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

Abstract

The essential oils of Artemisia afra Jacq., Artemisia abyssinica Schultz-Bip. and Juniperus procera Hoechst ex Endl. were examined for their potential radical scavenging activities. First a rapid evaluation of antioxidants was 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 positive results and were examined further. The oils of A. afra and J. procera were also effective hydroxyl radical scavenging agents when assessed in the deoxyribose degradation assay, whilst oils from A. abyssinica exhibited a paradoxical effect. In the in vitro assay for non-enzymatic lipid peroxidation in liposomes, the oils of A. afra and J. procera also displayed antioxidant potential. It was not possible to measure the effect of A. abyssinica oil in this system because certain components, e.g. alk-2-enals, interfered with the assay. The compounds that contribute to the radical scavenging activities of A. afra and J. procera were identified and then assessed for their effects in the various test systems. Finally, the qualitative and quantitative compositions of the essential oils were studied by GC-MS.

Antidiabetic, antioxidant, and antilipid peroxidative activities ofDracocephalum polychaetumshoot extract in streptozotocin-induced diabetic rats:In vivoandin vitrostudies

“…The sample concentration (mg/mL) that required scavenging 50% of DPPH (IC 50 ) was calculated from the graph plotting inhibition percentage against the extract concentration (Burits et al, 2001).…”

Antioxidant Activity of the Essential Oils of Different Parts ofJuniperus communis. subsp.hemisphaerica. andJuniperus oblonga.

“…OH free radical scavenging activity of samples was measured with the procedure described by Burits et al (2001).…”

“…Finally, deoxyribose was omitted from the reaction mixture in order to see whether the compounds under examination themselves could form degradation products that react with TBA to make chromogen. By omission of deoxyribose from the reaction mixture, the tested oils were the only substrates to react with OH radicals and form TBA reactive species, TBARS (Burits et al, 2001). The volatile oil obtained from fruits and leaves of male and female J. oblonga, as well as standard compounds, limonene, a-pinene, and a-thujene, were the only substrates to react with OH radicals and to form TBARS.…”

The value of plant extracts with antioxidant activity in attenuating coccidiosis in broiler chickens

“…(Asteraceae) and Tulbaghia violacea Harv. (Liliaceae) were selected on the basis of previously reported antioxidant activity ([Allen et al, 1998], [Burits et al, 2001], [Kubec et al, 2002], [Zishiri, 2004], [Chikoto and Eloff, 2005], [Zheng and Wang, 2001] and [Velíšek et al, 2006]). According to Allen et al (1998) antioxidant compounds are known to reduce the severity of Eimeria tenella infections by ameliorating the degree of intestinal lipid peroxidation.…”