| Summary: | 碩士 === 實踐大學 === 食品營養研究所 === 92 === Reactive oxygen species (ROS) with high oxidative reactivity can oxidize lipids, proteins, and DNA molecules and consequently lead to cellular and organic injury. We examined the possible mechanisms of ROS on oil smoke induced lung injury and excess metal ion induced atherosclerosis. We evaluated the antioxidant activity and the prevention role of two natural extracts, catechins and soluble fiber, on oil smoke induced lung injury and FeCl3 induced arterial atherosclerosis. Our in vitro results found that both catechins and soluble fiber are efficient antioxidants to scavenge O2─•, H2O2, and HOCl. When compared to vitamin C, the antioxidant ability is in an order of catechins＞vitamin C＞soluble fiber. In the first experiment, we found that the amount of whole blood ROS measured by a chemiluminescence analyzer was increased (320.8±154.8 counts/10sec) after 30 min of exposure to oil smoke. The enhanced ROS level was still maintained at a similar value after 60-120 min of oil smoke exposure. Dietary catechins significantly reduced oil smoke enhanced whole blood ROS (76.0±15.5 counts/10sec) and lung larvage ROS (157.4±10.9 counts/10sec). The protective mechanism by catechins could be due to upregulation of protective Bcl-2 and HSP-70 protein and downregulation of proapoptotic Bax protein expression in the lung. In the second experiment, we evaluated the effect of soluble fiber on on blood lipid profile and FeCl3 induced arterial atherosclerosis in high fat-diet fed hamsters. We found that high fat-diet increased plasmas total cholesterol (from 72.9±2.8 to 110.5±7.1 mg/dl) and low-density lipid protein levels (from 18.5±1.3 to 39.3±5.7 mg/dl) and accelerated the atherosclerotic formation (from 342.0±58.4 to 287.0±17.5 sec). Dietary soluble fiber decreased total cholesterol and low-density lipid proteins and elongated the time for arterial atherosclerosis (from 287.0±17.5 to 378.8±34.6 sec). By western blot, the increased Bax protein and decreased Bcl-2 and HSP-70 protein expression was found in the liver and kidney of high fat-diet fed hamsters. However, soluble fiber decreased Bax expression and increased Bcl-2 and HSP-70 protein expression. Based on the results, we conclude that dietary catechins or soluble fiber can increase antioxidant protein expression and thus decrease oxidative stress induced lung injury and atherosclerosis.
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