Four undescribed pyrone derivatives, pestalopyrones A-D, containing unusual tricyclic 5/6/6 polycyclic skeletons, were isolated from the ethyl acetate extract of the endophytic fungus Pestalotiopsis neglecta S3 derived from the fresh stems of Rubia podantha Diels (Rubiaceae). Their planar structures were elucidated mainly by NMR and HRESIMS. Pestalopyrones A-D contained six contiguous chiral carbons, and the relative configurations of C-4, C-5, and C-8 in tricyclic 5/6/6 polycyclic skeletons were determined by ROESY spectra. For pestalopyrone B, the absolute configuration of C-16 was determined by the Mosher's method. All isolated compounds were tested for their cytotoxicity against cancer cell lines, antibacterial activity, and inhibitory effect on the lipopolysaccharide (LPS)-induced nitric oxide (NO) production, and the results showed that pestalopyrone A inhibited LPS-induced NO production with an IC50 value of 35.8 μM.

中文翻译：

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Pestalopyrones A–D，来自内生真菌 Pestalotiopsis lampa S3 的四种三环吡喃酮衍生物

四种未描述的吡喃酮衍生物，pestalopyrones AD，含有不寻常的三环 5/6/6 多环骨架，是从来自茜草科（茜草科）新鲜茎的内生真菌 Pestalotiopsis guessa S3 的乙酸乙酯提取物中分离出来的。它们的平面结构主要通过NMR和HRESIMS来阐明。Pestalopyrones AD 包含六个连续的手性碳，并且通过 ROESY 光谱确定了三环 5/6/6 多环骨架中 C-4、C-5 和 C-8 的相对构型。对于pestalopyrone B，C-16的绝对构型由Mosher方法确定。测试了所有分离的化合物对癌细胞系的细胞毒性、抗菌活性和对脂多糖 (LPS) 诱导的一氧化氮 (NO) 产生的抑制作用，