Bufadienolides are a class of natural cardiotonic steroids and are well known for their antitumor activities. Their clinical use has been hindered by poor water solubility. Enzymatic glycosylation is a favorable approach to improve the solubility of natural products. In this work, we describe the highly efficient one‐step synthesis of bufadienolide O‐glucosides and O‐galactosides using a microbial glycosyltransferase YjiC1, with conversion rates from 63% to 99%. Altogether 24 glycosides including 17 new compounds were obtained from 14 substrates, and their structures were identified by extensive NMR and high‐resolution electrospray ionization mass spectrometry (HR‐ESI‐MS) analyses. These products belong to five types: glycosylation at 3β‐OH, 7β‐OH, 3β,7β‐di‐OH, 11α‐OH, and 12β‐OH. The C‐7β or C‐11α O‐glycosides of bufadienolide are reported for the first time. Moreover, the 3‐O‐glycosides exhibited significant cytotoxic activities against A549 and MCF7 human cancer cell lines, and showed potent inhibitory activities against Na⁺/K⁺‐ATPase with IC₅₀ values in the range 0.053–0.76 μM. In particular, bufalin 3‐O‐β‐d‐glucoside showed enhanced water solubility (25‐fold increase from bufalin) and potent antitumor activities (30% inhibition rate, 1.4 mg kg⁻¹, i.p.) on A549 human lung cancer xenograft Balb/c nude mice model, and could be a promising drug candidate.

中文翻译：

---

使用微生物糖基转移酶酶促合成丁二酸内酯O-糖苷作为有效的抗肿瘤药

丁二烯内酯是一类天然的强心类固醇，以其抗肿瘤活性而闻名。不良的水溶性阻碍了它们的临床应用。酶促糖基化是改善天然产物的溶解度的有利方法。在这项工作中，我们描述了高效的一步法合成布法地那利O-葡萄糖苷和O-半乳糖苷使用微生物糖基转移酶YjiC1，转化率从63％到99％。从14种底物中获得了总共24种糖苷，包括17种新化合物，并通过广泛的NMR和高分辨率电喷雾电离质谱（HR-ESI-MS）分析鉴定了它们的结构。这些产物属于五种类型：3β-OH，7β-OH，3β，7β-di-OH，11α-OH和12β-OH的糖基化。的C-7β或C-11α Ö bufadienolide的-glycosides报道首次。此外，3- O-糖苷对A549和MCF7人癌细胞系表现出显着的细胞毒活性，并显示出对Na ⁺ / K ⁺ -ATPase的有效抑制活性（IC _50）值在0.053-0.76μM范围内。特别是，bufalin 3‐ O‐ β‐ d‐葡萄糖苷对A549人肺癌异种移植物显示出更高的水溶性（比bufalin增加25倍）和有效的抗肿瘤活性（30％抑制率，1.4 mg kg ^-1，ip。）。 Balb / c裸鼠模型，可能是有前途的候选药物。