferocissima (Madeira cardoon) are two Asteraceae plants used in Madeira Archipelago in diet and also for medicinal issues. The present work aimed to compare the phenolic composition and quantify the main compounds of these two plants and two artichoke based dietary supplements (juice and dragées). The methanolic extract of the endemic plant cardoon was basi cally composed of caffeoylquinic acid isomers. The same compounds were observed in artichoke extract, where there was a larger number and variety of other phenolic compounds. Variations in qualitative and quantitative composition of the three artichoke based products were extensive, with only 3 components being common to all 3 products. Mono-O-diglycosilated flavonoids (luteolin, apigenin and quercetin) were found in the artichoke products but not in Madeira cardoon. 1,3-O-dicaffeoylquinic acid (cynarin), usually considered mainly responsi ble for the biological properties of artichoke, was found in high amounts ranging in most samples but was not detected in the analyzed commercial dragées. The antioxidant assays results reflected the highly diversified com position of the artichoke-based products, showing a high radical scavenger and reducing capacities, while the ex tract from Madeira cardoon was a poor antioxidantinfo:eu-repo/semantics/publishedVersio

    Validation of a HPLC-DAD–ESI/MSn method for caffeoylquinic acids separation, quantification and identification in medicinal Helichrysum species from Macaronesia

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    The caffeoylquinic acids (CQA) found in Helichrysum species from Madeira Archipelago were identified and quantified. The HPLC-DAD–ESI/MSn method applied was developed and validated showing a good repeatability with recovery values ≄96%. The use of a RP-C18 with a small internal diameter (Ø 3.0 mm) and an acidic mobile phase (acetonitrile and water with 0.1% (v/v) of formic acid) enabled the separation of all compounds within a 30 min analysis. A good resolution between 1,5-O-diCQA and 3,5-O-diCQA isomers, usually hard to separate, was also accomplished. Dicaffeoylquinic acids isomers were the major components among the quantified hydroxycinnamic acids. 1,5-O-diCQA, 3,5-O-diCQA and 5-O-CQA were the compounds found in higher amounts for the different species. The distinct uses of these plants described in the local folk medicine can be related to the phenolic composition.info:eu-repo/semantics/publishedVersio

    Madeira moneywort (Sibthorpia peregrina L.) as a new source of verbascoside and its derivatives with potential phyto-pharmaceutical applications

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    The qualitative and quantitative characterization of Madeira moneywort (Sibthorpia peregrina L.) compounds was investigated for the first time. The antioxidant activity and the effect of the methanolic extract on digestive enzymes activity linked to type-2 diabetes and obesity were also determined by in vitro assays. A total of 56 components were characterized in S. peregrina. Phenylethanoids glycosides (PhEGs) represented the main classes of compounds (95.23 mg g-1 of dry extract), almost all verbascoside and its derivatives (up to 98.85% of the total individual phenolic content). The analysed sample was active against ABTS, DPPH, nitric oxide and superoxide radicals, suggesting a potential beneficial effect against oxidative stress. In addition, the methanolic extract was able to inhibit the catalytic activity of α-, ÎČ-glucosidases, α-amylase and pancreatic lipase. Overall, S. peregrina showed good perspectives to be explored as a rich source of verbascoside and its derivatives for nutraceutical/pharmaceutical products.This work was supported by Fundação para a CiĂȘncia e a Tecnologia (FCT, Portugal) [grant number SFRH/ BD/84672/2012] with funds from the Portuguese Government (Project PEst-OE/QUI/UI0674/2013) and the Portuguese National Mass Spectrometry Network (Contract RNEMREDE/1508/REM/2005). Funding through the project M1420-01-0145-FEDER-000005 – Centro de QuĂ­mica da Madeira – CQM+(Madeira 14-20).info:eu-repo/semantics/publishedVersio

    Characterisation of phenolic acid derivatives and flavonoids from different morphological parts of Helichrysum obconicum by a RP-HPLC–DAD-(−)–ESI-MSn method

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    The phenolic composition from different morphological parts of Helichrysum obconicum was investigated for the first time and 50 different phenolic compounds were detected. Phenolic acid conjugates, mainly mono- and di-caffeoylquinic acid derivatives, were the major components; some flavonoid derivatives were also detected in small amounts. Their separation and identification was performed by a high-performance liquid chromatography/electron spray ionisation tandem ion trap mass spectrometry method, with special emphasis on MSn fragmentation. The presence of di- and tricaffeoylshikimic acid isomers in Helichrysum species extracts was reported for the first time, the spectra of these compounds were mainly characterised by the presence of a [caffeoylshikimic acid-H]- ion at m/z 335. A lamiridosins-di-O-hexoside, an unusual component in Asteraceae species, was also detected.info:eu-repo/semantics/publishedVersio

    Evaluation of Asteraceae herbal extracts in the management of diabetes and obesity. Contribution of caffeoylquinic acids on the inhibition of digestive enzymes activity and formation of advanced glycation end-products (in vitro)

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    The study was performed to assess, for the first time, the in vitro anti-diabetic potential of ten Asteraceae plant extracts to inhibit the activity of digestive enzymes (α-amylase, α-, ÎČ-glucosidases and lipase) responsible for hydrolysis/digestion of sugar and lipids. Prevention of advanced glycation end-products (AGEs) formation was evaluated in bovine serum albumin/ribose glycation reaction model. The phytochemical profiles and caffeoylquinic acids (CQAs) contents were determined for the methanolic extract of each plant. Analyzed plant extracts exhibited significant inhibitory activity against key digestive enzymes linked to type II diabetes and obesity. A strong inhibition was observed for glucosidases and mild activity towards amylase and lipase (compared to reference compounds). Moreover, some extracts exhibited potent ability to prevent formation of AGEs, implicated in some diabetic complications. Caffeoylquinic acids were dominant in all plant extracts and findings demonstrate that these compounds are the most relevant hypoglycemic and anti-glycation agents. From the obtained results, Argyranthemum pinnatifidum, Helichrysum melaleucum, and Phagnalon lowei are good candidates for further development of phyto-pharmaceutical preparations as complementary therapy for diabetes and obesity control.The authors are grateful to Francisco Fernandes and Jose Carvalho from Madeira Botanical Garden and to Funchal Ecological Park for the supply and identification of plant material.info:eu-repo/semantics/publishedVersio
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