Abstract: The objective of this study was to investigate the content of total phenolics and total flavonoid and free radical scavenging activity of Cremanthodium humile (EECH) as well as its protective effect against hypobaric hypoxia (HH) induced injury on mice.According to the results,the contents of total flavonoid and total phenolics in EECH were 378.35 ± 7.04 mg Ru/g extract and 114.58 ± 0.99 mg GAE/g extract,respectively.EECH showed excellent scavenging effect on DPPH,hydroxyl,nitric oxide radical with the IC₅₀ value of 80.90 ± 0.47,263.54 ± 6.82 and 285.26 ± 4.45 μg/mL,but still weaker than Vc.While EECH exhibited stronger scavenging activity on superoxide than Vc.Administration of EECH can prolong the survival time of mice under normobaric hypoxia,decrease the level of MDA in brain and heart of mice under HH condition and increase the activity of SOD,CAT and GSH-Px.All of these results indicated that EECH could be regarded as an excellent source of natural antioxidants and prevented damage from HH induced brain and heart injury.

Key words: Cremanthodium humile, free radical scavenging, hypobaric hypoxia, antioxidant enzymes