Isolation And Antioxidant Capacity Of α-farnesene And Total Flavonoids From Apple Skins

Apple is one of the most popular fruit, and is of abundant secondarymetabolites. Flavonoids and α-farnesene are two kinds of the most importantsecondary metabolites, which correlated with fruit quality, storage disorder,and insect attraction. The techniques of isolation and determination of α-farnesene andflavonoids of 'Whitepearmain'Apple, and the DPPH free radical scavengingcapacities of extracts from apple skin, flavonoids isolated from fruit, andexogenous antioxidants were studied .The results were as followed: 1. The primary isolation technique of α-farnesene from apples wasobtained, which was of potential to be used to continue to study the biologicaleffect of α-farnesene. 2. The methods of α-farnesene measurement were improved. The contentof α-farnesene in apple was determined and compared by high performanceliquid chromatography (HPLC) methods and by traditional UV 3李 红 苹果果皮中 a-法尼烯和类黄酮的提取及其抗氧化能力研究spectrophotometric method, respectively. The HPLC method was moreaccurate than UV spectrum method. There were some factors that affects theresult by UV method: There were other compounds which also have absorbedat 232nm in measurement, and there was also an higher absorption of 210nm,which may disturb or make higher of the absorb peak of a-farnesene at 232nm. 3. The optimization of isolation method of total flavonoids from appleskin was obtained by using orthogonal test design, and the content of totalflavonoids was determined. The result showed that 65℃ of water-bathtemperature, 1:20 of ratio of solid to ethanol solution, and two-hour extractiontime were the optimal conditions under which total flavonoids in apple skinwas 3.66%. The content of flavonoids of apple shade and sun-exposed sidewere analyzed and compared. The shade-side apple skin has lower levelflavonoids than the sun-exposed skin. 4. The 2,2-diphenyl-1-picrylhydrazyl (DPPH ·) radical scavengingcapacity of total flavonoids, water-soluble and lipid soluble compoundsisolated from apple with different treatments was determined. Extracts ofapple had strong antioxidant activity and scavenging DPPH· free radicalability which meant that apple was of the ability of scavenging hydroxyl freeradical, superoxide anion and alkyl free radical, and interrupting the reactionchain of LDL peroxidation. Antioxidant activity of the water-soluble extractwas stronger than that of lipid soluble, suggesting that there were antioxidantswith different polarity in apple. The radical scavenging ability of sun-exposedside of apple was stronger than shade side. 5. Exogenous antioxidants were also used to test the ability of scavengingDPPH· free radical. Rutin and Quercetin had strong capacity of scavenging 4山东农业大学硕士研究生毕业论文DPPH· free radical. But Quercetin's capacity was stronger than that of Rutin.DPA, which was an antioxidant used traditionally to control superficial scaldand also had the ability of scavenging DPPH·free radical .