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NISCAIR ONLINE PERIODICALS REPOSITORY (NOPR) >
NISCAIR PUBLICATIONS >
Research Journals >
Indian Journal of Biochemistry and Biophysics (IJBB) >
IJBB Vol.48 [2011] >
IJBB Vol.48(4) [August 2011] >
| Title: | Free radical reactions of a naturally occurring flavone baicalein and possible mechanisms towards its membrane protective properties |
| Authors: | Adhikari, S
Tilak, Jai C
Devasagayam, T P A |
| Keywords: | Baicalein
Rat liver mitochondria
Rat heart homogenate
Lipid peroxidation
Pulse radiolysis
Hydroxyl radical
Peroxyl radical
Peroxynitrite |
| Issue Date: | Aug-2011 |
| Publisher: | NISCAIR-CSIR, India |
| Abstract: | Baicalein (5, 6, 7-trihydroxy-2-phenyl-4H-1-benzopyran-4-one),
a naturally occurring flavone present in some of the medicinal plants is known
for its potential therapeutic effects, such as cardioprotective, anticancer and
anti-inflammatory properties. However, detailed role and mechanisms behind its
protective properties against different generators for oxidative stress have
not been examined. In the present study, we investigated the possible
protective ability of baicalein against the membrane damage caused by reactive
oxygen species (ROS) and reactive nitrogen species (RNS) and the mechanisms
involved using pulse radiolysis technique.
Baicalein offered efficient
protection even at a concentration of 10  M towards membrane damage caused by lipid peroxidation induced by the
 -radiation, peroxyl radicals, ascorbate-Fe2+ and peroxynitrite in
rat liver mitochondria and heart homogenate. To elucidate its reaction
mechanisms with biologically relevant radicals, transient absorption
spectroscopy employing pulse radiolysis technique was used. Baicalein showed
fairly high rate constants (3.7 × 109, 1.3 × 109 and 8.0 ×
108 dm3 mol-1 s-1 for
hydroxyl, azidyl and alkylchloroperoxyl radicals, respectively), suggesting
that baicalein can act as an effective scavenger of these radicals. In each
case, the phenoxyl radical of baicalein was generated. Thus, it was evident
that the phenolic moiety of baicalein was responsible for the free radical
scavenging process. Baicalein also reacts with linoleic acid peroxyl radical
(LOO·), indicating its ability to act
as a chain breaking antioxidant. Peroxynitrite-mediated radicals were shown to
be reactive towards baicalein and the bimolecular rate constants were 2.5 × 107
and 3 × 108 dm3 mol-1 s-1
for ·NO2 and CO3·- radicals, respectively. In
conclusion, our results revealed the potential of baicalein in protecting
mitochondrial membrane against oxidative damage induced by the four different
agents. We propose that the protective effect is mediated via scavenging of
primary and secondary radicals generated during oxidative stress. |
| Page(s): | 275-282 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-0959 (Online); 0301-1208 (Print) |
| Source: | IJBB Vol.48(4) [August 2011]
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