Abstract
Scavenging rates of cyclodextrin-solubilized lipophilic antioxidants, namely catechin, epicatechin, epigallocatechin gallate, and resveratrol, against alkoxyl (RO â¢) radical were measured with the use of electron paramagnetic resonance (EPR) spin-trapping method. Results indicated that the scavenging rates of catechin and resveratrol were notably dependent on the solubilizer used, i.e., native β-cyclodextrin (β-CD) or heptakis(2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD). But, epicatechin and epigallocatechin gallate showed almost no dependence on the cyclodextrin used. Catechin's scavenging rate in β-CD was 66% lower than in DM-β-CD; in contrast, resveratrol in β-CD showed 45% higher rate than in DM-β-CD. Based on the reported solution-NMR structure of the inclusion complex of these antioxidants, it was concluded that the scavenging rate is decreased when the cyclodextrin cavity preferentially encapsulates the antioxidant-function bearing group, i.e., O- and p-quinolinol group in catechin and resveratrol, respectively. The depth of inclusion of the functional group determines the extent of the scavenging rate difference, suggesting that the cavity wall of the cyclodextrin acts like a barrier that hinders the approach of attacking free radicals.
| Original language | English |
|---|---|
| Pages (from-to) | 598-603 |
| Number of pages | 6 |
| Journal | International Journal of Chemical Kinetics |
| Volume | 44 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - Sep 2012 |
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ASJC Scopus subject areas
- Inorganic Chemistry
- Organic Chemistry
- Physical and Theoretical Chemistry
- Biochemistry
Cite this
Cyclodextrin encapsulation of the functional group diminishes an antioxidant's free radical scavenging rates. / Ishikawa, Misa; Sueishi, Yoshimi; Endo, Nobuyuki; Oowada, Shigeru; Shimmei, Masashi; Fujii, Hirotada; Kotake, Yashige.
In: International Journal of Chemical Kinetics, Vol. 44, No. 9, 09.2012, p. 598-603.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Cyclodextrin encapsulation of the functional group diminishes an antioxidant's free radical scavenging rates
AU - Ishikawa, Misa
AU - Sueishi, Yoshimi
AU - Endo, Nobuyuki
AU - Oowada, Shigeru
AU - Shimmei, Masashi
AU - Fujii, Hirotada
AU - Kotake, Yashige
PY - 2012/9
Y1 - 2012/9
N2 - Scavenging rates of cyclodextrin-solubilized lipophilic antioxidants, namely catechin, epicatechin, epigallocatechin gallate, and resveratrol, against alkoxyl (RO â¢) radical were measured with the use of electron paramagnetic resonance (EPR) spin-trapping method. Results indicated that the scavenging rates of catechin and resveratrol were notably dependent on the solubilizer used, i.e., native β-cyclodextrin (β-CD) or heptakis(2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD). But, epicatechin and epigallocatechin gallate showed almost no dependence on the cyclodextrin used. Catechin's scavenging rate in β-CD was 66% lower than in DM-β-CD; in contrast, resveratrol in β-CD showed 45% higher rate than in DM-β-CD. Based on the reported solution-NMR structure of the inclusion complex of these antioxidants, it was concluded that the scavenging rate is decreased when the cyclodextrin cavity preferentially encapsulates the antioxidant-function bearing group, i.e., O- and p-quinolinol group in catechin and resveratrol, respectively. The depth of inclusion of the functional group determines the extent of the scavenging rate difference, suggesting that the cavity wall of the cyclodextrin acts like a barrier that hinders the approach of attacking free radicals.
AB - Scavenging rates of cyclodextrin-solubilized lipophilic antioxidants, namely catechin, epicatechin, epigallocatechin gallate, and resveratrol, against alkoxyl (RO â¢) radical were measured with the use of electron paramagnetic resonance (EPR) spin-trapping method. Results indicated that the scavenging rates of catechin and resveratrol were notably dependent on the solubilizer used, i.e., native β-cyclodextrin (β-CD) or heptakis(2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD). But, epicatechin and epigallocatechin gallate showed almost no dependence on the cyclodextrin used. Catechin's scavenging rate in β-CD was 66% lower than in DM-β-CD; in contrast, resveratrol in β-CD showed 45% higher rate than in DM-β-CD. Based on the reported solution-NMR structure of the inclusion complex of these antioxidants, it was concluded that the scavenging rate is decreased when the cyclodextrin cavity preferentially encapsulates the antioxidant-function bearing group, i.e., O- and p-quinolinol group in catechin and resveratrol, respectively. The depth of inclusion of the functional group determines the extent of the scavenging rate difference, suggesting that the cavity wall of the cyclodextrin acts like a barrier that hinders the approach of attacking free radicals.
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U2 - 10.1002/kin.20629
DO - 10.1002/kin.20629
M3 - Article
VL - 44
SP - 598
EP - 603
JO - International Journal of Chemical Kinetics
JF - International Journal of Chemical Kinetics
SN - 0538-8066
IS - 9
ER -