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Extremely Rare Flavonoid Glycosides Identified in the Stems of Ephedra gerardiana by HPLC-MS and Their Antioxidant Activity
The plants of the genus Ephedra are mainly known for the contents of alkaloids; however, it has recently been found that they also contain phenolic constituents that show interesting bioactivities, e.g., antioxidative or antimicrobial. From among the Ephedrae herba, the Ephedra gerardiana seems to be relatively poorly researched in terms of flavonoid presence. In this study, on the basis of the results of high-pressure liquid chromatography–mass spectrometry (HPLC-MS) with cone voltage-induced fragmentation analysis, which are discussed in detail, the flavonoid glycosides present in Ephedra gerardiana have been identified. Besides the flavonoids typical of the genus Ephedra, e.g., afzelin, herbacetin 7-O-glucoside, and vicenin-2, compounds that are very rare in nature have been detected as well, namely the p-coumaroyl conjugates of 4′-O-methylafzelin and malonyl flavone C-glycosides. Therefore, Ephedra gerardiana can be regarded as a valuable source of these compounds. Furthermore, the antioxidant activity of the methanol extract indicates that these compounds show potential interesting biological activities.
Structure elucidation of quercetin- and myricetin-O‐glycosides from the seeds of Trifolium repens
Post-Column Guanosine Addition as a Screening Tool in the Search for Effective G-Quadruplex Binders - A Case Study of Achyrocline satureioides Phenolic Compounds
Polyphenols make a numerous and diverse group of plant secondary metabolites exhibiting remarkable anticancer activities, often attributed to their G-quadruplex binding properties. Therefore, there is a need to develop a high–throughput screening assay which would permit the evaluation of polyphenols’ binding properties toward G-quadruplex. As deoxyguanosine and guanosine are essential and key building blocks of G-quadruplexes, the stabilities of their adducts with polyphenols may reflect the stabilities of polyphenols–G-quadruplex adducts. In this study, deoxyguanosine/guanosine post-column addition experiments have been performed during HPLC-MS analysis of Achyrocline satureioides extract. The stabilities of the deoxyguanosine/guanosine adducts with 3-O-methylquercetin-7-O-glucoside, 4′-hydroxydehydrokawain-4′-O-glucoside, and 3,5-di-O-caffeoylquinic acid—compounds identified in the Achyrocline satureioides extract—have been tested by using collision-induced dissociation ‘in-source’. The obtained results show that the identified compounds form more stable adducts with deoxyguanosine and guanosine than the standards used for comparison, namely isoquercitrin and rutin. The performed molecular docking provided some insight into the structure of the adducts and revealed that multiple interactions are of key importance for their stabilities.
Seasonal Qualitative Variations of Phenolic Content in the Stem Bark of Prunus persica var. nucipersica - Implication for the Use of the Bark as a Source of Bioactive Compounds
Abstract The seasonal variations of the phenolic content in the stem bark of Prunus persica var. nucipersica were analyzed by using high pressure liquid chromatography/electrospray ionization mass spectrometry. Great differences were observed for flavanone 5‐O‐glycosides, rutin and acetylated p ‐coumaroylsucrose conjugates containing 0–4 acetyl groups. It is a matter of discussion in which period of the year, May‐August or September‐April, the bark of Prunus persica is the most valuable source of bioactive constituent. If the presence of rutin is desirable, May‐August is the appropriate harvest period, whereas September‐April is appropriate if the presence of flavanone 5‐O‐glycosides is of interest.
HPLC-MS Identification of the Most Abundant Flavonoid Glycosides in the Pods of Abelmoschus esculentus – Comments on the Published Data
Extraction with Acidified Methanol - An Easy and Effective Method of Methyl Chlorogenate Formation, as Studied by ESI-MS
Among the different Hawthorn species, Crataegus monogyna seems to be one of the most often used in herbal medicine, and is commercially available. The methanolic extract and the acidified methanol extract of an herbal medicinal product based on Crataegus monogyna inflorescences were analyzed by using high-pressure liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS). On the basis of m/z of [M-H]− ions and characteristic fragmentation patterns, a number of polyphenolic compounds, namely flavonoids and chlorogenic acids, were identified. It was found that the contents of the acid extract were enriched with methyl chlorogenates showing attractive biochemical properties. Analogous results were obtained for other plant materials, e.g., nectarine kernels. Apart from that, acid extraction had a minor influence on the polyphenolic compounds present in the plants, and thus it did not affect the natural antioxidant values of the plant extracts.
Oligoester Identification in the Inner Coatings of Metallic Cans by High-Pressure Liquid Chromatography–Mass Spectrometry with Cone Voltage-Induced Fragmentation
The application of polyesters as food contact materials is an alternative to epoxy resin coatings, which can be a source of endocrine migrants. By using high-pressure liquid chromatography/electrospray ionization–mass spectrometry (HPLC/ESI-MS) with cone voltage-induced fragmentation in-source, a number of polyester-derived migrants were detected in the extracts of inner coatings of metallic cans. The polyester-derived migrants were detected in each inner coating of fish product-containing cans (5/5) and in one inner coating of meat product-containing can (1/5). They were not detected in the inner coatings of vegetable/fruit product-containing cans (10 samples). The respective detected parent and product ions enabled differentiation between cyclic and linear compounds, as well as unambiguous identification of diol and diacid units. Most of the detected compounds, cyclic and linear, were composed of neopentyl glycol as diol and two diacid comonomers, namely isophthalic acid and hexahydrophthalic acid. The other detected oligoesters were composed of neopentyl glycol or propylene glycol and adipic acid/isophthalic acid as comonomers. The compounds containing propylene glycol as diol were found to be exclusively linear cooligoesters. On the basis of abundances of [M+Na]+ ions, the relative contents of cyclic and linear oligoesters were evaluated.
HPLC-MS Detection of Nonylphenol Ethoxylates and Lauryl Ethoxylates in Foodstuffs and the Inner Coatings of High-Barrier Pouches
The widespread use of non-ionic surfactants, e.g., nonylphenol ethoxylates or dodecyl ethoxylates, may result in their occurrence in foodstuffs. In this paper, extracts from the coatings and from the contents of high-barrier food pouches were analyzed by high-pressure liquid chromatography–mass spectrometry. These flexible pouches are an alternative package format of growing interest which can replace traditional cans. In almost all samples, nonylphenol ethoxylates and dodecyl ethoxylates were detected. The identified nonylphenol ethoxylates usually contained 4–10 oxyethylene units, while the identified dodecyl ethoxylates contained 3–13 oxyethylene units. However, in a few samples, longer fractions of dodecyl ethoxylates were detected, namely those containing >15 oxyethylene units. A comparison of the non-ionic surfactant concentrations in the coating extracts with their concentrations in the content extracts indicated that the coating materials were not the main sources of the contents’ contamination. Other contaminants, namely BADGE conjugates and cyclic cooligoesters, which are common contaminants of canned foodstuffs, were found to rarely occur in high-barrier food pouches. Unexpectedly, in one sample polypropylene glycol was detected at a low concentration; this compound has not been previously identified as a potential food contaminant.