Terpenes from the Fresh Stems of Commiphora gileadensis with Antimicrobial Activity

Abstract

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.