BACKGROUND: In previous investigation, we have identified antioxidative effects of water-soluble ethanolic extracts (named as AKE) from Arenaria kansuensis and inferred that these extracts or their constituents may also have antihypoxic activity. A. kansuensis has been widely used in traditional Tibetan medicine for altitude sickness (AS) and has been known as the herb of anti-inflammatory and hypoxia resistance for a long time.PURPOSE: The purpose of this study is to evaluate protective effects of AKE and its major constituents against hypoxia-induced lethality in mice and RSC96 cells. STUDY DESIGN AND METHODS: Hypoxia-induced lethality in mice was investigated by 3 experimental animal models of hypoxia. Meanwhile, we established a RSC96 cell model of hypoxia which applied to screen and assess the anti-hypoxic activity of compounds isolated from A. kansuensis. RESULTS: Results indicated that AKE dose-dependently prolonged survival time of hypoxia induced lethality in mice compared to vehicle group and exhibited significantly anti-hypoxic effect. AKE also enhanced the number of red blood cells (RBC) and the concentration of hemoglobin (HB). 8 compounds were bio-guided separated and purified from AKE based on the animal model and cell model of hypoxia. Among which pyrocatechol (C16) and tricin 7-O-β-d-glucopyranoside (C13) were confirmed to express better protective effects on cell damage induced by hypoxia, suggesting that these two compounds are major active constituents of AKE for anti-hypoxia. CONCLUSION: This study demonstrated that pyrocatechol and tricin 7-O-β-d-glucopyranoside could be therapeutic candidates for treatment of AS. It is the first time to find the major active constituents of AKE for anti-hypoxia. Meanwhile, a RSC96 cell model of hypoxia was established to screen anti-hypoxic activity of compounds for the first time.