Article
J. Agric. Food Chem., Vol. 57, No. 15, 2009 7123
macroscopic property (29). Taken together, the differences in
chemical structures between baicalin and baicalein, the effects of
7-O-glycoside moiety on the conformation of flavones backbone,
and its steric hindrance against oxidative peroxyl radicals may all
account for the difference in the radical scavenging activities
between these two flavonoids.
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In summary, we have systematically investigated the physico-
chemical properties, the radical scavenging, and antilipoxida-
tion activities of baicalin, as well as the kinetics of regenerating
β-Car from β-Car•þ by baicalin. Baicalin as a glycoside-bearing
flavonoid is shown to be lipophilic and very reducing, but it is
of rather low radical scavenging activity and is almost ineffec-
tive in the retardation of AAPH- or AMVN-induced lipid
peroxidation. In homogeneous solution the conjugated bases
of baicalin are found to be capable of regenerating β-Car, whereas
neutral baicalin cannot. The present work has proven that
baicalin by itself shows little antilipoxidation activity; however,
it becomes very effective when combined with β-Car owing to
the synergistic interaction between its conjugated bases and β-Car
in liposomal membrane. The influence of the 7-O-glycoside
moiety on the radical scavenging activities of baicalin has been
discussed with reference to its metabolite baicalein, and the
radical scavenging and antilipoxidation properties of baicalin
have been discussed in terms of its physicochemical properties
and molecular structures.
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ABBREVIATIONS USED
AAPH, 2,20-azobis(2-methylpropionamidine) dihydrochlor-
ide; AMVN, 2,20-azobis(2,4-dimethylvaleronitrile); ABTS, 2,
20-azinobis(3-ethylbenzothiazoline-6-sulfonic acid); β-Car, β-car-
otene; DMSO, dimethyl sulfoxide; TEAC, Trolox equivalent
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L. H. Puerarin as an antioxidant fluorescence probe. Chem. Phys.
Lett. 2008, 452, 253–258.
antioxodation capacity; PC, -R-phosphatidylcholine.
L
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ACKNOWLEDGMENT
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We thank C.-H. Chen and C.-B. An for their support in the LP
experiments. Continuing support from LMC, Centre for Ad-
vanced Food Studies to the Food Chemistry group at University
of Copenhagen, is acknowledged.
Laboratory Manual; Wiley: Chichester, U.K., 1962.
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K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.;
Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.;
Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.;
Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.;
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