Phosteoid A (1), a highly oxygenated norsteroid featuring an unusual 6/5-5 tricyclic ring skeleton, along with two known steroids 5a,8a-epidioxyergosta-6,22-dien-3b-ol (2) and ergosterol (3), were isolated from the deep-sea-derived fungus Phomopsis tersa FS441. The structure of 1 was fully elucidated on the basis of extensive spectroscopic analysis and electronic circular dichroism (ECD) calculation. Its plausible biosynthetic pathway was also proposed. Additionally, compound 1 was evaluated for in vitro cytotoxicity and anti-inflammatory activity.

中文翻译：

---

Phosteoid A，一种来自深海真菌Phomopsis tersa FS441的高度氧化的类固醇

Phosteoid A（1），一种高度氧化的类固醇，具有不寻常的6 / 5-5三环骨架，以及两种已知的类固醇5a，8a-epidioxyergosta-6,22-dien-3b-ol（2）和麦角甾醇（3）分离自深海真菌Phomopsis tersa FS441。1的结构在广泛的光谱分析和电子圆二色性（ECD）计算的基础上得到了充分阐明。还提出了其合理的生物合成途径。另外，评价化合物1的体外细胞毒性和抗炎活性。