Sameuramide A (1), a new cyclic depsipeptide encompassing one each of alanine, N-methyl alanine, N-methyl dehydroalanine, N,O-dimethyl threonine, phenyllactic acid, three β-hydroxy leucines, and two propionates, was isolated from a didemnid ascidian collected at the northern part of Japan. The planar structure was established based on the interpretation of MS and NMR data. The absolute configuration of the subunits was determined by the advanced Marfey’s method and the chiral LC-MS analysis. Compound 1 exhibited the activity of maintaining colony formation of murine embryonic stem (mES) cells without leukemia inhibitory factor (LIF). Down regulation of the gene expression of Krüppel-like transcription factor 4 (Klf4) indicated that 1 itself was not able to maintain the undifferentiated state of the mES cells. However, the expression levels of the marker genes (Nestin, T, Sox17) for three germ layers were upregulated in embryoid bodies (EBs) after treatment of 1 together with LIF, suggesting that 1 plays a supportive role for LIF in maintaining the multipotency of mES cells.

Sameuramide A（1）是一种新的环状缩肽，包含丙氨酸，N-甲基丙氨酸，N-甲基脱氢丙氨酸，N，O-二甲基苏氨酸，苯基乳酸，三个β-羟基亮氨酸和两个丙酸之一。 Didemnid的海鞘收集在日本北部。基于对MS和NMR数据的解释，建立了平面结构。亚基的绝对构型由先进的Marfey方法和手性LC-MS分析确定。化合物1表现出维持鼠胚胎干（mES）细胞无白血病抑制因子（LIF）的集落形成的活性。Krüppel样转录因子4（Klf4）的基因表达的下调表明1本身不能维持mES细胞的未分化状态。然而，与LIF一起处理1后，胚状体（EB）中三个胚层的标记基因（Nestin，T，Sox17）的表达水平上调，表明1在维持LIF的多能性中起LIF的支持作用。 mES细胞。