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思文霉素（Ｓｉｗｅｎｍｙｃｉｎ）是最先从我国土壤中的链霉菌培养物中提取的一个新型蒽环类抗生素。研究表明该药是ＤＮＡ拓扑异构酶抑制剂。以ＡＴＰ依赖性ｐＢＲ３２２ＤＮＡ断裂松弛反应，观察思文霉素对从哺乳动物细胞中提取的ＤＮＡ拓扑异构酶ＩＩ活性的抑制作用后发现该药对此酶的最大抑制浓度为２５ｍｍｏｌ／Ｌ。用思文霉素处理Ｂｅｌ７４０２细胞后，从中提取的ＤＮＡ拓扑异构酶ＩＩ所介导的ＤＮＡ断裂松驰反应活性比对照组增加５倍。研究还发现，思文霉素可抑制胞外ＤＮＡ拓扑异构酶Ｉ活性。碱性洗脱实验证明该药可引起ＤＮＡ单链断裂。
Siwenmycin is the first anthracycline antibiotic to be extracted from Streptomyces cultures in our soil. Studies show that the drug is a DNA topoisomerase inhibitor. ATP-dependent pBR322DNA cleavage relaxation reaction observed sphincter of DNA extraction from mammalian cells topoisomerase II activity inhibition found that the maximum inhibitory concentration of the drug on this enzyme was 25mmol / L. After treatment of Bel7402 cells with strychnine, DNA topoisomerase II-mediated DNA strand break relaxation reactivity increased by 5-fold compared with the control group. The study also found that Strychnine can inhibit extracellular DNA topoisomerase I activity. Alkaline elution experiments show that the drug can cause DNA single-strand breaks.