Study On The Antioxidant Activity Of Lotus Leaf

The lotus leaf is widely used as an inexpensive source for medicine and food. It possesses many biological activities as antioxidant, reducing blood lipid and other pharmacological properties. At present, the lotus leaf is primarily used in the form of herbal raw materials, and explored less in deep processing. In order to fully make use of the lotus leaf, its antioxidant activity in our experiment was studied, which will found for the development of healthy food.In this paper, lotus leaf antioxidant activity was studied by using the biological-activity of tracing method to determine their antioxidant effective fraction. Four extraction methods were compared to optimize extraction process of its antioxidant active substance. The effective parts were processed by acid hydrolysis to further enhance the oxidation activity, and by in vitro simulation artificial gastrointestinal environment to explore the changing tendency of lotus leaf in a follow-up antioxidant activity experiment in vivo and increasing success rate in vivo test. The main results are as follows.1. Through a biologically active tracking method, the polar gradually increasing solvents, such as hexane, ethyl acetate, butanol, were used to extract lotus leaf in turn in order to get different polar parts. Meanwhile, every fractions and crude extracts were evaluated by various antioxidant activity methods. The results showed that leaf had obviously antioxidant activity, and antioxidant active substances mainly concentrated in the ethyl acetate fraction. So, this part was its effective parts for antioxidant activity.2. Compared with the antioxidant activity materials of lotus leaf extracted by water bath percussion, ultrasonic assisted, microwave assisted, and ultrasonic-microwave extraction methods, the optimal extraction method was determined in terms of FRAP values、total antioxidant capacity、scavenging ability of DPPH free radical、scavenging ability of superoxide. The results showed that the capacity of the antioxidant material extracted by ultrasonic and microwave assisted was the strongest, and the extraction efficiency was higher.3. After the antioxidant activity of ethyl acetate fraction was handled by acid hydrolysis, we found that some antioxidant actives such as the total antioxidant capacity, FRAP values, scavenging ability of DPPH free radical, scavenging ability of hydroxyl free radical, scavenging ability of superoxide anion scavenging could be further improved. 4. After the lotus leaf effective parts were treated by using in vitro artificial gastric fluid simulation of in vivo gastric/intestinal environment, we found that the effective parts in simulated in vivo gastric environment (FRAP values, total antioxidant capacity, total reducing powers) were enhanced, the antioxidant activities in vivo intestinal environment (scavenging ability of DPPH free radical, scavenging ability of hydroxyl free radical, scavenging ability of superoxide anion scavenging) were weakened.