Study On The Extraction,Preliminary Purification And Antioxidant Activity Of Total Flavonoids Of Iberis Amara Seeds

Flavonoids are widely distributed in seeds, leaves and fruits of plants. Flavonoids have been the focus for studies in Mainland China as well as abroad due to their multiple biological activities such as antioxidant activity, anti-aging effect and anticancer effects. However, only few studies exist on the extraction of total flavonoids from Iberis amara seeds(IA). In this thesis work, IA, obtained from Guangzhou Tianyefeng Park Green Co., Ltd(Guangzhou, China), was used as the raw material. Then extraction, separation, purification and antioxidant activity of IA total flavonoids(IAF) were systematically studied. This study offered not only a reference standard for industrial applications, but it also has a promising prospect and value for widely exploitation and utilization of IAF resources. The main contents and results are as follows:(1) Ultrasonic- assisted extraction(UAE) was adopted to extract IAF, called crude IAF. Then orthogonal experiment and response surface method(RSM) were applied to optimize the extraction process. Grinding particle size was fixed at 60 mesh, the best extraction conditions were obtained as follows: ethanol concentration 83%, ultrasonic time 11 min, liquid-solid ratio 62(mL/g) and ultrasonic power 96 W. Under these conditions, the yield of IAF was 2.568 � 0.05%. The results displayed that the ethanol concentration was the most important factor. In turn it was followed by extraction time, solid-to-liquid ratio and ultrasonic power.(2) Based on the static adsorption and desorption experiment on crude IAF, the X-5 resin was selected as the optimal resin among 6 types of resins. The X-5 resin was performed to optimize the purification process through static and dynamic tests to get purified IAF. The optimal parameters were as follows: sample concentration 1.569 mg/m L, sample amount 30 mL, sample flow rate 1.5 mL/min, sample pH, concentration of ethanol elution 70%, elution volume 100 mL, elution flow rate 1.0 m L/min. Under optimal conditions using the X-5 resin, the purity of IAF increased 8-fold higher from 9.18% to 74.59%. Furthermore, preliminary identification of the purified IAF was done by color reaction and UV spectrum. The main types of flavonoids and flavonols were determined.(3)The antioxidant activity of both crude and purified IAF was investigated. The result of DPPH-scavening capacity and reducing power showed a dose-dependent association between the IAF concentration and antioxidant activity in the studied concentration range. When the purified IAF concentration was beyond 0.4 mg/m L, it showed a higher reducing power than BHT. At the cellular level, the study was used to construct a H2O2-induced cells oxidative injury model. The antioxidant activity of purified IAF was evaluated by cell viability and reactive oxygen species(ROS). The results showed that when purified IAF concentration was between 12.5-50 ?g/m L, it could increase cells viability and partly decrease the amount of ROS. In conclusion, IAF has a strong antioxidant activity and the purified IAF obviously showed better antioxidant activity than crude IAF at the same concentration.