Antioxidant activity of fresh and dry herbs of some Lamiaceae species

The herbs of lemon balm, oregano, and peppermint were analysed immediately after harvest and after drying to determine their antioxidant activity and content of total phenolics, l-ascorbic acid, and carotenoids. The strongest inhibition of linoleic acid (LA) peroxidation was found for fresh and dried oregano. For peppermint and lemon balm it was significantly lower and decreased after drying. The ability to scavenge the free radical DPPH (2,2-diphenyl-1-picrylhydrazyl) was very high in almost all tested samples, exceeding 90%. The three species tested had a very high content of total phenolics and drying of oregano and peppermint resulted in their considerable increase. The highest content of ascorbic acid was determined in fresh peppermint and lemon balm and carotenoid content was at a similar level in all the species tested. Drying caused great losses of these compounds.