微球菌属海洋厌氧菌培养物的紫外吸收光谱引导分离，得到一种新的环状六肽，Bulbiferamide（1）。NMR光谱和质谱分析揭示1的结构为一个环状四肽附加一个脲桥接的两个氨基酸单位。值得注意的是，色氨酸是一个连接氨基酸残基，在一方面形成非常罕见的N-氨基酸化吲哚链以便环化，在另一方面连接含脲的尾结构，这是一种前所未有的肽构型方式。组分氨基酸通过先进的Marfey法被确定为L。化合物1对Trypanosoma cruzi表皮质体的生长有抑制作用，其IC50值为4.1μM，与当前批准的药物苯硝唑相当，而在100μM下，它对P388小鼠白血病细胞没有细胞毒性。

UV absorption spectroscopy-guided fractionation of the culture extract of a marine obligate bacterium of the genus Microbulbifer yielded a novel cyclic hexapeptide, bulbiferamide (1). NMR spectroscopic and mass spectrometric analyses revealed the structure of 1 to be a cyclic tetrapeptide appending a ureido-bridged two amino acid unit. Notably, Trp is a junction residue, forming on one hand a very rare N-aminoacylated indole linkage for cyclization and on the other hand connecting the ureido-containing tail structure, which is an unprecedented way of configuring peptides. The component amino acids were determined to be l by the advanced Marfey's method. Compound 1 displayed growth inhibitory activity against Trypanosoma cruzi epimastigotes with an IC50 value of 4.1 μM, comparable to the currently approved drug benznidazole, while it was not cytotoxic to P388 murine leukemia cells at 100 μM.