Elimination Of Acetaldehyde And Antioxidation Of Intracellular Environment By L-Cysteine

Acetaldehyde (Ace) is harmful metabolites of smoking and drinking. This research initially identified the possible injury mechanism on A549 cell damaged by Ace and the possible protect mechanism of L-Cysteine (L-Cys) pretreatment on A549 cell by analyzing the oxidative damage indicators, morphology and gene expression.In order to observe the protective effects of Ace on A549 cells oxidant/antioxidant system by L-Cys treated A549 cells, methyl thiazolyl tetrazolium (MTT) colorimetric assays for cell viability, ELISA for lactate dehydregenase (LDH) leakage, nitrate reductase assay for Nitric Oxide (NO), thiobarbituric acid method for malondialdehyde (MDA), WST-1 determination for superoxide dismutase (SOD) activity, dithiodimorpholine nitrobenzoic acid colorimetric determination for glutathione perpxidase (GSH-PX) activity were performed. The mitochondrial damage by Ace on A549 as well as L-Cys protective mechanisms were analyzed by PCR for detection of mRNA expression of cytochrome C oxidase subunit Ⅱ (CO Ⅱ), and scanning electron microscopy (SEM), DAPI fluorescence staining and flow cytometry checked the cell cycle and cell apoptosis.The results showed that Ace caused oxidative damage of A549 cells, increased the release of LDH, NO and MDA, but reduced the SOD and GSH-PX activity compared with the control group, the differences were statistically significant (P<0.05); with L-Cys protection groups LDH, NO and MDA were lower than Ace group (200μmol/L), SOD and GSH-PX activity were obvious (P<0.05) higher than Ace group in a dose dependent manners. The gene expression of cytochrome C oxidase subunit Ⅱ(CO Ⅱ) in Ace group was significantly lower compared with control group, while the L-Cys protection groups improved the Ace caused damages; SEM observation, DAPI staining and flow cytometry also showed that L-Cys could effectively improve the oxidative damage on A549 cells by Ace, and reduce the rate of apoptosis.In conclusions, the protective effects of L-Cys on A549 cells against oxidative damage by Ace were in a dose dependent manner within the range of 10-160μmol/L, Ace damaged the mitochondria, caused the release of cytochrome C and apoptosis of A549 cells by free radicals (ROS) arised from Ace, but L-Cys decreased the release of cytochrome C from mitochondria, reduced the rate of apoptosis and protect cell by inhibition of oxidative stress and free radicals.