Regioisomers Salviprolin A and B, Unprecedented Rosmarinic Acid Conjugated Dinorditerpenoids from Maxim.

Maxim is a perennial plant from the genus (family Lamiaceae). The roots of were long used as a traditional herb to treat blood circulation related illnesses in China. As part of our continuing interest in polycyclic natural products from medicinal plants, two unprecedented adducts comprised of a -diterpenoid and a 9'--rosmarinic acid derivative, linked by a 1,4-benzodioxane motif ( and ), were isolated from the roots of . Their structures were established by extensive spectroscopic approaches including 1D, 2D NMR, and HRFABMS. Their cytotoxic activities against five human tumor cell lines were evaluated.