The microbial transformation of podophyllotoxin by endophytic actinomycetes isolated from the rhizoma of Taoerqi ( Sinopodophyllum hexandrum) was investigated to obtain some structural analogues or derivatives of podophyllotoxin. Endophytic actinomycetes were isolated from the rhizoma of S. Hexandrum by surface-sterilization method, and screening test for the microbial transformation of podophyllotoxin was carried out using thin layer chromatography and high performance liquid chromatography ( HPLC ). Bio-transformed products of podophyllotoxin were isolated and purified by silica column chromatography and preparative HPLC, and chemical structures of transformed products were elucidated on the basis of chemical spectral data. The endophytic actinomycetes was identified by morphological characteristics, physiological and biochemical characteristics, and the analysis of fragment of 16S rRNA gene. The results showed that among totally isolated 20 endophytic actinomycetes, one was found to be able transform podophyllotoxin into 4'-demethylepipodophyllotoxin, which was identified preliminarily as Streptomyces sp. Endophytic actinomycetes Streptomyces sp. Was able to modify the chemical structure of podophyllotoxin by demethylation and isomerization reaction, it was deduced that this actinomycetes possessed 0-demethylation and isomerization enzyme.%调查桃儿七根茎内生放线菌对鬼臼毒素的微生物转化,以期获得一些鬼臼毒素的结构类似物或衍生物.利用表面消毒法分离内生放线菌；采用薄层层析和高效液相色谱(HPLC)方法筛选转化鬼臼毒素的内生放线菌；利用硅胶柱层析和制备HPLC分离纯化生物转化产物；应用波谱技术解析转化产物的化学结构；通过形态学、生理生化特征和16S rRNA基因序列分析对内生放线菌进行初步鉴定.从桃儿七根茎中分离出20株内生放线菌,经筛选发现其中1株放线菌能转化鬼臼毒素,其产物为4′-去甲基表鬼臼毒素.初步鉴定该内生放线菌为Streptomyces sp..内生放线菌Streptomyces sp.能对鬼臼毒素进行去甲基和异构化修饰,推测其可能具有O-去甲基化酶和异构化酶.
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