Photeroids A (1) and B (2), two structurally fascinating meroterpenoids, were isolated from the deep-sea-derived fungus Phomopsis tersa FS441. Their structures were sufficiently established by a comprehensive interpretation of the spectroscopic data, NMR spectra, and ECD calculation. Photeroids A and B represented the first phenolic sesquiterpene meroterpenoids featuring a highly fused 6/6/6/6 tetracyclic ring system derived through a rarely-occurring hetero-Diels-Alder reaction via an orthoquinone methide intermediate. Additionally, they were also evaluated for their cytotoxic activities against four human cancer cells, wherein compounds 1 and 2 exhibited moderate cytotoxic activities.

中文翻译：

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类胡萝卜素A和B，来自深海真菌Phomopsis tersa的独特酚-倍半萜烯类萜。

从深海来源的真菌Phomopsis tersa FS441分离出了类胡萝卜素A（1）和B（2），这两个结构令人着迷的类萜。通过对光谱数据，NMR光谱和ECD计算的全面解释，充分确定了它们的结构。类固醇A和B代表了第一个酚类倍半萜烯类萜金属，其特征是高度融合的6/6/6/6四环系统，是通过很少发生的异狄尔斯-阿尔德反应通过邻醌甲基化物中间体衍生而来的。另外，还评估了它们对四种人类癌细胞的细胞毒活性，其中化合物1和2表现出中等的细胞毒活性。