Antiprotozoal Diterpenes from Perovskia abrotanoides.

As part of a screening for new antiparasitic natural products from Iranian plants, -hexane and ethyl acetate extracts from the aerial parts of were found to exhibit strong inhibitory activity against and . The activity was tracked by high-performance liquid chromatography (HPLC)-based activity profiling. Preparative isolation by a combination of silica gel column chromatography and HPLC afforded 17 diterpenoids (1: -17: ), including 14 abietane-, two icetexane-, and one isopimarane-type derivatives. Among these, (5,10)-11-hydroxy-12-methoxy-20-norabieta-8,11,13-triene (2: ), 12-hydroxy-norabieta-1(10),8,11,13-tetraene-1,11-furan (6: ), and 12-methoxybarbatusol (9: ) were new compounds, the structure of which was established by comprehensive spectroscopic data analysis (one- and two-dimensional nuclear magnetic resonance, high-resolution electrospray ionization mass spectrometry, electronic circular dichroism). The antiprotozoal activity of the isolated compounds was evaluated against , and . Selectivity indexes (SI) were calculated in comparison to cytotoxicity on rat myoblast (L6) cells. Particularly active were 7-ethoxyrosmanol (4: ) with an IC of 0.8 µM against (SI 14.9) and an IC of 1.8 µM (SI 6.9) against , ferruginol (8: ) with an IC of 2.9 µM (SI 19.2) against , and miltiodiol (10: ) with an IC of 0.5 µM (SI 10.5) against . None of the compounds exhibited selective toxicity against (SI ≤ 1.6).