Diterpenoids from the aerial parts of Orthosiphon aristatus var. aristatus

- Nine new diterpenes were obtained from Orthosiphon aristatus var. aristatus.
- The structures were determined by extensive spectroscopic analysis.
- Compounds 13, 17, and 23 showed weak cytotoxicity against three cancer cell lines.

Seven new isopimarane diterpenoids, orthoarisins A−G (1-7), a new secoisopimarane diterpenoid, orthoarisin H (8), a new staminane diterpenoid, orthoarisin I (9), together with 15 previously reported diterpenoids were isolated from the aerial parts of Orthosiphon aristatus var. aristatus. Their structures were established on the basis of extensive spectroscopic analysis. Compounds 13, 17, and 23 showed weak inhibitory activity on the proliferation of the SKOV3, DU145, and PC-3 cell lines.