Phenolic constituents of lamium album: focus on isoscutellarein derivatives

Lamium album L. is an edible plant which is consumed raw or cooked, in particular in the Mediterranean and surrounding areas. It is also consumed as tea infusions and as a main component of food supplements, because of its pharmacological effects. Despite being consumed by humans for centuries, the chemical composition of L album L is far from being understood. In this study, a purified ethanolic extract (PEEL) was prepared and further analyzed by high performance liquid chromatography and electrospray mass spectrometry. Overall, verbascoside accounted for approximately half of the phenolic content of the extract, but this also contained other bioactive phenolic compounds herein detected for the first time in the genus, namely isoscutellarein derivatives. The latter included isoscutellarein-7-O-allosyl(1 -> 2)glucoside, its O-methyl derivative, three acetyl derivatives of isoscutellarein-O-allosyl glucoside and one acetylated form of O-methylisoscutellarein-7-O-allosyl(1 -> 2)glucoside. From those, the main isoscutellarein derivative was assigned to isoscutellarein-7-O-(6-O-acetyl-beta-allosyl)(1 -> 2)-beta-glucoside, as confirmed by NMR. Altogether, isoscutellarein derivatives accounted for almost 30% of PEEL phenolics. Since verbascoside and isoscutellarein derivatives are main components of L album L ethanolic extract, their possible association to the health benefits of the plant is discussed

Unusual flavones in cytisus desf.

Cytisus Desf. (Fabaceae) is a diversified genus enclosing approximately sixty species, which are particularly found around the Mediterranean Sea. Many plants of this genus exhibit bioactive properties such as diuretic, hypnotic, anxiolytic, antiparasitic, antidiabetic and antioxidant [1] and, in particular the latter, has been closely associated to the high content in flavonoids [2]. The present work aims to contribute to the knowledge of Cytisus Desf. chemical composition, through the identification of new flavonoids in that genus. The compounds in focus were detected in ethanolic extracts of Cytisus multiflorus flowers by means of HPLC-DAD, ESI-MS and MSn analyses. These included the two isomers 2′′-O-pentosyl-6-C-hexosyl-luteolin and 2′′-O-pentosyl-8-C-hexosyl-luteolin (MW 580 Da), the two isomers 2′′-O-pentosyl-6-C-hexosyl-apigenin and 2′′-O-pentosyl-8-C-hexosyl-apigenin (MW 564 Da), the 6′′-O-(3-hydroxy-3-methylglutaroyl)-2′′-O-pentosyl-C-hexosyl-luteolin (MW 724 Da) and the 6′′-O-(3-hydroxy-3-methylglutaroyl)-2′′-O-pentosyl-C-hexosyl-apigenin (MW 708 Da). Attending that half of the these compounds were herein described for first time in Fabaceae, overall, the present work is a valuable contribution for the phenolic elucidation of Cytisus genus as well as the Fabaceae family

Simultaneous characterization and quantification of phenolic compounds in Thymus x citriodorus using a validated HPLC-UV and ESI- MS combined method

Thymus x citriodorus is a Lamiaceae plant extensively cultivated in Mediterranean region and used for centuries in culinary and in traditional medicine. The present work describes the detailed phenolic composition of T. x citriodorus for the first time, the by means of HPLC-DAD, ESI-MS and MSn and nuclear magnetic resonance (NMR) analyses. The ethanolic extract of T. x citriodorus was analyzed by reversed phase HPLC. The method of analysis was also validated concerning its linearity, instrumental and method precision (for repeatability, immediate precision and intermediate precision) and accuracy (absolute recovery study). The technique was combined with electrospray mass spectrometry in order to identify the phenolic compounds and the structure of the main phenolics was also confirmed by NMR analysis. The in-house validated HPLC-DAD method showed good linearity for the tested reference compounds as well as satisfactory repeatability and immediate precision values, for both instrument and method. Furthermore, the satisfactory results of intermediate precision analysis and recovery assays indicated that the chromatographic method could be used to quantify the main phenolic compounds of T. x citriodorus with adequate precision and accuracy. The extract was rich in rosmarinic acid (10.4±0.6 mg/g extract) that is a widespread phenolic acid in Thymus plants, but also in luteolin-7-O--glucuronide (12±2 mg/g extract), that was herein reported in Thymus for the first time. Other novel compounds comprised one eriodictyol dihexoside with O-glycosidic linkages, two eriodictyol-O-monohexosides, one quercetagetin dimethyl ether-O-hexoside, one naringenin-O-hexoside and chrysoeriol-7-β-O-glucoside. Having in mind the health-promoting properties reported in literature for some of the main polyphenols found in T. x citriodorus, we suggest that this plant has a high potential for being used as a functional food

Characterization of 2,3-diarylxanthones by electrospray mass spectrometry: gas-phase chemistry versus known antioxidant activity properties

Xanthones (XH) are a class of heterocyclic compounds widely distributed in nature that hold numerous noteworthy biological and antioxidant activities. Therefore, it is of utmost importance to achieve relevant detailed structural information to understand and assist prediction of their biological properties. The potential relationship between radical-mediated xanthone chemistry in the gas phase and their promising antioxidant activities has not been previously explored.Thanks are due to Fundação para a Ciência e Tecnologia (FCT, Portugal), European Union, QREN, FEDER and COMPETE, for funding the QOPNA research unit (project PEst-C/QUI/UI0062/2013; FCOMP-01-0124-FEDER-037296), and the Portuguese National Mass Spectrometry Network, RNEM (REDE/1504/REM/2005). E. M. P. Silva is also grateful to FCT (ref SFRH/BPD/66961/2009) for a Post-Doc grant.info:eu-repo/semantics/publishedVersio

The origin of pinking phenomena in white wines: An update

Pinking is the term used to describe the appearance of a salmon-red blush color that may appear in bottled white wines, produced solely from white grape varieties. It is perceived as an undesirable phenomenon for both, wine consumers and winemakers. Although with seasonal and regional variations, the pinking has been observed worldwide, with predominance in white wines produced from Vitis vinifera L. grape varieties. The pinking origin of Síria white grapes has been studied in detail and it has been shown that the origin of the pinking phenomenon in white wines from Vitis vinifera L. Síria grape variety are anthocyanins, mainly malvidin-3-O-glucoside. The minimum amount of anthocyanins needed for the visualization of the wine pink color was 0.3 mg/L. Further studies in other white monovarietal wines that occasionally suffer from this defect, like white wine from Malvasia Fina grape variety, Loureiro grape variety, Sauvignon Blanc grape variety and Albariño grape variety, have shown that this wines produced from this grape varieties also show low amounts of anthocyanins, mainly malvidin-3-O-glucoside. These results show that the presence of low but visible detectable anthocyanins as the origin of the pinking phenomena is also observed in other white grape varieties besides that of Síria