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Various phytochemicals have been reported to protect against oxidative stress. However, the mechanism underlying has not been systematically evaluated, which limited their application in disease treatment. Nuclear factor erythroid 2-related factor 2 (Nrf2), a central transcription factor in oxidative stress response related to numerous diseases, is activated after dissociating from the cytoskeleton-anchored Kelch-like ECH-associated protein 1 (Keap1). The Keap1-Nrf2 protein-protein interaction has become an important drug target. This study was designed to clarify whether antioxidantive phytochemicals inhibit the Keap1-Nrf2 protein-protein interaction and activate the Nrf2-ARE signaling pathway efficiently. Molecular docking and 3D-QSAR were applied to evaluate the interaction effects between 178 antioxidant phytochemicals and the Nrf2 binding site in Keap1. The Nrf2 activation effect was tested on a H 2 O 2 -induced oxidative-injured cell model. Results showed that the 178 phytochemicals could be divided into high-, medium-, and low-total-score groups depending on their binding affinity with Keap1, and the high-total-score group consisted of 24 compounds with abundant oxygen or glycosides. Meanwhile, these compounds could bind with key amino acids in the structure of the Keap1-Nrf2 interface. Compounds from high-total-score group show effective activation effects on Nrf2. In conclusion, phytochemicals showed high binding affinity with Keap1 are promising new Nrf2 activators., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Phenolic compounds could be sensitive to digestive conditions, thus a simulated in vitro digestion-dialysis process and cellular assays was used to determine phenolic compounds and antioxidant and antiproliferative potentials of 10 common edible flowers from China and their functional components., Results: Gallic acid, ferulic acid, and rutin were widely present in these flowers, which demonstrated various antioxidant capacities (DPPH, ABTS, FRAP and CAA values) and antiproliferative potentials measured by the MTT method. Rosa rugosa, Paeonia suffruticosa and Osmanthus fragrans exhibited the best antioxidant and antiproliferative potentials against HepG2, A549 and SGC-7901 cell lines, except that Osmanthus fragrans was not the best against SGC-7901 cells. The in vitro digestion-dialysis process decreased the antioxidant potential by 33.95-90.72% and the antiproliferative potential by 13.22-87.15%. Following the in vitro digestion-dialysis process, phenolics were probably responsible for antioxidant (R 2 = 0.794-0.924, P < 0.01) and antiproliferative (R 2 = 0.408-0.623, P < 0.05) potential. Moreover, gallic acid may be responsible for the antioxidant potential of seven flowers rich in edible flowers., Conclusion: The antioxidant and antiproliferative potential of 10 edible flowers revealed a clear decrease after digestion and dialysis along with the reduction of phenolics. Nevertheless, they still had considerable antioxidant and antiproliferative potential, which merited further investigation in in vivo studies. © 2017 Society of Chemical Industry., (© 2017 Society of Chemical Industry.)

Variations of phenylethanoid glycoside profiles and antioxidant activities in Osmanthus fragrans flowers through the digestive tract were evaluated by a simulated digestion model and UPLC/PDA/MS. Major phenylethanoid glycosides and phenolic acids, namely, salidroside, acteoside, isoacteoside, chlorogenic acid, and caffeic acid, were identified in four cultivars of O. fragrans flowers, and the concentration of acteoside was the highest, being up to 71.79 mg/g dry weight. After simulated digestion, total phenylethanoid glycoside contents and antioxidant activities were significantly decreased. Acteoside was identified as decomposing into caffeic acid, whereas salidroside was found to be stable during simulated digestion. According to Pearson's correlation analysis, acteoside contents showed good correlations with antioxidant activities during simulated digestion (R(2) = 0.994, P < 0.01). In conclusion, acteoside was the major contributor to the antioxidant activity of O. fragrans flowers, and salidroside was considered as the major antioxidant compound of O. fragrans flowers in vivo.

Acteoside has been reported to have antioxidant and neuroprotective effect, which is a promising therapeutic way in prevention and treatment of Parkinson's disease. The present study was aimed to understand the neuroprotective effect of acteoside and to elucidate its underlying mechanism. 6-hydroxydopamine (6-OHDA)-induced neural damage in zebrafish model was used to study the protective effect of acteoside on Parkinson's disease (PD). Locomotion behavioral test showed that acteoside could prevent 6-OHDA-stimulated movement disorders. Anti-tyrosine hydroxylase (TH) whole-mount immunostaining analysis showed that acteoside could prevent 6-OHDA-induced dopaminergic neuron death. In addition, pretreatment with acteoside could upregulate antioxidative enzymes by activating the Nrf2/ARE signaling pathway in zebrafish. Meanwhile, acteoside was found to be distributed in the brain after intraperitoneal injection into the adult zebrafish, indicating that this compound could penetrate the blood-brain-barrier (BBB). This study demonstrated that acteoside could penetrate BBB and have potential therapeutic value for PD by activating the Nrf2/ARE signaling pathway and attenuating the oxidative stress. [ABSTRACT FROM AUTHOR]

This study was aimed to classify the varieties and predict the antioxidant activity of Osmanthus fragrans flowers by UPLC–PDA/QTOF–MS and multivariable analysis. The PLS–DA model successfully classified the four varieties based on both the 21 identified compounds and the effective compounds. For the antioxidant activity prediction, PLS performed well to predict the antioxidant activity of O. fragrans flowers. Furthermore, acteoside, suspensaside A, ligustroside, forsythoside A, phillygenin and caffeic acid were selected as effective compounds by UVE–SPA for prediction. On the basis of effective compounds, PLS, MLR and PCR were applied to establish the calibration models. The UVE–SPA–MLR model was the optimal method to predict the antioxidant activity values with R p of 0.9200, 0.9010 and 0.8905 for DPPH, ABTS and FRAP assays, respectively. The results revealed that the UPLC–PDA/QTOF–MS combined with chemometrics could be a new method to classify the varieties and predict the antioxidant activity of O. fragrans flowers. [ABSTRACT FROM AUTHOR]