Antioxidant activities of rosemary (Rosmarinus Officinalis L.) extract, blackseed (Nigella sativa L.) essential oil, carnosic acid, rosmarinic acid and sesamol

Antioxidant activities of three pure compounds: carnosic acid, rosmarinic acid and sesamol, as well as two plant extracts: rosemary extract and blackseed essential oil, were examined by applying DPPH and ABTS(+) radical-scavenging assays and the ferric thiocyanate test. All three test methods proved that rosemary extract had a higher antioxidant activity than blackseed essential oil. The order of antioxidant activity of pure compounds showed variations in different tests. This was attributed to structural factors of individual compounds. Phenolic contents of blackseed essential oil and rosemary extract were also determined. Rosemary extract was found to have a higher phenolic content than blackseed essential oil. This fact was utilised in explaining the higher antioxidant activity of rosemary extract. (c) 2008 Elsevier Ltd. All rights reserved.