Albumin stabilizes (-)-epigallocatechin gallate in human serum: binding capacity and antioxidant property.
(-)-Epigallocatechin gallate (EGCg) is the major component of green tea and is known to show strong biological activity, although it can be easily oxidized under physiological conditions. In this study, we indicate that EGCg is stable in human serum and that human serum albumin (HSA) stabilizes EGCg under aerobic condition. Although EGCg is usually decomposed within 1 h in aqueous solution at neutral pH, EGCg in serum and phosphate buffer (pH 7.4) containing HSA was stable over 1 h, even at neutral and slightly alkaline pH. Under these conditions, EGCg binds to HSA non-covalently. The sulfhydryl group acts as an antioxidant for EGCg oxidation. Incubation of EGCg with HSA is accompanied by the oxidation of a free sulfhydryl group in HSA. These results suggest that the antioxidant property and the binding capacity of HSA contribute to the stabilization of EGCg in human serum.
Department of Food and Nutritional Sciences, and Global COE Program, University of Shizuoka, Shizuoka, Japan.
Min-Jung
MJ
Bae
Takeshi
T
Ishii
Kanako
K
Minoda
Yukiko
Y
Kawada
Tatsuya
T
Ichikawa
Taiki
T
Mori
Miya
M
Kamihira
Tsutomu
T
Nakayama
D002392:Catechin / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry; D004355:Drug Stability; D006801:Humans; D011485:Protein Binding; D012709:Serum Albumin / Q000502:physiology*; D013438:Sulfhydryl Compounds / Q000494:pharmacology
D012709:Serum Albumin; D013438:Sulfhydryl Compounds; D002392:Catechin; C045651:epigallocatechin gallate