Trolox-equivalent antioxidant capacity and composition of five alpine plant species growing at different elevations on the Qinghai-Tibetan Plateau

Background: Alpine plants on the Qinghai-Tibetan Plateau are exposed to an extremely harsh environment, namely severe cold, strong ultraviolet radiation, hypoxia and low CO2 partial pressure. These conditions are sources of oxidative stress, which increase in severity with increasing elevation.Aims: To examine whether antioxidant capacity and chemical composition of alpine plants change with increasing elevation.Methods: We measured the Trolox-equivalent antioxidant capacity (TEAC) and chemical composition of five alpine plant species at 3016, 3814 and 4621m a.s.l.Results: With increasing elevation: (1) the TEAC increased and total phenols and tannins tended to increase in two forb and two shrub species but not in a sedge species; (2) concentrations of protein and fat increased in all five plant species; (3) polyunsaturated fatty acids (PUFA) increased and (4) mineral concentrations tended to decrease, but trends were inconsistent.Conclusions: We conclude that with increasing elevation, TEAC and total phenols and tannins increased which we interpreted as an adaptation to higher oxidative stress; and protein and fat contents increased to support high metabolic activity. The increase in PUFA and the trend for minerals to decrease with increasing elevation require further investigation.