Wulfenioidins D–N, Structurally Diverse Diterpenoids with Anti-Zika Virus Activity Isolated from <i>Orthosiphon wulfenioides</i>

Eleven diterpenoids, wulfenioidins D–N (1–11), classified into five distinct carbon skeletons with one unreported framework, and four modified abietane diterpenoids were isolated from the whole plant of Orthosiphon wulfenioides. The structures and absolute configurations were characterized by spectroscopic methods, single-crystal X-ray diffraction, and electronic circular dichroism analyses. Compounds 3 and 5 exhibited activity against Zika virus (ZIKV) with EC50 values of 8.07 and 8.50 μM, respectively, and showed no significant cytotoxicity toward Vero cells at 100 μM. Western blot and immunofluorescence experiments showed that compounds 3 and 5 interfered with the replication of the ZIKV by inhibiting the expression of the ZIKV envelope (E) protein.