Relevance of Carnosic Acid Concentrations to the Selection of Rosemary, Rosmarinus officinalis (L.), Accessions for Optimization of Antioxidant Yield

Methods were developed to identify and select accessions of rosemary, Rosmarinus officinalis (L.), producing optimum antioxidant activity. Extracts from 12 different rosemary accessions, using three solvents of varying polarity, were assayed for their antioxidant activity, and their major antioxidant compounds were identified and quantified by high-performance liquid chromatography (HPLC). Carnosic acid concentrations were correlated with (i) the free radical scavenging activity of these extracts, as measured by the 2,2-diphenyl-1-picrylhydrazyl assay (adjusted R 2 = 77.3%) and (ii) their inhibition of linoleic acid oxidation, as measured by the β-carotene assay (adjusted R 2 = 44.1%). The correlation was broadly confirmed by the production of volatile aldehydes as measured by the hexanal assay. The variation of carnosic acid concentrations in extracts of 29 accessions, grown in field trials at three sites in England, was determined. Keywords: Antioxidants; β-carotene; carnosic acid; DPPH•; rosemary; rosmarinic acid