Design of new pamamycin derivatives that show aerial mycelium-inducing or growth inhibition activity alone

1.脱N-甲基帕霉素A组分的分离、结构鉴定及生物活性研究在TLC分析中，在Rf0.30处出现一个新的Dragendorff反应阳性斑点。该组分经硅胶柱层析、DS-HPLC和NH_2-HPLC纯化，得到3个新化合物。利用甲硫氨酸-甲基-D_3补料培养制备的标记物，经MS波谱鉴定为去N-甲基帕马菌素。相同烷基排列的去N-甲基帕帕霉素具有较强的气生菌丝诱导活性和较弱的生长抑制活性。2.为了寻找可能的生物合成前体N，N-二甲基帕帕霉素，我们在含有甲基化抑制剂的条件下培养了煤化链霉菌。结果表明，在DL-乙硫氨酸饲料培养的提取物中发现了该物质。进一步研究乙硫氨酸的使用时间和用量将有助于提高产率。3.从链霉菌长烷基侧链菌中分离帕米霉素同系物。据报道，HKI-0118产生了新的具有长烷基侧链的帕帕霉素同系物，但它们尚未实现分离。我们用两个串联的NH_2-HPLC柱成功地分离了这些同系物。

1.Isolation, structure elucidation and biological activity of de-N-methylpamamycins A crude pamamycin fraction showed a new Dragendorff reaction-positive spot at Rf 0.30 on TLC analysis. This fraction was purified by silica gel column and ODS- and NH_2-HPLCs giving three new compounds. Their structures were determined as de-N-methylpamamycins by MS spectrometry with the aid of labeled compounds prepared in a methionine-methyl-d_3 feeding culture. De-N-methylpamamycins had stronger aerial mycelium-inducing activity and weaker growth-inhibition activity than the corresponding pamamycin with the same alkyl group arrangement.2.Search for N,N-didemethylpamamycins To search the presumed biosynthetic precursor, N,N-didemethyl- pamamycin, we cultured Streptomyces alboniger in the presence of methylation inhibitors. As a result, it was found in the extract of DL-ethionine feeding culture. Further investigation on the time of application and dose of ethionine will improve the yield.3.Isolation of pamamycin homologues with long alkyl side chain Streptomyces sp. HKI-0118 is reported to produce new pamamycin homologues with long alkyl side chain, but their isolation is not achieved. We succeeded in the isolation of these homologues by two NH_2-HPLC columns connected in series.