Cinnamophilin as a novel antiperoxidative cytoprotectant and free radical scavenger

The antioxidant properties of cinnamophilin were evaluated by studying its ability to react with relevant reactive oxygen species, and its protective effect on cultured cells and biomacromolecules under oxidative stress. Cinn amophilin concentration-dependently suppressed nonenzymatic iron-induced li pid peroxidation in rat brain homogenates with an IC50 value of 8.0 +/- 0.7 muM and iron ion/ADP/ascorbate-initiated rat liver mitochondrial lipid per oxidation with an IC50 value of 17.7 +/- 0.2 muM. It also exerted an inhibi tory activity on NADPH-dependent microsomal lipid peroxidation with an IC50 value of 3.4 +/- 0.1 muM without affecting microsomal electron transport o f NADPH-cytochrome P-450 reductase. Both 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azo-bis(2-amidinopropane) dihydrochloride-derived peroxyl radical test s demonstrated that cinnamophilin possessed marked free radical scavenging capacity. Cinnamophilin significantly protected cultured rat aortic smooth muscle cells (A7r5) against alloxan/iron ion/H2O2-induced damage resulting in cytoplasmic membranous disturbance and mitochondrial potential decay, By the way, cinnamophilin inhibited copper-catalyzed oxidation of human low-d ensity lipoprotein, as measured by fluorescence intensity and thiobarbituri c acid-reactive substance formation in a concentration-dependent manner. On the other hand, it was reactive toward superoxide anions generated by the xanthine/xanthine oxidase system and the aortic segment from aged spontaneo usly hypertensive rat. Furthermore, cinnamophilin exerted a divergent effec t on the respiratory burst of human neutrophil by different stimulators. Ou r results show that cinnamophilin acts as a novel antioxidant and cytoprote ctant against oxidative damage. (C) 2001 Elsevier Science B.V. All rights r eserved.