The main purpose of the present study was to investigate the ability of ethyl acetate fraction (EAF) from Ephedra fragilis to function as a protective agent against hydrogen peroxide induced oxidative damage in Tetrahymena pyriformis. The cells were preincubated with EAF (50-200 μg/mL) or ascorbic acid (50 μg/mL) for 24 h, followed by incubation with 50% H₂O₂ inhibitory concentration for 48 h. Cell viability was assessed using trypan exclusion method. Cell morphology and mobility, antioxidant enzymes activities (catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR)), malondialdehyde (MDA) and protein carbonyl (PCO) levels, DNA fragmentation and metabolic enzymes activities (succinate dehydrogenase (SDH) and NADPH-cytochrome c reductase (NCCR)) were investigated. Our results indicate that, pretreatment of T. pyriformis cells with EAF improved the cell viability, restored normal cell mobility and morphology, decreased the levels of both MDA and PCO level, prevent DNA fragmentation and enhanced the activity of antioxidant (CAT, SOD and GR) and metabolic (SDH and NCCR) enzymes in H₂O₂ damaged cells. In conclusion, these results suggest for the first time that E. fragilis is a promising source of natural antioxidants, that could offer protection against oxidative stress and should be further exploited for its use in clinical medicine.

本研究的主要目的是研究脆弱麻黄中的乙酸乙酯级分（EAF）用作抗过氧化氢引起的梨形四膜虫氧化损伤的保护剂的功能。将细胞与EAF（50-200μg/ mL）或抗坏血酸（50μg/ mL）预孵育24 h，然后与50％H ₂ O ₂孵育抑制浓度48小时。使用锥虫排斥法评估细胞活力。细胞形态和迁移率，抗氧化酶活性（过氧化氢酶（CAT），超氧化物歧化酶（SOD）和谷胱甘肽还原酶（GR）），丙二醛（MDA）和蛋白羰基（PCO）水平，DNA片段化和代谢酶活性（琥珀酸脱氢酶（SDH） ）和NADPH-细胞色素C还原酶（NCCR））。我们的结果表明，用电弧炉预处理梨形毛虫细胞可提高细胞活力，恢复正常的细胞迁移率和形态，降低MDA和PCO的水平，防止DNA片段化并增强抗氧化剂的活性（CAT，SOD和GR ）和H ₂ O _2中的代谢酶（SDH和NCCR）受损的细胞。总之，这些结果首次表明脆弱的大肠杆菌是天然抗氧化剂的一种有前途的来源，可以提供抗氧化应激的保护，应进一步用于临床医学。