A New Asymmetric ent-Kauranoid Dimer from Rabdosia rubescens

Objective To study the ent-kaurane diterpenoids from Rabdosia rubescens. Methods The compounds were isolated by chromatographies and their structures were identified by spectral analyses. Results Four compounds were isolated, they were bisrubescensin E (1), 2α,3α,24-trihydroxyurs-12-en-28-oic acid (2), 2α,3α,24- trihydroxyurs-12,20-(30)-dien-28-oic acid (3), and 6,7-dihydroxycoumarin (4). Conclusion Compound 1 is a new asymmetric ent-kauranoid dimer. Compound 2 is isolated from the plant for the first time. Compounds 3 and 4 are isolated from the plants of Rabdosia (Bl.) Hassk for the first time.