NADPH- and linoleic acid hydroperoxide-induced lipid peroxidation and destruction of cytochrome P-450 in hepatic microsomes

In this study, we evaluated the ability of Scutellaria baicalensis Georgi to protect lipid-peroxidation (LPO) in lung tissue after free radical-induced injury. We prepared S. baicalensis root (SBR) extracts using different solvents. The total flavonoid and total phenol contents of each extract were measured, and the ROS damage protection was evaluated by analyzing linoleic acid hydroperoxide (LHP)-induced LPO in rat lung mitochondria. Moreover, evaluating diphenylpicrylhydrazyl (DPPH), hydrogen peroxide, superoxide anion radical, and hydroxyl radical scavenging abilities and using metal chelating assays were used to determine in vitro antioxidant activity. The ethyl acetate (EtOAc) extract showed high ROS scavenging ability, and four compounds were subsequently isolated and purified from this extract: baicalin, baicalein, wogonin, and oroxylin A. Baicalein in rat lung mitochondria the most significant LHP-induced LPO inhibition was shown and extracted with EtOAc that contained the highest amount of baicalein. Thus, baicalein and the EtOAc extract of SBR may be efficient in conferring ROS damage protection and inhibiting LHP-induced LPO in rat lung mitochondria. Additional studies are warranted to investigate their use as antioxidant therapy for respiration infections, nutrition supplements, and lead compounds in pharmaceuticals.

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Detection of free radicals produced from the reaction of cytochrome P-450 with linoleic acid hydroperoxide

Biochemical Journal ◽

10.1042/bj3280565 ◽

1997 ◽

Vol 328 (2) ◽

pp. 565-571 ◽

Cited By ~ 37

Author(s):

Cristina ROTA ◽

P. David BARR ◽

V. Martha MARTIN ◽

F. Peter GUENGERICH ◽

Aldo TOMASI ◽

...

Keyword(s):

Linoleic Acid ◽

Peroxyl Radical ◽

Intramolecular Rearrangement ◽

Linoleic Acid Hydroperoxide ◽

Unimolecular Decomposition ◽

Chemical Systems ◽

Esr Spin Trapping ◽

Radical Adduct ◽

Acid Hydroperoxide ◽

Cytochrome P 450

The ESR spin-trapping technique was employed to investigate the reaction of rabbit cytochrome P-450 1A2 (P450) with linoleic acid hydroperoxide. This system was compared with chemical systems where FeSO4 or FeCl3 was used in place of P450. The spin trap 5,5ʹ-dimethyl-1-pyrroline N-oxide (DMPO) was employed to detect and identify radical species. The DMPO adducts of hydroxyl, O2-•, peroxyl, methyl and acyl radicals were detected in the P450 system. The reaction did not require NADPH-cytochrome P-450 reductase or NADPH. The same DMPO-radical adducts were detected in the FeSO4 system. Only DMPO-•OH radical adduct and carbon-centred radical adducts were detected in the FeCl3 system. Peroxyl radical production was completely O2-dependent. We propose that polyunsaturated fatty acids are initially reduced to form alkoxyl radicals, which then undergo intramolecular rearrangement to form epoxyalkyl radicals. Each epoxyalkyl radical reacts with O2, forming a peroxyl radical. Subsequent unimolecular decomposition of this peroxyl radical eliminates O2-• radical.

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