Abstract: Generation of reactive oxygen species plays a pivotal role in the development of cardiovascular diseases. The present study describes the effects of the methanolic extract of Phoebe grandis (MPG) stem bark on reactive oxygen species-induced endothelial dysfunction in vitro. Endothelium-dependent (acetylcholine, ACh) and -independent relaxation (sodium nitroprusside, SNP) was investigated from isolated rat aorta of Sprague-Dawley (SD) in the presence of the β-NADH (enzymatic superoxide inducer) and MPG extract. Superoxide anion production in aortic vessels was measured by lucigen chemiluminesence. Thirty minutes incubation of the rat aorta in vitro with β-NADH increased superoxide radical production and significantly inhibited ACh-induced relaxations. Pretreatment with MPG (0.5, 5 and 50 μg/mL) restored the ACh-induced relaxations (Rmax: 92.29% ± 2.93, 91.02% ± 4.54 and 88.31 ± 2.36, respectively) in the presence of β-NADH. MPG was ineffective in reversing the impaired ACh-induced relaxations caused by pyrogallol, a non-enzymatic superoxide generator. Superoxide dismutase (a superoxide scavenger), however, reversed the impaired ACh relaxations induced by both β-NADH and pyrogallol. MPG also markedly inhibited the β-NADH-induced generation of the superoxide radicals. Furthermore, MPG scavenging peroxyl radicals generated by tBuOOH (10−4 M).These results indicate that MPG may improve the endothelium dependent relaxations to ACh through its scavenging activity as well as by inhibiting the NADH/NADPH oxidase induced generation of superoxide anions.
Keywords: Phoebe grandis; β-NADH; isolated rat aorta; endothelial dysfunction; superoxide anions
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Yeh-Siang, L.; Subramaniam, G.; Hadi, A.H.A.; Murugan, D.; Mustafa, M.R. Reactive Oxygen Species-Induced Impairment of Endothelium-Dependent Relaxations in Rat Aortic Rings: Protection by Methanolic Extracts of Phoebe grandis. Molecules 2011, 16, 2990-3000.
Yeh-Siang L, Subramaniam G, Hadi AHA, Murugan D, Mustafa MR. Reactive Oxygen Species-Induced Impairment of Endothelium-Dependent Relaxations in Rat Aortic Rings: Protection by Methanolic Extracts of Phoebe grandis. Molecules. 2011; 16(4):2990-3000.
Yeh-Siang, Lau; Subramaniam, Gopal; Hadi, A. Hamid A.; Murugan, Dharmani; Mustafa, Mohd Rais. 2011. "Reactive Oxygen Species-Induced Impairment of Endothelium-Dependent Relaxations in Rat Aortic Rings: Protection by Methanolic Extracts of Phoebe grandis." Molecules 16, no. 4: 2990-3000.