The antioxidant activity of the essential oils of Artemisia afra, Artemisia abyssinica and Juniperus procera

The essential oils of Artemisia afra Jacq., Artemisia abyssinica Schultz-Bi p, and Juniperus procera Hoechst ex Endl. were examined for their potential radical scavenging activities. First a rapid evaluation of anti-oxidants w as made using a TLC screening method. The abilities of the volatile oils to act as nonspecific donors for hydrogen atoms or electrons were checked in the diphenylpicrylhydrazyl assay. Oils from all three species showed positi ve results and were examined further. The oils of A. afra and J. procera we re also effective hydroxyl radical scavenging agents when assessed in the d eoxyribose degradation assay, whilst oils from A. abyssinica exhibited a pa radoxical effect, In the in vitro assay for non-enzymatic lipid peroxidatio n in liposomes, the oils of A. afra and J. procera also displayed antioxida nt potential. It was not possible to measure the effect of A. abyssinica oi l in this system because certain components, e.g, alk-2-enals, interfered w ith the assay. The compounds that contribute to the radical scavenging acti vities of A. afra and J. procera were identified and then assessed for thei r effects in the various test systems. Finally, the qualitative and quantit ative compositions of the essential oils were studied by CC-MS, Copyright ( C) 2001 John Wiley & Sons, Ltd.