Gilvocarcin-type polyketide glycosides represent some of the most powerful antitumor therapeutics. Bioactivity-guided fractionation of a culture extract of Streptomyces polyformus sp. nov. (YIM 33176) yielded the known gilvocarcin V (2) and a novel related compound, polycarcin V (1). Structure elucidation by NMR and chemical derivatization revealed that the congener (1) features a C-glycosidically linked α-L-rhamnopyranosyl moiety in lieu of the D-fucofuranose. The concomitant production of two distinct furanosyl and pyranosyl C-glycosides that share the same aglycone is unprecedented in bacteria. A conversion of both isoforms via a quinone methide intermediate can be ruled out, thus pointing to two individual C-glycosylation pathways. Cytotoxicity profiling of polycarcin V in a panel of 37 tumor cell lines indicated significant antitumoral activity with a pronounced selectivity for non-small-cell lung cancer, breast cancer and melanoma cells. As the antiproliferative fingerprint is identical to that of actinomycin D, the known DNA interaction of gilvocarcins was established as a general principle of antitumorigenic activity.
吉尔沃霉素类多酮苷是一些最强大的抗肿瘤治疗药物。在
生物活性的指导下,对多形链霉菌新种(YIM 33176)的培养
提取物进行分馏,得到了已知的吉尔沃霉素 V(2)和一种新型相关化合物多霉素 V(1)。通过核磁共振和
化学衍生法进行的结构阐释显示,同系物(1)的特点是以 C-糖苷键连接的 α-L-rhamnopyranosyl 分子取代了 D-岩
呋喃糖。同时产生两种不同的
呋喃糖基和
吡喃糖基 C-糖苷,并具有相同的苷元,这在细菌中是前所未有的。可以排除这两种异构体通过醌甲苷中间体进行转化的可能性,因此指向两种不同的 C-糖基化途径。聚卡素 V 在 37 种肿瘤
细胞系中的细胞毒性分析表明,它具有显著的抗肿瘤活性,对非小细胞肺癌、乳腺癌和
黑色素瘤细胞有明显的选择性。由于其抗增殖指纹与
放线菌素 D 的指纹相同,因此吉尔伐霉素的已知 DNA 相互作用被确定为抗肿瘤活性的一般原则。