The levels of bioactive ingredients in Citrus aurantium L. at different harvest periods and antioxidant effects on H2 O2 -induced RIN-m5F cells.

BACKGROUND: Citrus aurantium L. (Aurantii fructus) is a multi-purpose citrus fruit with high medicinal and nutritional value, but currently there are no data that can be used to investigate the appropriate harvest time to obtain high-quality citrus bioactive ingredients from it. RESULTS: Phytochemicals and the levels of the main bioactive ingredients were investigated by ultra high performance liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF/MS). The flavanone, polymethoxyflavone, coumarin, synephrine, and limonin content in the citrus fruit was analyzed at different harvest periods, and significant differences, ranging from 0.03 ± 0.01 to 116.26 ± 40.20 g kg-1 (DW), were shown. These compounds were present in higher amounts in June and then decreased gradually, while the biomass accumulation of most of them showed an increasing tendency around harvest time. The H2 O2 -induced RIN-m5F cells model was employed to evaluate their antioxidant capacity. Citrus fruit harvested from June 11 to July 7 possessed an excellent antioxidant capacity by inhibiting the intensity of intracellular reactive oxygen species (ROS) (P < 0.01) and improving superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH) activity (P < 0.01). The chemical composition and antioxidant capacity of citrus leaves, stems, and roots were also evaluated, and these showed great variation compared with other citrus fruits. Multivariate statistical analysis indicated that harvesting time was related closely to the phytochemical contents and antioxidant capacity. CONCLUSION: Citrus fruit can be appropriately harvested from June to early July when the levels of bioactive ingredients and antioxidant activity reach higher values. This research provides practical information for producing high-quality citrus products. © 2020 Society of Chemical Industry.

Comparative investigation of phytochemicals among ten citrus herbs by ultra high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry and evaluation of their antioxidant properties.

The citrus herbs have proved their important medicinal and nutritional values as medicine-food dual-purpose herbs, functional foods, or medical herbs in China. In this study, phytochemicals and antioxidant activity among ten typical citrus herbs (ethanol extracts) were investigated comprehensively. The major ingredients and their contents were analyzed by high-resolution mass spectrometry, and the differences of typical fragment ions between flavanone-7-O-rutinoside(s) and flavanone-7-O-neohesperidoside(s) were discriminated properly in negative electrospray ionization mode. Total polyphenols, total flavonoids, 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), and ferric reducing antioxidant power tests were performed, which indicated their beneficial values and antioxidant effects. The medicine-food dual-purpose herbs including Chenpi, Juluo, Daidaihua, Huajuhong, Xiangyuan, and Foshou exhibited antioxidant capacities significantly by decreasing intracellular reactive oxygen species intensity (P < 0.01), enhancing superoxide dismutase, catalase, and glutathione peroxidase activities (P < 0.01) in H2 O2 -induced RIN-m5F cells. Moreover, the functional foods Zhishi, Zhiqiao, and Qingpi showed moderate antioxidant bioactivity, while the medical herb Juhe showed weak antioxidant bioactivity, which were consistent with the multivariate analysis of their major flavonoids. The study provided a new sight for the chemical differentiation and practical application of citrus herbs as medicine-food dual-purpose herbs, functional foods, or medical herbs.

Lignans from Eucommia ulmoides Oliver leaves exhibit neuroprotective effects via activation of the PI3K/Akt/GSK-3ß/Nrf2 signaling pathways in H2O2-treated PC-12 cells.

BACKGROUND: Neuronal apoptosis and oxidative stress have the most crucial influence on neurodegenerative diseases, including Parkinson's disease. Rat adrenal pheochromocytoma cells (PC-12) induced by H2O2 are one of the primary in vitro models of Parkinson's disease (PD) . Previous studies have found that E ulmoides leaf extract exerts good neuroprotective activity and has the potential to treat neurodegenerative diseases. However, the molecular pathways involved in the neuroprotective effects of its primary leaf component, lignans, have not yet been well elucidated yet. PURPOSE: This study aimed to evaluate the neuroprotective effects of lignans in E. ulmoides leaves and to explore the underlying mechanism. METHODS: Cell viability was measured using the CCK-8 assay. Apoptosis was assessed by calcein/PI staining. The release levels of ROS and LDH were assessed using a commercial assay kit. The enzyme activities of SOD and GPx were measured using kits. The establishment of the compound-target-pathway-disease network was performed using a database and computer software. Antioxidant proteins (HO-1, NQO-1, and Cat) and related regulatory proteins (Nrf2, GSK-3ß, p-GSK 3ß (Ser 9), Akt, p-Akt (Tyr326), PI3K) were detected by western blotting. Apoptosis in the zebrafish head was assessed using acridine orange (AO) staining. RESULTS: In the present study, 12 lignans were isolated and characterized from E. ulmoides leaves, including a new compound, (-)-7­epi-pinoresinol mr1 (1). Compounds 1-12 exerted neuroprotective effects in H2O2-treated PC-12 cells by increasing cell viability, improving the enzyme activity of SOD and GPx, and reducing levels of ROS and LDH. Compared to the positive control group (25 µM hesperetin), cell viability in response to 25 µM compound 1 (78.0 ± 0.8%) was highest, but its relative percent LDH release (20.1 ± 2.5%) was the lowest; 25 µM compound 4 resulted in the lowest ROS release levels (101.7 ± 2.6%) and highest SOD enzyme activity (35.9 ± 4.2 U/mg), and the GPx enzyme activity of 25 µM compound 1 was strongest (197.6 ± 0.6 U/mg). Next, the potential targets (PI3K, GSK-3ß) of the test compounds' antioxidant activity were identified using pharmacological network analysis. Using DAVID software for pharmacological network analysis, potential targets (PI3K, GSK-3ß, and SOD2) of 12 lignans were identified. Based on the initial screening results, biological experiments confirmed that diepoxylignans 1, 2, and 4 exerted significant neuroprotection by regulating the PI3K/AKT/GSK-3ß/Nrf2 signaling pathways, increasing protein expression of HO-1, NQO-1, and CAT, and enhancing the antioxidant enzyme activity of SOD and GPx. CONCLUSION: Our experiments first propose that the diepoxylignans from E. ulmoides leaves exert neuroprotective effects via activation of the PI3K/Akt/GSK-3ß/Nrf2 signaling pathway. These findings further indicate that lignans could be the primary components of E. ulmoides Oliver as agents for the prevention and treatment of neurodegenerative diseases. Collectively, Eucommia ulmoides leaves with important research value may be a potential candidate for traditional Chinese medicine for treating oxidative stress-related neurodegenerative diseases.