Analysis of phenolic compounds in Cynara scolymus L. and Silybum marianum (L.) Gaertn. by HPLC-DAD-ESI/MS

Cynara scolymus L. (artichoke) and Silybum marianum (L.) Gaertn. (milk thistle) are medicinal plants native to the Mediterranean Basin that belong to the Asteraceae family. The flowers and leaves of milk thistle are used in the treatment of liver, spleen and gallbladder disorders [1] and artichoke leaves are used for their cholagogue, choleretic and choliokinetic actions, and also for treatment of dyspepsia and as antidiabetics [2]. The beneficial properties of medicinal plants can be related to their large diversity of phytochemicals, among which phenolic compounds are outstanding. Thereby, the aim of the present work was to obtain and compare the phenolic profiles of artichoke and milk thistle aqueous (prepared by infusion) and hydromethanolic (maceration in methanol: water 80:20, v/v) extracts, using HPLC-DAD-ESI/MS. The aqueous extract of artichoke presented higher concentration in total phenolic compounds (15.29 mg/g extract) than the hydromethanolic extract (4.37 mg/g) with slight differences between the respective profiles; the major flavonoid found in the aqueous and hydromethanolic extract was luteolin-7-O-glucuronide (5.64 and 0.70 mg/g, respectively), followed by luteolin-7-O-glucoside (2.88 and 0.49 mg/g, respectively). Monocaffeoylquinic acid derivatives were only present in the hydromethanolic extract, being 5-O-caffeoylquinic acid (0.49 mg/g) the most abundant one, while dicaffeoylquinic acid derivatives were mostly identified in the aqueous extract; 1,3-O-dicaffeoylquinic acid was the most abundant one in both extracts (0.90 and 0.37 mg/g in the aqueous and hydromethanolic extract, respectively). Regarding to milk thistle preparations, similar phenolic profiles were observed, with only quantitative differences between them. The aqueous extract revealed a higher phenolic compounds concentration (5.57 mg/g) than the hydromethanolic extract (3.56 mg/g), with apigenin-7-O-glucuronide as the major compound in both preparations (3.14 mg/g in the aqueous extract, and 0.58 mg/g in the hydromethanolic extract). Total flavonoids were higher in the aqueous extract (4.66 mg/g), with apigenin-7-Oglucuronide, luteolin-7-O-glucuronide (1.17 mg/g), and apigenin-O-deoxyhexosylglucuronide (0.36 mg/g) as the main constituents. The phenolic acids found in the hydromethanolic extract (total content 1.65 mg/g), included 5-O-caffeolyquinic and protocatechuic acids (0.56 and 0.44 mg/g, respectively). Besides these phenolic acids, the hydromethanolic extract also revealed high levels of luteolin-7-O-glucuronide (0.58 mg/g). Overall, aqueous extracts presented higher phenolic contents than their hydromethanolic extracts in both species, which could be related with the heat treatment to which infusions were subjected.

Nitrogen vs argon: what is the most effective atmosphere for shelf-life extension of buckler sorrel leaves?

Buckler sorrel (Rumex induratus Boiss. & Reut.) is an underutilized leafy vegetable with peculiar sensory properties and potential as a gourmet food. In the food industry, different packaging methods have been used for shelf-life extension, but it is important to know how the quality of minimally processed vegetable is affected by these treatments. Recently, nitrogen and argon have been used for food packaging. Nitrogen is low soluble in water and other food constituents and does not support the growth of aerobic microbes. In turn, argon is biochemically active and appears to interfere with enzymatic oxygen receptor sites. In this study, modified atmospheres enriched with nitrogen and argon were evaluated for shelf-life extension of buckler sorrel leaves. Wild samples were gathered in Bragança, Portugal, considering local consumers’ sites and criteria. Healthy and undamaged leaves were selected, rinsed in tap water, and a portion was immediately analyzed (non-stored control). The remaining fresh material was packaged in polyethylene bags under nitrogen- and argon-enriched atmospheres and a conventional control atmosphere (air). All packaged samples were stored at 4 ºC for 12 days and then analyzed. The headspace gas composition was monitored during storage. Different quality attributes were evaluated, including visual (colour), nutritional (macronutrients, individual sugars and fatty acids) and bioactive (hydrophilic and lipophilic molecules and antioxidant properties) parameters. Different statistical tools were used; the one-way analysis of variance (ANO VA) was applied for analyse the differences among treatments and a linear discriminant analysis (LDA ) was used to evaluate the effects on the overall postharvest quality. The argon-enriched atmosphere better prevent the samples yellowing. The proximate composition did not change significantly during storage. Samples in control atmosphere revealed higher protein and ash contents and lower levels of lipids. The non-stored control samples presented the higher amounts of fructose, glucose and trehalose. The storage time increased the palmitic acid levels and decreased the content in α-linolenic and linoleic acids. The γ- e δ-tocopherols were higher after the 12 days of cold storage. Probably, the synthesis of these lipophilic compounds was a plant strategy to fight against the abiotic stress induced by storage. Higher levels of total phenolics and flavonoids and increased reducing power and β-carotene bleaching inhibition capacity were also found in the stored control samples. Once again, this result may be attributed to the intrinsic plant-protection mechanisms. Overall, the argon atmosphere was more suitable for quality preservation and shelf-life extension of buckler sorrel.

Information brokers and the use of budgetary and financial information by politicians: the case of Portugal

This paper analyses the intermediary role of the technical bodies that support the use of budgetary and financial information by central government politicians in Portugal. The main findings show that information brokers are playing a central role in preparing this information in a credible, simple and understandable way. However, even if not intentionally, the information they present can be biased. Politicians need to be aware that the information brokers they rely on may not be giving them ‘neutral’ information.