Characterization of enzyme-catalysed endogenous β-hydroxylation of phenylethanoid glycosides in Euphrasia rostkoviana Hayne at the molecular level

Tissue-Specific Accumulation and Isomerization of Valuable Phenylethanoid Glycosides from Plantago and Forsythia Plants

A comparative phytochemical study on the phenylethanoid glycoside (PhEG) composition of the underground organs of three Plantago species (P. lanceolata, P. major, and P. media) and that of the fruit wall and seed parts of Forsythia suspensa and F. europaea fruits was performed. The leaves of these Forsythia species and six cultivars of the hybrid F. × intermedia were also analyzed, demonstrating the tissue-specific accumulation and decomposition of PhEGs. Our analyses confirmed the significance of selected tissues as new and abundant sources of these valuable natural compounds. The optimized heat treatment of tissues containing high amounts of the PhEG plantamajoside (PM) or forsythoside A (FA), which was performed in distilled water, resulted in their characteristic isomerizations. In addition to PM and FA, high amounts of the isomerization products could also be isolated after heat treatment. The isomerization mechanisms were elucidated by molecular modeling, and the structures of PhEGs were identified by nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectrometry (HR-MS) techniques, also confirming the possibility of discriminating regioisomeric PhEGs by tandem MS. The PhEGs showed no cytostatic activity in non-human primate Vero E6 cells, supporting their safe use as natural medicines and allowing their antiviral potency to be tested.

Phytochemical and Bioactive Properties of Phelypaea Tournefortii – Effect of Parasitic Lifestyle and Environmental Factors

Some holoparasitic species can become cultivated plants due to their unique chemical composition. A lot of bioactive contents are characteristic for them. Holoparasites of the family Orobanchaceae are known to be an important and rich source of polyphenols, especially metabolites of the phenylethanoid glycosides (PhGs) group. However, only a minority of the species in this family have been phytochemically tested. They are reported to have multiple biological and therapeutic effects and have been used for centuries in traditional Chinese medicine. This is the first study to present phytochemical profiling for a representative of genus Phelypaea. The chemical composition and biological activity in particular organs of the parasite, P. tournefortii, were determined. The interaction with its host, Tanacetum polycephalum (Asteraceae), from different places and altitudes was also studied. We presented the determination of polyphenolic compounds with the UPLC-PDA-MS/MS method, antioxidative effects and inhibitory activities, polyphenols, and nitrates content, ABTS•+, DPPH, FRAP, as well as colour parameters. The polyphenols profile of the parasite and host were different in quality and quantity. Identification of polyphenolic compounds revealed 41 compounds, 15 in the parasite (12 phenylethanoids and 3 anthocyanins), and 26 in the host (mainly flavonoids and phenolic acids). The amount and biological activity of polyphenolic compounds present in Phelypaea was very diverse and depended on the host plant and the parasite’s organs, as well as on population altitude. The results show that P. tournefortii is a potential source of functional and pro-health components. They also direct researchers’ attention to the parasite’s organs, host, and environmental influence.

Characterization of antioxidant phenolics in Syringa vulgaris L. flowers and fruits by HPLC-DAD-ESI-MS

In this study the polyphenolic composition of lilac flowers and fruits was determined for the first time. For the identification of compounds, accurate molecular masses and formulas, acquired by LC and ESI-TOF-MS and fragmentation pattern given by LC-ESI/MS/MS analyses, were used. Our chromatographic system in conjunction with tandem MS was found to be valuable in the rapid separation and determination of the multiple constituents in methanolic extracts of lilac flowers and fruits. Altogether 34 phenolics, comprising 18 secoiridoids, seven phenylpropanoids, four flavonoids and five low-molecular-weight phenols, were identified. As marker compounds two secoiridoids (oleuropein and nuzhenide), two phenylpropanoids (acteoside and echinacoside) and rutin were quantified by validated methods. As a result of quantitative analysis, it was confirmed that flowers contain significant amounts of phenylpropanoids (acteoside, 2.48%; echinacoside, 0.75%) and oleuropein (0.95%), while in fruits secoiridoid oleuropein (1.09%) and nuzhenide (0.42%) are the major secondary metabolites. The radical scavenging activities of the extracts and the constituents were investigated by DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS [2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)] assays. Both extracts show remarkable antioxidant activities. Our results clearly show that lilac flowers and fruits are inexpensive, readily available natural sources of phenolic compounds with pharmacological and cosmetic applications. Copyright © 2015 John Wiley & Sons, Ltd.