Flavonoid glycosides from endemic bulgarian astragalus aitosensis (Ivanisch.)

© 2019 The Author(s). Background: The activity and haemolytic toxicity associated with primaquine has been linked to its reactive metabolites. The reactive metabolites are thought to be primarily formed through the action of cytochrome P 450 -mediated pathways. Human erythrocytes generally are not considered a significant contributor to drug biotransformation. As erythrocytes are the target of primaquine toxicity, the ability of erythrocytes to mediate the formation of reactive oxidative primaquine metabolites in the absence of hepatic enzymes, was evaluated. Methods: Primaquine and its enantiomers were incubated separately with human red blood cells and haemoglobin. Post-incubation analysis was performed with UPLC-MS/MS to identify products of biotransformation. Results: The major metabolite detected was identified as primaquine-5,6-orthoquinone, reflecting the pathway yielding putative active and haematotoxic metabolites of primaquine, which was formed by oxidative demethylation of 5-hydroxyprimaquine. Incubation of primaquine with haemoglobin in a cell-free system yielded similar results. It appears that the observed biotransformation is due to non-enzymatic processes, perhaps due to reactive oxygen species (ROS) present in erythrocytes or in the haemoglobin incubates. Conclusion: This study presents new evidence that primaquine-5,6-orthoquinone, the metabolite of primaquine reflecting the oxidative biotransformation pathway, is generated in erythrocytes, probably by non-enzymatic means, and may not require transport from the liver or other tissues

ANTIOXIDANT AND GLUCOSIDASE INHIBITION ACTIVITIES AND POLYPHENOL CONTENT OF FIVE SPECIES OF AGRIMONIA GENUS

Phytochemical analysis and a comparative study of antioxidant activity, inhibition of a-glucosidase and content of total polyphenols and flavonoids were established in five species of Agrimonia genus. Plants were collected in Medicinal Herbs Centre of Masaryk university Brno and these were Agrimonia eupatoria L., Agrimonia procera Wallr., Agrimonia leucantha Kunze, Agrimonia japonica (Miq.) Koidz and Agrimonia coreana Nakai. HPLC profile of Agrimonia herbs shows high content of quercetin and apigenin glycosides. The content of total polyphenols correlates with antioxidant activity and the content of flavonoids correlates with inhibition of a-glucosidase. Agrimonia procera works as an excellent antioxidant, the most used in traditional medicine Agrimonia eupatoria is richer on flavonoid glycosides

Anticholinesterase, antioxidant activity and phytochemical investigation into aqueous extracts from five species of <i>Agrimonia</i> genus

<p>Aqueous extracts of aerial flowering parts of five <i>Agrimonia</i> species (Rosaceae): <i>Agrimonia coreana</i> Nakai, <i>Agrimonia japonica</i> (Miq.) Koidz, <i>Agrimonia procera</i> Wallr., <i>Agrimonia eupatoria</i> L. and <i>Agrimonia leucantha</i> Kunze were investigated on their antioxidant activity, measured using five different methods; the best was the extract from <i>A. procera</i> with IC₅₀ values from 6 to 29 μg/mL. All the extracts displayed inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) at the tested concentration of 100 μg/mL. We found the highest inhibition of cholinesterase in the extract of <i>A. japonica</i> with inhibition 70.4% for AChE and 79.8% for BuChE. These findings are statistically significant in comparison with those of other extracts (<i>p</i> < 0.001). The phytochemical analyses showed that the antioxidant activity of <i>Agrimonia</i> extracts can be affected especially by hexahydroxydiphenoyl (HHDP)-glucose and quercetin glycosides, and inhibition of cholinesterases by apigenin, luteolin and quercetin glycosides.</p

Flavonoid Glycosides from Endemic Bulgarian <i>Astragalus aitosensis</i> (Ivanisch.)

Astragalus is a very interesting plant genus, well-known for its content of flavonoids, triterpenes and polysaccharides. Its secondary metabolites are described as biologically active compounds showing several activities, e.g., immunomodulating, antibacterial, antiviral and hepatoprotective. This inspired us to analyze the Bulgarian endemic A. aitosensis (Ivanisch.) to obtain deeper information about its phenolic components. We used extensive chromatographic separation of A. aitosensis extract to obtain seven phenolic compounds (1&#8211;7), which were identified using combined LC-MS and NMR spectral studies. The 1D and 2D NMR analyses and HR-MS allowed us to resolve the structures of known compounds 5&#8211;7 as isorhamnetin-3-O-robinobioside, isorhamnetin-3-O-(2,6-di-O-&#945;-rhamno-pyranosyl-&#946;-galactopyranoside), and alangiflavoside, respectively, and further comparison of these spectral data with available literature helped us with structural analysis of newly described flavonoid glycosides 1&#8211;4. These were described in plant source for the first time

Antioxidant Activity of Selected Stilbenoid Derivatives in a Cellular Model System

The stilbenoids, a group of naturally occurring phenolic compounds, are found in a variety of plants, including some berries that are used as food or for medicinal purposes. They are known to be beneficial for human health as anti-inflammatory, chemopreventive, and antioxidative agents. We have investigated a group of 19 stilbenoid substances in vitro using a cellular model of THP-1 macrophage-like cells and pyocyanin-induced oxidative stress to evaluate their antioxidant or pro-oxidant properties. Then we have determined any effects that they might have on the expression of the enzymes catalase, glutathione peroxidase, and heme oxygenase-1, and their effects on the activation of Nrf2. The experimental results showed that these stilbenoids could affect the formation of reactive oxygen species in a cellular model, producing either an antioxidative or pro-oxidative effect, depending on the structure pinostilbene (2) worked as a pro-oxidant and also decreased expression of catalase in the cell culture. Piceatannol (4) had shown reactive oxygen species (ROS) scavenging activity, whereas isorhapontigenin (18) had a mild direct antioxidant effect and activated Nrf2-antioxidant response element (ARE) system and elevated expression of Nrf2 and catalase. Their effects shown on cells in vitro warrant their further study in vivo