Diaporaustalides A–L, Austalide Meroterpenoids from a Plant Endophytic Diaporthe sp.

Twelve new austalide meroterpenoids (1–12) were isolated from the endophytic fungus Diaporthe sp. XC1211. Their structures were elucidated by extensive spectroscopic analysis. The absolute configurations of compounds 1, 3, 4, and 6 were established by single-crystal X-ray diffraction, whereas those for the others were established by experimental electronic circular dichroism (ECD) data analysis. Compounds 1–12 represent a rare class of austalides with a 24α-CH3. Compounds 2 and 5 demonstrated potent proliferation inhibitory effects against LPS-induced B cells with IC50 values of 6.7 (SI = 3.6) and 3.8 (SI > 13) μM, respectively. Compounds 2 and 5 decreased the secretion of IL-6 in LPS-induced B cells in a dose-dependent manner.本研究从内生真菌拟茎点霉属（Diaporthe）菌株XC1211中分离得到12个全新的澳斯特利型杂萜类化合物（1–12）。通过全面的波谱学分析阐明了所有化合物的化学结构。其中，化合物1、3、4和6的绝对构型通过单晶X射线衍射法确定，其余化合物的绝对构型则通过实验电子圆二色谱（ECD）数据分析予以确证。化合物1–12均属于一类罕见的带有24α-甲基取代的澳斯特利型杂萜。化合物2和5对脂多糖（LPS）诱导的B细胞展现出强效的增殖抑制活性，其半最大抑制浓度（IC₅₀）分别为6.7（选择指数SI=3.6）和3.8（选择指数SI>13）μM。化合物2和5可呈剂量依赖性地降低脂多糖诱导的B细胞中白细胞介素6（IL-6）的分泌水平。