title: A fluorometric assay to determine antioxidant activity of both hydrophilic and lipophilic components in plant foods.
abstract: This study aimed to develop a fluorometric method to determine total antioxidant activity of plant foods. The antioxidant activities in plant foods were determined after extracting (1) hydrophilic components with acidified methanol (methanol:glacial acetate acid:water=50:3.7:46.3), (2) lipophilic components with methanol followed by tetrahydrofuran (THF), or (3) both hydrophilic and lipophilic components using sequential extraction of acidified methanol and THF together. Both the hydrophilic assay [using the hydrophilic radical initiator 2,2'-azobis-(2-amidinopropane)dihydrochloride (10 mmol/L) and hydrophilic probe 2,7-dichlorodihydrofluorescein (DCFH)] and the lipophilic assay [using the lipophilic radical initiator [2,2'-azobis (4-methoxiy-2,4-dimethylvaleronitrile), 2 mmol/L], and the lipophilic probe 4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-undecanoic acid (C11-BODIPY 581/591) (BODIPY: 2 micromol/L)] were used to measure antioxidant activity. The inhibition of BODIPY oxidation was significantly increased (P<.01) when both the hydrophilic and lipophilic components were extracted using acidified methanol and organic solvent as compared to those extracted by organic solvent alone. In addition, the rate of DCFH oxidation was significantly delayed (P<.05) when both components coexisted compared to DCFH oxidation of the hydrophilic component alone. The combination of lipophilic and hydrophilic components in these plant foods showed significantly greater antioxidant activity than that of either hydrophilic or lipophilic component alone. Thus, both hydrophilic and lipophilic components in plant foods and their interactions should be considered when determining their antioxidant activity.
authors.affiliation: Medical College of Qingdao University, Shandong Province, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.forename: C-Y Oliver
authors.initials: CY
authors.lastname: Chen
authors.forename: Hye-Kyung
authors.initials: HK
authors.lastname: Chun
authors.forename: Soo-Muk
authors.initials: SM
authors.lastname: Cho
authors.forename: Ki-Moon
authors.initials: KM
authors.lastname: Park
authors.forename: Yang Cha
authors.initials: YC
authors.lastname: Lee-Kim
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Blumberg
authors.forename: Robert M
authors.initials: RM
authors.lastname: Russell
authors.forename: Kyung-Jin
authors.initials: KJ
authors.lastname: Yeum
mesh_terms: D000578:Amidines / Q000737:chemistry; D029969:Angelica / Q000737:chemistry; D000975:Antioxidants / Q000032:analysis*; D001391:Azo Compounds / Q000737:chemistry; D001896:Boron Compounds; D005591:Chemical Fractionation; D005452:Fluoresceins / Q000737:chemistry; D005470:Fluorometry / Q000379:methods*; D009570:Nitriles / Q000737:chemistry; D010084:Oxidation-Reduction; D031343:Perilla / Q000737:chemistry; D010944:Plants / Q000737:chemistry*; D012995:Solubility; D014675:Vegetables / Q000737:chemistry
chemical_list: D000578:Amidines; D000975:Antioxidants; D001391:Azo Compounds; D001896:Boron Compounds; C120421:C11-BODIPY(581-591); D005452:Fluoresceins; D009570:Nitriles; C065013:2',7'-dichlorodihydrofluorescein; C109522:V 70; C046728:2,2'-azobis(2-amidinopropane)