Seasonal variations of rosmarinic and carnosic acids in rosemary extracts. Analysis of their in vitro antiradical activity

1 University of Reading. School of Plant Sciences. Plant Sciences Labortory. Whiteknights. P.O. Box 221. Reading RG6 6AS. UK. Present address: Facultad de Farmacia.Universidad de La Laguna. Avda. Astrofísico Francisco Sánchez, s/n. 38071 La Laguna (Tenerife). Spain
2 Mediterranean Agronomic Institute at Chania. Department of Natural Products. Makedonias Str. P.O. Box 85. GR-73 100 Chania (Crete). Greece

Abstract

Rosemary plants were analysed using HPLC and eight different compounds (vanillic acid, caffeic acid, rosmarinic acid, naringin, hispidulin, cirsimaritin, carnosol and carnosic acid) were identified and quantified. The analysis of the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity revealed that rosmarinic and carnosic acids were the best rosemary scavengers with IC50 values of 27 and 32 µM, respectively. Environmental influences on rosmarinic and carnosic acids content in rosemary plants were studied over a period of one year under southern UK conditions. Carnosic acid reached the maximum concentrations in December, decreasing by 50% during the summer months, while rosmarinic acid showed a constant concentration during the year. The significance of these results has been discussed later in this paper.

Additional key words: antioxidant, diterpene, DPPH, phenolic acids, rosemary.