| Daylily is an economic crop widely distributed in the north and south of my country and has both edible and medicinal value.According to research data,daylily contains a variety of flavonoids,which have antioxidant,anti-inflammatory and hypoglycemic effects,and have been widely used in food,pharmaceutical and cosmetic fields.Ningxia is one of the five main producing areas of daylily in the country.At present,the planting area of daylily reaches 170,000 mu.The unique geographical environment makes Ningxia daylily high quality and large quantity.It is one of Ningxia’s characteristic agricultural products and has become a pillar industry for local poverty alleviation.In this paper,taking daylily from the main producing areas of Ningxia,Shaanxi,Gansu and Hunan as the research object,and taking human hepatoma cells(HepG2)as the model object,the content determination,structure characterization,composition analysis and antioxidant research of daylily from different producing areas were carried out.,to provide relevant scientific basis for the technological upgrading of Ningxia daylily industry.The main research contents are as follows:(1)Extraction of total flavonoids from daylily was assisted by ultrasound,and the extraction process was optimized by response surface methodology.The experimental results showed that the optimal extraction process parameters were ethanol concentration of 80%,liquid-to-solid ratio of 15:1,extraction time of 60 min,ultrasonic power of 300 W,and extraction temperature of 40℃.The highest was 11.82±0.09 mg/g,followed by the total flavonoid content of daylily from Shaanxi and Gansu,11.42±0.02 and 10.81±0.06 mg/g,respectively,and the lowest total flavonoid content of daylily from Hunan,10.34±0.07 mg/g g.(2)Structural characterization and composition analysis of total flavonoids of Daylily from different origins.Scanning electron microscopy(SEM)was used to analyze the apparent structure of the extracts of daylily from different origins,and the results showed that there was no significant difference between the extracts of daylily from different origins.The characteristic functional groups were analyzed,and the same components in the extracts of daylily from different origins were determined to be flavonoids.Ding,naringenin,astragaloside,hypericin,quercitrin,guavaside,quercetin and cattail glycosides had the highest contents,while the highest contents of kaempferol and luteolin were found in daylily from Shaanxi.(3)Determination of antioxidant activity in vitro of total flavonoids of daylily from different origins.The experimental results showed that the scavenging activities of the total flavonoids of daylily on DPPH,ABTS,·OH and iron reducing power were dose-dependent with the increase of the concentration of total flavonoids of daylily from the four producing areas.At the same concentration,the total flavonoids of daylily from Ningxia have the strongest scavenging ability to DPPH free radicals and·OH free radicals,followed by the scavenging effect of total flavonoids of daylily from Shaanxi and Hunan,and the scavenging ability of total flavonoids from daylily from Gansu;The iron-reducing power and scavenging power of total flavonoids of daylily from Shaanxi are stronger than those from Gansu and Hunan.(4)Effects of total flavonoids of daylily from different origins on oxidative stress injury in HepG2 cells.By measuring intracellular reactive oxygen species(ROS)levels,malondialdehyde(MDA)levels,antioxidant enzymes(SOD,CAT,GPX)content,reduced glutathione(GSH)content,reduced glutathione and oxidation The ratio of glutathione to glutathione(GSH/GSSG)was used to explore the effect of total flavonoids of daylily on oxidative stress injury in HepG2 cells;the antioxidant-related gene SOD1 was quantitatively analyzed by real-time fluorescence quantitative PCR technology.The experimental results showed that the total flavonoids of daylily from the four origins significantly reduced the content of ROS and MDA in the cells induced by H2O2,increased the content of GSH,increased the ratio of GSH/GSSG,and significantly increased the activity level of antioxidant enzymes,leading to SOD1 and so on.The expression of antioxidant genes was up-regulated,indicating that the total flavonoids of daylily from the four origins had a protective effect on H2O2-induced cell oxidative damage.Among them,the expression of SOD1 and other antioxidant genes in the total flavonoids of daylily from Ningxia was the highest.Protective effect of total flavonoids against oxidative stress injury in HepG2 cells. |
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