Identification and quantification of antioxidants in Fructus Lycii

Kim Le, Francis Chi Keung Chiu, Kian Fatt Ng

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Fructus lycii was extracted with 95 ethanol and the flavonoid content was determined to be 1.56 mg quercetin-equivalents/g extract. The following antioxidative activities were determined in the extract: (a) radical-scavenging activity (80 ?Emol trolox equivalent antioxidant capacity/g), measured by its ability to scavenge 2,2??-azinobis-3-ethylbenzothiazoline-6-sulfonic acid radical, (b) reducing capacity (301 ?Emol trolox equivalent reducing capacity/g), measured by its ability to directly donate an electron in the reduction of Fe(III) to Fe(II), and (c) chelating activity (2.5 ?Emol ethylenediamine-tetraaceticacid equivalents/g), measured by its ability to remove Fe(II) ion from complexation with ferrozine. Three flavonol species in the extract were identified and quantitated by reversed-phase HPLC and their structures confirmed by electrospray ionization-mass spectroscopy: kaempferol (135 ?Eg/g), quercetin (296 ?Eg/g) and myricetin (247 ?Eg/g). These results showed that F. lycii contains substantial amounts of the three antioxidative activities and is rich in flavonoids. The three flavonols accounted for 43 of total flavonoid content.
Original languageEnglish
Pages (from-to)353 - 363
Number of pages11
JournalFood Chemistry
Issue number1
Publication statusPublished - 2007

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