Labdane diterpenes from Otostegia fruticosa

The new labdane diterpenes otostegin A (2), otostegin B (6) and 15-egi-otos tegin B (7) were isolated from the aerial parts of Otostegin fruticosa, bes ides the previously known labdanes preleoheterin (1), leoheterin (3), leope rsin C and 15-epi-leopersin C (4, 5). ballonigrin (9) and vulgarol (11), al ong with the iridoid glucoside 8-O-acetylharpagide (10). The structure eluc idation of all the isolated compounds was based on their spectral data and chemical derivatization. (C) 2000 Published by Elsevier Science Ltd.