Effect of an acid treatment on the phytochemical and antioxidant characteristics of extracts from selected Lamiaceae species

Aqueous-methanol extracts were prepared from basil (Ocimum basilicum L.), bay (Laurus nobilis L.), oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.), sage (Salvia officinalis L.), savory (Satureja hortensis L.) and thyme (Thymus vulgaris L.) by maceration and their phytochemical and antioxidant characteristics were assessed. Each extract was submitted to an acid treatment (1.2 N HCl in 50% methanol) to determine whether such a process had an effect upon their chemistry and antioxidative efficacy. The treatment appeared to have improved the antioxidant potency of the extracts in general; however, there were some exceptions. The treatment did not increase the Fe(III) reductive activity of the extracts from basil or bay samples nor the ability of the oregano and sage extracts to scavenge 1,1-diphenyl-2-picrylhydrazyl radicals at pH 7.4. The Folin-Ciocalteu phenol content of the basil extract was not increased with acid treatment. © 2004 Elsevier Ltd. All rights reserved.