Volatile components of four Ethiopian Artemisia species extracts and their in vitro antitrypanosomal and cytotoxic activities

Artemisia species are one of the many traditional medicinal plants of Ethiopia used for the treatment of infectious and non-infectious health problems. In the present study, eight extracts prepared from leaves and aerial parts of four Artemisia species (Artemisia absinthium, A. abyssinica, A. afra, and A. annua) growing in Ethiopia were tested in vitro against bloodstream forms of Trypanosoma brucei brucei. The most active extract was the dichloromethane extract from aerial parts of A. abyssinica with an IC50 value of 19.13 μg/ml. A selectivity index (SI) of 8.24 was obtained with HL-60 cells treated with the same extract. Artemisinin, the best known antimalarial compound from A. annua showed antitrypanosomal activity with an IC50 value of 35.91 μg/ml and with a selectivity index of 2.44. The dichloromethane extracts of the four species were further investigated for their volatile components using GLC/MS. Camphor was detected in the four species and was found to be the principal compound (38.73%) of A. absinthium extract. Octa-3,5-diene-2,7-dione, 4,5-dihydroxy was detected in three species except in A. afra and was present as the main volatile component (54.95%) of A. abyssinica. Epoxylinalool was detected only in A. afra and was the principal component (29.10%) of dichloromethane extract of the plant. Deoxyqinghaosu was only present in A. annua and absent in the other three Artemisia species. Deoxyqinghaosu was the principal volatile component (20.44%) of the dichloromethane extract of A. annua. In conclusion, the dichloromethane extract from aerial part of A. abyssinica should be considered for further study for the treatment of trypanosomiasis.