Staminolactones A and B and Norstaminol A:  Three Highly Oxygenated Staminane-Type Diterpenes from <i>Orthosiphon stamineus</i>

Abstract

[formula: see text] Staminolactones A (1) and B (2) and norstaminol A (3), three highly oxygenated staminane-type diterpenes having mild cytotoxic activities against highly liver-metastatic colon 26-L5 carcinoma cells, were isolated from the aerial part of the Vietnamese medicinal plant Orthosiphon stamineus (Lamiaceae). Their structures were elucidated on the basis of the extensive spectral analyses.