K. Vagionas, K. Graikou, I.B. Chinou*, D. Runyoro and O. Ngassapa

Abstract: Hydrodistilled volatile oils from the aerial parts of Artemisia afra and leaves of Leonotis ocymifolia var. raineriana were investigated, by a combination of GC and GC/MS. From A. afra 37 compounds were identified, representing 95.3% (area percent) of the total oil and from L. ocymifolia var. raineriana, 27 compounds were identified, representing 91.1% of the total oil. Among the identified components camphor (46.2%), a-thujone (15.2%), artemisia ketone (7.4%) and 1,8-cineole (4.2%) were found as the main components of A. afra oil and germacrene D (36.8%), (Z)- b-ocimene (7.9%), b-caryophyllene (7.0%) and (E)-b-ocimene (4.4%) were the major components of L. ocymifolia oil. Furthermore, the oils, as well as nine of their constituents, were evaluated for their antimicrobial activity, against six bacteria, two oral pathogens and three pathogenic fungi. The results showed that the oil of A. afra has a moderate antimicrobial activity, while the oil of L. ocymifolia exhibited a stronger one against Gram-negative bacteria and oral pathogens, and a weaker one against Gram-positive bacteria. This interesting profile can be attributed to the high content of the oil, of germacrene D which is known for its antimicrobial activity.

The genus <i>Artemisia</i> (Asteraceae) is spread worldwide comprising about 400 species of small herbs and shrubs and is divided into four subgenera <i>Artemisia, Seriphidium, Tridentatae</i> and <i>Dracunculus</i>. The genus has always been of great botanical, pharmaceutical and food industry interest (1,2). Although numerous data have already been published, there are still many problems in systematic interpretations because of the great infraspecific variation, structural complexity and the lack of data within several sections and subgenera (3). <i>Artemisia afra</i> Jacq. (Asteraceae), which is one of the oldest known medicinal plants in Southern Africa, is known as African wormwood, Wildeals, Lanyana and Menlonyana. It is a perennial bushy shrub, which grows up to 1.5 m high, with only a few leaves on the terminal ends of the branches and is indigenous to the mountain regions extending from East to North and South Africa. (4). <i>Artemisia afra</i> has widespread use in South African traditional medicine. Various preparations such as infusions, decoctions, molasses and alcohol extracts of the plant are used for the treatment of coughs, colds, chills, stomach ache, dry dyspepsia, as a purgative and for the cure of smallpox and malaria (4). The essential oil of <i>A. afra</i> has been reported to have several biological activities, mainly antimicrobial (5,6), antifungal (7) and antioxidative activity (5). Reports concerning the analysis of the oil of <i>A. afra</i> of different origins showed different qualitative and quantitative profiles (8–12).