Terpenes from the Fresh Stems of Commiphora gileadensis with Antimicrobial Activity

Phytochemical study directed by antimicrobial activity of the fresh Commiphora gileadensis stems CHCl₃ extract resulted in the isolation of compounds 1-9. The structures of the isolated compounds were elucidated utilizing various spectroscopic methods including 1D, 2D NMR and HRESIMS. Compounds 1, 3-5 were identified as the ent-verticillane-type diterpenes (1S,3E,7E,11R)-(+)-verticilla-3,7,12(18)-triene (1), (13S,14S)-Ent-13,14-epoxyverticillol (3), (9S,10S)-Ent-9,10-epoxyverticillol (4) and Ent-Verticillol (5) for the first time from Commiphora species. Compound 9 was identified as a diterpene with new skeleton and was given the name “gileadenol”. In addition, four know triterpenes were also identified as friedelin (2), oleanonic aldehyde (6), canyophyllal (7) and urs-12-en-3-one-28-al (8). The three tested ent-verticillane-type diterpenes expressed promising antimicrobial activity especially against K. pneumonia. The new diterpene as well as canyophyllal were less active.