The Geographical Variation and Antimicrobial Activity of African Wormwood (Artemisia afra Jacq.) Essential Oil

The aerial parts of 16 individual Artemisia afra plants from four natural populations were hydrodistilled and the essential oil analyzed by GC/MS. The oil composition varied quantitatively and qualitatively within and between natural populations and showed no correlation to the geographical distribution. The antimicrobial activity was demonstrated by means of time-kill methodology using the respiratory pathogens C. neoformans and K. pneumoniae. Antimicrobial activity was most prominent within 10 min at concentration 0.75% for K. pneumoniae and within 60 min at concentration 1% for C. neoformans. Investigation of the four major compounds most abundant in the A. afra oil (artemisia ketone, 1,8-cineole, α-and β-thujone) indicated minimal antimicrobial activity when investigated independently and in various combinations against K. pneumoniae.