Talaromynoids A–E: Five New Fusicoccane Diterpenoids from the Endophytic Fungus <i>Talaromyces</i> sp. DC-26
Peng Zhou, Xiaotian Zhang, Chong Dai, Shan Yan, Mengsha Wei, Wenya Feng, Qin Li, Junjun Liu, Hucheng Zhu, Zhengxi Hu, Chunmei Chen, Yonghui Zhang
Abstract
Talaromynoids A–E (1–5), five new fusicoccane diterpenoids, were obtained from the endophytic fungus Talaromyces sp. DC-26, which was isolated from a wild leech. Talaromynoid A (1) represents the first fusicoccane diterpenoid bearing an unexpected 5–7–5 tricyclic ring system, which is possibly derived from normal 5–8–5 ones by ring contraction. Talaromynoid E (5) is characterized by an unusual oxygen bridge between C-1 and C-8 that establishes the eight-membered ring B to be a 9-oxo-bicyclo[3.3.1]nonane. Structures of 1–5 with absolute configurations were determined by extensive NMR spectral analyses, electronic circular dichroism (ECD) calculations, X-ray diffraction analyses, and acid hydrolysis.