Quercetin-3-O-β-d-glucopyranoside, a dietary flavonoid, protects PC12 cells from H2O2-induced cytotoxicity through inhibition of reactive oxygen species

et al. 2019

J Sci Food Agric

BACKGROUND: Greater proportions of purple tea buds and leaves usually appear in the summer, which seriously affects the color and taste quality of green tea products, yet the metabolism of purple tea shoots in summer remains unclear. Here, the metabolomic profiles and gene expression of related flavonoid metabolic pathways in the purple and normal green shoots of 'Longjing 43', and the quality of green tea made with these two phenotypes, were analyzed and compared. RESULTS: Differential metabolites identified using high-performance liquid chromatography-Orbitrap/mass spectrometry indicated that anthocyanin biosynthesis in purple leaves was enriched, with higher levels of anthocyanidins (delphinidin-hexose-coumaroyl showed the greatest increase), proanthocyanidins (oligomers of catechins) and kaempferol glycoside. Expression patterns of the genes ANR, ANS, FLS, LAR, C4H, PAL, CHI, CHS and DFR revealed that the metabolism of anthocyanin is positively regulated by high temperature and/or light levels in summer. Gas chromatography-mass spectrometry results showed that, in purple tea shoots, the metabolism of carbohydrates was enriched whereas that of amino acids was diminished, while their mannose, fructose, D-galactose, sorbose and D-glucose contents were more than double those found in green leaves. A sensory evaluation confirmed that a greater quantity of purple shoots had a greater negative impact on green tea quality because of a bitter taste and dark color (leaves and infusions were tested).CONCLUSIONS: These results highlight the need for and possibility of improving commercial tea quality via cultivation that controls the temperature or light of tea gardens during the summer. Gene expression analysis of flavonoid metabolismTo further verify the change in flavonoid(s) metabolic pathways based on gene expression levels, the relative expression level of major genes known to be involved in flavonoid metabolism were detected using qRT-PCR. The results showed that the upstream PAL gene, and the downstream assimilation ANR gene and the ANS J Sci Food Agric 2020; 100: 1505-1514 DISCUSSION Flavonoid biosynthesis in purple tea shootsSecondary metabolism is widely understood to play a critical role in how plants respond to environmental stresses. 22 Flavonoids are the most important secondary metabolites found in the tea plant, J Sci Food Agric 2020; 100: 1505-1514

Section: Discussionsupporting

confidence: 45%

Stimulated biosynthesis of delphinidin‐related anthocyanins in tea shoots reducing the quality of green tea in summer

Zhang

et al. 2019

J Sci Food Agric

“…Therapy choices for liver injury are few. Quercetin, a pigment (flavonoid) found in many plants and foods such as wine, apple, onions, green tea, berries and some herbs, has wide bioactivity, including anti-oxidative, anti-fibrotic and antiinflammatory effects [4][5][6][7]. Its protective effect on liver injury was previously identified [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Protective and therapeutic effects of nanoliposomal quercetin on acute liver injury in rats

Zhang

et al. 2020

BMC Pharmacol Toxicol

Background: Quercetin, a pigment (flavonoid) found in many plants and foods, has good effects on protecting liver function but poor solubility and bioavailability in vivo. A drug delivery system can improve the accumulation and bioavailability of quercetin in liver. In this study, we used liposomal nanoparticles to entrap quercetin and evaluated its protective and therapeutic effects on drug-induced liver injury in rats. Methods: The nanoliposomal quercetin was prepared by a thin film evaporation-high pressure homogenization method and characterized by morphology, particle size and drug content. Acute liver injury was induced in rats by composite factors, including carbon tetrachloride injection, high-fat corn powder intake and ethanol drinking. After pure quercetin or nanoliposomal quercetin treatment, liver function was evaluated by detecting serum levels of glutamic-pyruvic transaminase (GPT), glutamic-oxal acetic transaminase (GOT) and direct bilirubin (DBIL). Histology of injured liver tissues was evaluated by hematoxylin and eosin staining. Results: On histology, liposomal nanoparticles loading quercetin were evenly distributed spherical particles. The nanoliposomal quercetin showed high bioactivity and bioavailability in rat liver and markedly attenuated the liver index and pathologic changes in injured liver tissue. With nanoliposomal quercetin treatment, the serum levels of GPT, GOT and DBIL were significantly better than treated with pure quercetin. Using liposomal nanoparticles to entrap quercetin might be an effective strategy to reduce hepatic injury and protect hepatocytes against damage. Conclusion: Liposomal nanoparticles may improve the solubility and bioavailability of quercetin in liver. Furthermore, nanoliposomal quercetin could effectively protect rats against acute liver injury and may be a new hepatoprotective and therapeutic agent for patients with liver diseases.

“…Antioxidation could be, among others, an effect of scavenging of free radicals, metal chelation and enzyme inhibition. Flavonoids, especially quercetin derivatives, which are most abundant in the leaves of P. rotundifolia, are powerful antioxidants with anti-inflammatory and anti-cancerogenic effects [49]. The measurement of antioxidant activity in our study was performed using four colorimetric protocols on a microplate scale in cell-free systems.…”

Section: Antioxidant Activitymentioning

confidence: 99%

Phenolic Composition of the Leaves of Pyrola rotundifolia L. and Their Antioxidant and Cytotoxic Activity

et al. 2020

The leaves of Pyrola rotundifolia L. were extracted in the mixed solvent of methanol/acetone/water (2:2:1, v/v/v) and investigated for their phytochemical analysis and biological activity. Total phenolic and flavonoid contents were determined spectrophotometrically. A high content of phenols (208.35 mg GAE/g of dry extract), flavonoids (38.90 mg QE/g of dry extract) and gallotannins (722.91 GAE/g of dry extract) was obtained. Ultra-high performance liquid chromatography diode array detector tandem mass spectrometry (UHPLC–DAD–MS) allowed for the detection of 23 major peaks at 254 nm. The extract was analyzed for its antioxidant capacity using 2,2-diphenyl-1-picryl-hydrazyl (DPPH•) and 2,2′-azinobis[3-ethylbenzthiazoline]-6-sulfonic acid (ABTS•+) radical scavenging, metal chelating power and β-carotene-linoleic acid bleaching assays. The examined extract showed moderate radical scavenging and chelating activity, and good inhibiting ability of linoleic acid oxidation (EC50 = 0.05 mg/mL) in comparison to standards. The cytotoxic effect in increasing concentration on five types of leukemic cell lines was also investigated using trypan blue vital staining. It was found that the analyzed extract induced the apoptosis of all the tested cell lines. Our findings suggest that the leaves of P. rotundifolia are a source of valuable compounds providing protection against oxidative damage, hence their use in traditional medicine is justified.