本论文以6种具有抗氧化活性的药用植物乌头、唐松草、独活、车前草、薄荷、泽泻为材料分离内生菌，并对内生菌发酵液和菌丝体提取物中抗氧化活性成分进行了研究。实验以PDA培养基分离内生真菌，以高氏培养基分离内生放线菌，测定各提取样品的抗氧化活性，比较其总酚含量和总黄酮含量，并结合形态学和分子生物学方法对高活性菌株进行的鉴定。结果分别分离得到43株内生真菌，18株内生放线菌，其中内生真菌显示了较好的抗氧化活性，对?OH自由基有较强清除（清除率≥70%）作用的菌株有6株，占所用菌株的9.84%。其中菌株DHL-10发酵液乙酸乙酯提取物显示了较强的抗氧化活性，对过氧化氢的IC50为0.26 mg/mL，总酚和总黄酮含量分别达到了0.81±0.05 mg/g和0.84±0.05 mg/g；分子生物学鉴定结合形态学鉴定该菌株为链格孢菌属（Alternaria sp）真菌。本研究的结果证明，药用植物内生菌是抗氧化活性物质寻找的良好资源。

Endophytes were isolated from six medicinal plants with antioxidant activity, namely, Aconitum carmichaelii, Thalictrum aquilegifolium Linn., Angelicae pubescentis Radix, Plantago asiatica L., Mentha haplocalyx Briq, and Alisma orientale. The active antioxidant ingredients from the fermentation broth of endophytes and mycelium extract were studied. Potato dextrose agar (PDA) medium and Gauze’s medium were used to isolate the endophytic fungi and endophytic actinomycetes, respectively. The antioxidant activities of all extracts were measured, the total phenolic and total flavonoid content of the extracts from those endophytes were compared, and high-activity strains were identified using morphological and molecular biological methods. Finally, 43 endophytic fungal strains and 18 endophytic actinomycete strains were isolated. Among them, the endophytic fungi had good antioxidant activity, and six strains (9.84%) showed a strong ?OH free radical scavenging capacity (clearance rate ≥70%). The ethyl acetate extract of the fermentation broth of DHL-10 strain showed strong antioxidant activity; its half maximal inhibitory concentration (IC50) value for hydrogen peroxide radical scavenging was 0.26 mg/mL, and total phenolic and flavonoid content were up to 0.81±0.05 mg/g and 0.84±0.05 mg/g, respectively. DHL-10 strain was identified as an Alternaria sp. by morphological and molecular biological methods. Our results demonstrate that the endophytes from medicinal plants are good sources for active antioxidant substances.

国家自然科学基金资助项目(31360379)；甘肃省自然基金资助项目（1308RJZA167）