Analysis Of Carotenoids In Watermelon And Scavenging Action Of Watermelon Juices On Hydroxyl Radical

The dissertation studied on the isolation methods of the carotenoids from marigold, Gou Qi Zi and spinach and established the separation conditions of the carotenoeds by thin layer chromatography. The stationary phase was silica gel, and the developing solvents were petroleum ether : acetone : methanol=75 : 20 : 5(v : v) for marigold, petroleum ether : acetone=10 : 3(v : v) for Gou Qi Zi, and petroleum ether : iso-propanol : water=100:12 : 0.25(v : v) for spinach. The carotenoids may be separated very well in 16-18cm developing distance. The analytical results from TLC, high performance liquid chromatography(HPLC), and spectrum scanning showed that lutein, zeaxanthin and violaxanthin could be prepared as standards through silica gel thin layer chromatography.The carotenoids in watermelon were investigated using high performance liquid chromatography. The experiments compared six different mobile phases. The results showed that carotenoids were separated more effectively with the mobile phase acetonitrile(ACN) : methanol(MEOH) : dichloromethane(DCM)= 75 : 20 : 5(v : v) using Vydac 201 TP54 C18 chromatographic column at the flow rate 1 ml/min and 450nm wavelength under room temperature. The preliminarily qualitative analysis showed that more than 7 carotenoids were detected in the watermelon. The contents of the carotenoids in the watermelon were determined by the external-standard method.Hydroxyl radical produced in Fenton reaction can be determined indirecrly by measuring the absorbance changes (ΔA ) of methyl violet spectrophotometrically in the system. The scavenging ability of watermelon juices on hydroxyl radical was investigated using this method. The results show that watermelon juices have excellent scavenging action on hydroxyl radical. The scavenging activities of watermelon juices with different flesh colors are S_red > S_peachblow > S₍yellow > S_white. The water phase of watermelon juice exhibits a primary scavenging action and the ether phase almost has no deoxidization ability by comparing the scavenging ability of...