Four new diterpenoids from Isodon eriocalyx var. laxiflora

Abstract

Four new diterpenoids, laxiflorins S-V (1–4), bearing four different types, and one known compound, laxiflorin O (5), were isolated from Isodon eriocalyx var. laxiflora. Compound 1 was the first example of ent-kauranoids bearing a unique C24 carbon framework and compound 4 was the first example of 3,4-seco-ent-abietane diterpenoids from the Isodon genus. Their structures were determined by spectroscopic methods (UV, IR, MS, NMR). [Figure not available: see fulltext.].