Vine Tea Research Articles

Dihydromyricetin Attenuates Myocardial Hypertrophy Induced by Transverse Aortic Constriction via Oxidative Stress Inhibition and SIRT3 Pathway Enhancement.

Dihydromyricetin (DMY), one of the flavonoids in vine tea, exerts several pharmacological actions. However, it is not clear whether DMY has a protective effect on pressure overload-induced myocardial hypertrophy. In the present study, male C57BL/6 mice aging 8–10 weeks were subjected to transverse aortic constriction (TAC) surgery after 2 weeks of DMY (250 mg/kg/day) intragastric administration. DMY was given for another 2 weeks after surgery. Blood pressure, myocardial structure, cardiomyocyte cross-sectional area, cardiac function, and cardiac index were observed. The level of oxidative stress in the myocardium was assessed with dihydroethidium staining. Our results showed that DMY had no significant effect on the blood pressure. DMY decreased inter ventricular septum and left ventricular posterior wall thickness, relative wall thickness, cardiomyocyte cross-sectional areas, as well as cardiac index after TAC. DMY pretreatment also significantly reduced arterial natriuretic peptide (ANP), brain natriuretic peptide (BNP) mRNA and protein expressions, decreased reactive oxygen species production and malondialdehyde (MDA) level, while increased total antioxidant capacity (T-AOC), activity of superoxide dismutase (SOD), expression of sirtuin 3 (SIRT3), forkhead-box-protein 3a (FOXO3a) and SOD2, and SIRT3 activity in the myocardium of mice after TAC. Taken together, DMY ameliorated TAC induced myocardial hypertrophy in mice related to oxidative stress inhibition and SIRT3 pathway enhancement.

Agricultural Environmental Monitoring Data Classification of Fanjing Mountains: A Decision Tree Approach

Fanjing Mountains is rich in wildlife resources (such as Guizhou golden monkey, dove tree, and other rare species) and tea resources (for example, Fanjing Mountains cui feng tea, Shiqian moss tea, Vatican black tea, Jin Qiangong black tea, Eight hour black tea, vine tea and other dozens of products), where is completely unable to find traces of artificial scenery, and its main peak “mushroom stone” is a landscape. So it has great important scientific and ecological value in researching the classification of agriculture environment data in Fanjing Mountains, so as to develop various sensors about new crops of growth environment factors (e.g. soil temperature, soil moisture content, air temperature, air humidity, light intensity and carbon dioxide (CO2) concentration), as well as the biometric information of individual animals (e.g. body temperature, pulse, location information), realize the intellectualization of agriculture, establish administrative policy with the pilot of scientific research, the basis of management and protection, and the guarantee of coordination, better promote the green development of agriculture, and assure the security of resource and ecology. This article analyzes the agricultural environment monitoring data adopting the classification method of decision tree in machine learning.

Effects of Extraction Variables on Pharmacological Activities of Vine Tea Extract (Ampelopsis grossedentata)

Effects of Extraction Variables on Pharmacological Activities of Vine Tea Extract (Ampelopsis grossedentata)

Interactions of Dihydromyricetin, a Flavonoid from Vine Tea (Ampelopsis grossedentata) with Gut Microbiota.

The gut microbiota plays an important role in the pharmacokinetics of flavonoids. As well, the long-term supplements of flavonoids could alter the gut microbiota composition in turn. The study aims to clarify the mutual interaction of DMY with gut microbiota, which may lead to new information with respect to the mechanism study and clinical application of DMY.

Dihydromyricetin from Vine Tea ( <i>Ampelopsis grossedentata</i>) Prevents Diet-Induced Obesity by Modulating the Gut Microbiota Composition

Background: Gut microbiota plays a decisive role in the pathogenesis of obesity. Targeting the gut microbiota are potential therapies for obesity. Dihydromyricetin (DMY), a flavanonol compound isolated from vine tea (Ampelopsis grossedentata) in the traditional Chinese medicine, improves glucose and lipid metabolism despite of low bioavailability. Methods: Mice were fed with a normal chow diet (NCD) or high-fat diet (HFD), and HFD-fed mice was supplemented with DMY once daily by intragastric gavage for 13 weeks. Serum lipopolysaccharide (LPS) was measured by ELISA, and expressions of tight junction proteins in colon and pro-inflammatory cytokines in liver and epididymal adipose tissues were determined by quantitative PCR. The gut microbiota was analyzed by 16S rDNA sequencing. Using the method combined gut microbiota depletion and repopulation in HFD-fed mice, the causation that DMY reduces obesity by targeting the gut microbiota was explored. Results: DMY reduced body weight gain, fat accumulation and hepatic steatosis, and improved glucose homeostasis and insulin sensitivity in HFD-fed mice. The metabolic endotoxemia, chronic low-grade inflammation and leaky gut were alleviated. DMY reverses the gut microbiota of HFD-fed mice to the composition similar with that of NCD-fed mice. Moreover, the beneficial effects of DMY on HFD-induced obesity were eliminated by gut microbiota depletion, and were subsequently restored together with the modulation of gut microbiota composition after microbiota repopulation. Conclusions: Supplementation of DMY from vine tea represents an effective and implementable strategy that modulates the potentially beneficial gut commensal bacteria to prevent obesity, non-alcoholic fatty liver disease and type 2 diabetes. Funding Statement: This study was financially supported by the National Natural Science Foundation of China (No. 81503013) and Natural Science Foundation of Hubei Province (No. 2017CFB481). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: The animal experiment was approved by the Institutional Animal Care and Use Committee at Tongji Medical College, Huazhong University of Science and Technology (IACUC No. S769).

Optimizing the Maximum Recovery of Dihydromyricetin from Chinese Vine Tea, Ampelopsis grossedentata, Using Response Surface Methodology.

This work provides an optimized extraction approach intended to maximize the recovery of dihydromyricetin (DHM) from Chinese vine tea (Ampelopsis grossedentata) leaves. The presented work adopts a Box-Behnken design as a response surface methodology to understand the role and influence of specific extraction parameters including: time, temperature, and solvent composition/ethanol (%) on DHM final yields. Initially, single factor experiments were used to delineate the role of above factors (temperature, time, and solvent composition) before proceeding with three factors-three levels Box-Behnken design with 17 separate runs to assess the effect of multifactorial treatments on DHM recovery rates. The collected data shows that independent variables (solvent composition, time, and temperature) can significantly affect DHM recovery rates with maximum yields resulting from a combined 60 °C, 60% aqueous ethanol, and 180 min treatment. From the empirical point of view, the above optimized extraction protocol can substantially enhance processing and profitability margins with a minimum need of interventions or associated costs.

Metabolomics reveals that vine tea (Ampelopsis grossedentata) prevents high-fat-diet-induced metabolism disorder by improving glucose homeostasis in rats.

BackgroundVine tea (VT), derived from Ampelopsis grossedentata (Hand.-Mazz.) W.T. Wang, is an alternative tea that has been consumed widely in south China for hundreds of years. It has been shown that drinking VT on a daily basis improves hyperlipidemia and hyperglycemia. However, little is known about the preventive functions of VT for metabolic dysregulation and the potential pathological mechanisms involved. This paper elucidates the preventive effects of VT on the dysregulation of lipid and glucose metabolism using rats maintained on a high-fat-diet (HFD) in an attempt to explain the potential mechanisms involved.MethodsSprague Dawley (SD) rats were divided into five groups: a group given normal rat chow and water (control group); a group given an HFD and water (HFD group); a group given an HFD and Pioglitazone (PIO group), 5 mg /kg; and groups given an HFD and one of two doses of VT: 500 mg/L or 2000 mg/L. After 8 weeks, changes in food intake, tea consumption, body weight, serum and hepatic biochemical parameters were determined. Moreover, liver samples were isolated for pathology histology and liquid chromatography-mass spectrometry (LC-MS)-based metabolomic research.ResultsVT reduced the serum levels of glucose and total cholesterol, decreased glucose area under the curve in the insulin tolerance test and visibly impaired hepatic lipid accumulation. Metabolomics showed that VT treatment modulated the contents of metabolic intermediates linked to glucose metabolism (including gluconeogenesis and glycolysis), the TCA cycle, purine metabolism and amino acid metabolism.ConclusionThe current results demonstrate that VT may prevent metabolic impairments induced by the consumption of an HFD. These effects may be caused by improved energy-related metabolism (including gluconeogenesis, glycolysis and TCA cycle), purine metabolism and amino acid metabolism, and reduced lipid levels in the HFD-fed rats.

Dihydromyricetin protects human umbilical vein endothelial cells from injury through ERK and Akt mediated Nrf2/HO-1 signaling pathway.

Atherosclerosis-related cardiovascular disease is the predominant cause of death worldwide. Ox-LDL-induced vascular endothelial cell injury is a major factor in the pathogenesis of atherosclerosis. Dihydromyricetin (DMY) is a flavonoid extracted from vine tea that exerts multiple pharmacological activities, including cardio-protective, anti-tumor, and anti-oxidative effects. However, it is unreported that DMY shows protective effects on ox-LDL-induced endothelial cell injury. In this study, we used an ox-LDL injured human umbilical vein endothelial cell (HUVEC) in vitro model to explore the protective effects and mechanism of DMY. HUVECs were pretreatment with DMY and then exposed to ox-LDL, the cell viability was measured. Then, the anti-oxidative enzymes were tested by commercial kits and intracellular reactive oxygen species (ROS) was measured by flow cytometry, cell apoptosis was determined by Annexin-V/PI assay and apoptosis-related proteins were detected by western blot. Our results showed that DMY pretreatment provided cytoprotective effects by suppressing ox-LDL-induced endothelial cell apoptosis, mitochondrial membrane depolarization, caspase-3 activation, and modulation of oxidative enzymes, thereby inhibiting ROS generation. The anti-oxidative and anti-apoptotic effects of DMY were abrogated by the transfection of Nrf2 siRNAs and HO-1 inhibitor ZnPP. Furthermore, DMY might activate the Nrf2/HO-1 pathway through activation of the Akt and ERK1/2 pathways, as shown by the inhibition of Nrf2/HO-1 signaling by the inhibitors PD98059 or LY294002 and the transfection of ERK, Akt siRNAs. In this study, DMY protects HUVECs from ox-LDL-induced oxidative injury by activating Akt and ERK1/2, which subsequently activates Nrf2/HO-1 signaling, thereby up-regulating antioxidant enzymes and anti-apoptotic proteins.

Tissue Distribution, Excretion, and Metabolic Profile of Dihydromyricetin, a Flavonoid from Vine Tea (Ampelopsis grossedentata) after Oral Administration in Rats.

Dihydromyricetin (DMY), a flavanonol compound found as the most abundant and bioactive constituent in vine tea (Ampelopsis grossedentata), possesses numerous biological activities. In the present study, an HPLC-MS/MS method for the determination of DMY in tissues, urine, and feces was developed and applied to the tissue distribution and excretion study after oral administration in rats, and the metabolic profile of DMY was further investigated using UPLC-QTOF-MS. The results indicated that DMY could be distributed rapidly in various tissues and highly in the gastrointestinal tract. The elimination of DMY occurred rapidly as well, and most unconverted forms were excreted in feces. A total of eight metabolites were identified in urine and feces, while metabolites were barely found in plasma. The predicted metabolic pathways including reduction, dehydroxylation, methylation, glucuronidation, and sulfation were proposed. The present findings may provide the theoretical basis for evaluating the biological activities of DMY and will be helpful for its future development and application.

Dihydromyricetin attenuated Ang II induced cardiac fibroblasts proliferation related to inhibitory of oxidative stress

Dihydromyricetin (DMY) is one of the most important flavonoids in vine tea, which showed several pharmacological effects. However, information about the potential role of DMY on angiotensin II (Ang II) induced cardiac fibroblasts proliferation remains unknown. In the present study, cardiac fibroblasts isolated from neonatal Sprague-Dawley rats were pretreated with different concentrations of DMY (0–320μM) for 4h, or DMY (80μM) for different time (0–24h), followed by Ang II (100nM) stimulation for 24h, Then number of cardiac fibroblasts and content of hydroxyproline was measured. The level of cellular reactive oxygen species, malondialdehyde (MDA), activity of superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) were also evaluated. Expression of type I, type III collagen, α-smooth muscle actin (α-SMA), p22phox (one vital subunit of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase), SOD and thioredoxin (Trx) were detected with real time PCR or/and western blot. We found that pre-incubation with DMY (20μM, 40μM, 80μM) for 4h, 12h or 24h attenuated the proliferation of cardiac fibroblasts induced by Ang II. Expression of type I and type III collagen, as well as α-SMA were inhibited by DMY at both mRNA and protein level. DMY also significantly decreased cellular reactive oxygen species production and MDA level, while increased the SOD activity and T-AOC. DMY suppressed p22phox, while enhanced antioxidant SOD and Trx expression in Ang II stimulated cardiac fibroblasts. Thus, dihydromyricetin attenuated Ang II induced cardiac fibroblasts proliferation related to inhibitory of oxidative stress.

At-line hyphenation of high-speed countercurrent chromatography with Sephadex LH-20 column chromatography for bioassay-guided separation of antioxidants from vine tea (Ampelopsis grossedentata).

Vine tea (Ampelopsis grossedentata), a widely used healthy tea, beverage and herbal medicine, exhibited strong antioxidant activity. However, systematic purification of antioxidants, especially for those with similar structures or polarities, is a challenging work. Here, we present a novel at-line hyphenation of high-speed countercurrent chromatography with Sephadex LH-20 column chromatography (HSCCC-Sephadex LH-20 CC) for rapid and efficient separation of antioxidants from vine tea target-guided by 1,1-diphenyl-2-picryl-hydrazyl radical-high performance liquid chromatography (DPPH-HPLC) experiment. A makeup pump, a six-port switching valve and a trapping column were served as interface. The configuration had no operational time and mobile phase limitations between two dimensional chromatography and showed great flexibility without tedious sample-handling procedure. Seven targeted antioxidants were firstly separated by stepwise HSCCC using petroleum ether-ethyl acetate-methanol-water (4:9:4:9, v/v/v/v) and (4:9:5:8, v/v/v/v) as solvent systems, and then co-eluted antioxidants were on-line trapped, concentrated and desorbed to Sephadex LH-20 column for further off-line purification by methanol. It is noted that six elucidated antioxidants with purity over 95% exhibited stronger activity than ascorbic acid (VC). More importantly, this at-line hyphenated strategy could sever as a rapid and efficient pathway for systematic purification of bioactive components from complex matrix.

Antioxidant profiling of vine tea (Ampelopsis grossedentata): Off-line coupling heart-cutting HSCCC with HPLC-DAD-QTOF-MS/MS.

Vine tea with strong antioxidant activity is commonly consumed as healthy tea/beverage. However, detailed information about its antioxidants is incomplete. Here, off-line hyphenation of heart-cutting high-speed countercurrent chromatography (HSCCC) with high performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry (HPLC-DAD-QTOF-MS/MS) were described for systematic profiling antioxidants in vine tea. At first, antioxidants were rapidly screened by 1,1-diphenyl-2-picryl-hydrazyl radical-high performance liquid chromatography (DPPH-HPLC). Subsequently, stepwise HSCCC using petroleum ether-ethyl acetate-methanol-water (4:9:4:9, v/v/v/v) and (4:9:5:8, v/v/v/v) as solvent systems was optimized to fractionate and enrich antioxidants from ethyl acetate fraction of vine tea. Finally, heart-cutting mode was used to collect five interesting HSCCC fractions for HPLC-DAD-QTOF-MS/MS analysis. Desirable orthogonality between HSCCC and HPLC led to identification of fifteen antioxidant flavonoids, while four minor flavonoids were first reported in vine tea. Results showed that the developed system is efficient to comprehensively explore antioxidants from complex natural herbs.

The cardioprotective effect of dihydromyricetin prevents ischemia–reperfusion-induced apoptosis in vivo and in vitro via the PI3K/Akt and HIF-1α signaling pathways

Reperfusion therapy is widely used to treat acute myocardial infarction (AMI). However, further injury to the heart induced by rapidly initiating reperfusion is often encountered in clinical practice. A lack of pharmacological strategies in clinics limits the prognosis of patients with myocardial ischemia-reperfusion injury (MIRI). Dihydromyricetin (DMY) is one of the most abundant components in vine tea, commonly known as the tender stems and leaves of Ampelopsis grossedentata. The aim of this study was to evaluate the cardioprotection of DMY against myocardial ischemia-reperfusion (I/R) injury and to further investigate the underlying mechanism. An I/R injury was induced by left anterior descending coronary artery occlusion in adult male rats in vivo and a hypoxia-reoxygenation (H/R) injury in H9c2 cardiomyocytes in vitro. We found that DMY pretreatment provided significant protection against I/R-induced injury, including enhanced antioxidant capacity and inhibited apoptosis in vivo and in vitro. This effect correlated with the activation of the PI3K/Akt and HIF-1α signaling pathways. Conversely, blocking Akt activation with the PI3K inhibitor LY294002 effectively suppressed the protective effects of DMY against I/R-induced injury. In addition, the PI3K inhibitor partially blocked the effects of DMY on the upregulation of Bcl-2, Bcl-xl, procaspase-3, -8, and -9 protein expression and the downregulation of HIF-1α, Bnip3, Bax, Cyt-c, cleaved caspase-3, -8, and -9 protein expression. Collectively, these results showed that DMY decreased the apoptosis and necrosis by I/R treatment, and PI3K/Akt and HIF-1α plays a crucial role in protection during this process. These observations indicate that DMY has the potential to exert cardioprotective effects against I/R injury and the results might be important for the clinical efficacy of AMI treatment.

Optimization of the Ultrasonic-Assisted Extraction of Bioactive Flavonoids from Ampelopsis grossedentata and Subsequent Separation and Purification of Two Flavonoid Aglycones by High-Speed Counter-Current Chromatography.

The fermented leaf of Ampelopsis grossedentata has been used as a beverage and folk medicine called “vine tea” in the southern region of China. In this paper, the optimum extraction conditions for the maximum recovery amounts of total flavonoids (TF), dihydromyricetin (DMY), myricitrin (MYG) and myricetin (MY) from natural Ampelopsis grossedentata leaves subjected to ultrasonic-assisted extraction (UAE) were determined and optimized by using response surface methodology. The method was employed by the Box–Behnken design (BBD) and Derringer’s desirability function using methanol concentration, extraction time, liquid/solid ratio as factors and the contents of TF, DMY, MYG and MY as responses. The obtained optimum UAE conditions were as follows: a solvent of 80.87% methanol, an extraction time of 31.98 min and a liquid/solid ratio of 41.64:1 mL/g. Through analysis of the response surface, it implied that methanol concentration and the liquid/solid ratio had significant effects on TF, DMY, MYG and MY yields, whereas extraction time had relatively little effects. The established extraction and analytical methods were successfully applied to determine the contents of the total flavonoids and three individual flavonoids in 10 batches of the leaf samples of A. grossedentata from three counties in Fujian Province, China. The results suggested the variability in the quality of A. grossedentata leaves from different origins. In addition, high purities of dihydromyricetin and myricetin were simultaneously separated and purified from the extract subjected to optimized UAE, by high-speed counter-current chromatography using a solvent system of N-hexane–ethyl acetate–methanol–water (1:3:2:4; v/v/v/v). In a single operation, 200 mg of the extract were separated to yield 86.46 mg of dihydromyricetin and 3.61 mg of myricetin with the purity of 95.03% and 99.21%, respectively. The results would be beneficial for further exploiting the herbal products and controlling the quality of the herb and its derived products.

Biotransformation of vine tea (Ampelopsis grossedentata) by solid-state fermentation using medicinal fungus Poria cocos.

Vine tea was bio-transformed using Poria cocos by solid-state fermentation in order to improve its taste and quality. Volatile components in vine tea were also identified by GC-MS. The changes of flavonoid, tea polyphenols and polysaccharides in fermented vine tea were evaluated. Flavonoid and polyphenols in vine tea were remained unchanged even after biotransformation, but content of polysaccharides increased to 3.9-fold than that of unfermented vine tea. Antioxidant activity such as DPPH free radical scavenging capacity (SR) was determined that there was a positive correlation between SR and content of polysaccharides in vine tea. Methyl 2-methylvalerate-a new volatile compound was identified and gave the vine tea rich delicate fragrance of fruits. The content of linolenic acid increased from 0.88 to 19.59%. Biotransformation improved the taste and quality of vine tea.

RAPID SEPARATION AND IDENTIFICATION OF MULTIPLE CONSTITUENTS IN VINE TEA BY UFLC SYSTEM COUPLED WITH Q-TOF-MS/MS

Vine Tea (VT), as a well - known Chinese traditional liana medicine and functional tea, is a special plant which is rich in flavonoids; even though some ingredients were isolated via the conventional approach. Nevertheless, there have been no reports about chemical profile through LC - Q - TOF - MS/MS. In this study, an method has been established to rapid separation and structural identification the chemical constituents of Vine Tea fo r the first time by ultra - fast liquid chromatography coupled with quadrupole/time - of - flight mass spectra (UFLC - Q - TOF - MS/MS). Based on the accurate mass, retention time and MS spectra, 29 compounds in crude extract, mainly belonging to flavonoids and organi c acids, were explicitly identified or tentatively characterized by comparing with reference standards or literatures. The possible fragmentation pathways were proposed and fragmentation rules of the maj or types of compounds were concluded. The results ind icated that UFLC - Q - TOF - MS/MS based chemical profiling is a highly efficient approach for the original discrimination of Vine Tea as well as other traditional Chinese medicines.

Dihydromyricetin protects endothelial cells from hydrogen peroxide-induced oxidative stress damage by regulating mitochondrial pathways.

Dihydromyricetin (DMY) is the most abundant ingredient in vine tea. Here, we investigated the cytoprotective effects and possible mechanisms of DMY on hydrogen peroxide (H2O2)-induced oxidative stress damage in human umbilical vein endothelial cells (HUVECs). The percentage of cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. We determined the antioxidant properties of DMY by measuring the activity of superoxide dismutase (SOD) and malondialdehyde (MDA). Flow cytometry was used to measure apoptosis in HUVECs that were double stained with Hoechst 33342 and propidium iodide (PI). The generation of intracellular reactive oxygen species (ROS) was measured in 2',7'-dichlorofluorescin diacetate (DCFH-DA)-loaded HUVECs using a fluorescent microscope. Moreover, the expression of apoptosis-related proteins was determined by Western blotting. In addition, the release of nitric oxide (NO) was analyzed using a commercial kit. HUVECs treated with H2O2 had a notable decrease in cell viability that was attenuated when cells were pretreated with DMY (37.5-300μM). DMY pretreatment significantly attenuated H2O2-induced apoptosis in HUVECs and inhibited intracellular ROS overproduction. Finally, pretreatment of cells with DMY prior to H2O2 exposure resulted in the inhibition of p53 activation, followed by the regulation of the expression of Bcl-2 and Bax, the release of cytochrome c, the cleavage (activation) of caspase-9 and caspase-3, and then the suppression of PARP cleavage in H2O2-induced HUVECs. Our study is the first to report that DMY can protect HUVECs from oxidative stress damage, an effect that is mediated by the mitochondrial apoptotic pathways.

Antioxidant activities of Vine Tea (Ampelopsis grossedentata) extract and its major component dihydromyricetin in soybean oil and cooked ground beef

Antioxidant activities of Ampelopsis grossedentata extract (EXT) and its major component dihydromyricetin (DHM) were analysed and compared with BHA in two model systems, soybean oil and cooked ground beef. Oxidation of soybean oil samples was measured using peroxide value, anisidine value, headspace volatiles and headspace oxygen content. TBARS (thiobarbituric acid reactive substances) test was used to measure the oxidation of cooked beef. DHM was more potent than BHA in preventing soybean oil oxidation. EXT was not as effective as BHA or DHM in soybean oil. In cooked beef, all three antioxidants significantly lowered oxidation compared to control, but there were no differences between the three. Mechanisms and potentials of EXT and DHM as natural food antioxidants need to be studied on a case-by-case basis.

Biosynthesis of Gold Nanoparticles Using Vine Tea Powder Extracts

Gold nanoparticles were prepared by a bioreduction of chloroauric acid with vine tea powder extracts,and characterized by UV-Vis, TEM and size distribution. The process of biosynthesis was investigated by control variate method. The results show that pH of the reaction solution,temperature and the quantities of the chloroauric acid all have significant effects on the particle size,size distribution,morphology and stability of gold nanoparticles. At pH 6. 47 or in the presence of excess vine tea powder extracts,gold nanoparticles tend to agglomerate and the size of gold nanoparticles increases with the temperature increasing.Therefore,an effective controllable green synthesis of gold nanoparticles can be realized by control variate method.

Composition and serum antioxidation of the main flavonoids from fermented vine tea (Ampelopsis grossedentata)

Ampelopsis grossedentata (vine tea) contains the highest amount of flavonoids in plant resources, and has been developed as a functional tea in recent years in China. Dihydromyricetin is the main flavonoid in vine tea. Vine tea is produced by natural process of fermentation. However, there have been no reports about the composition of flavonoids in fermented vine tea. In this study, the flavonoids of naturally fermented vine tea were identified as 3-dihydroxyquercetin, dihydromyricetin, isodihydromyricetin, myricetin-3-rahmnose and myricetin. Dihydromyricetin was the main flavonoid in fermented vine tea. Reductive levels of rat serum against DPPH reached the highest at fourth hour after administration with dihydromyricetin at 100 mg/kg and decreased after fourth hour. Compared to dihydromyricetin, the total flavonoids showed the same time dependence but with a higher antioxidation activity.