[formula: see text] Apoptolidin (1) is a novel oncolytic lead that induces apoptosis in transformed cell lines with exceptional selectivity. We report the isolation and characterization of a ring-expanded macrolide isomer of apoptolidin: isoapoptolidin (2). The solution conformation of isoapoptolidin is described. The rate of isomerization was measured under biologically relevant conditions and found to approach equilibrium within the time frame of most cell-based assays. Isoapoptolidin's ability to inhibit mitochondrial F0F1-ATPase is over 10-fold less than that of apoptolidin.

中文翻译：

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异Apooptolidin：Apoptolidin的环扩展异构体的结构和活性。

[公式：参见文本] Apoptolidin（1）是一种新型溶瘤前导物，可以极高的选择性诱导转化细胞株的凋亡。我们报告了凋亡小环素的环膨胀大环内酯异构体的分离和表征：isoapoptolidin（2）。描述了异apoptolidin的溶液构象。在生物学相关条件下测量异构化速率，发现其在大多数基于细胞的测定法的时间范围内趋于平衡。异Apooptolidin抑制线粒体F0F1-ATPase的能力比Apoptolidin低10倍以上。