Cyclodextrins enhance the antioxidant activity of essential oils from three Lamiaceae species

In the present study, the effect of S-cyclodextrin (beta-CD) and 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD) on the antioxidant activity and storage stability of the essential oils (EOs) from Lavandula viridis, Lavandula pedunculata subsp. Iusitanica and Thymus lotocephalus (Lamiaceae) was investigated. The presence of both cyclodextrins (CDs) was found to produce a remarkable enhancement on the antioxidant activity as assessed by the oxygen radical absorbance capacity (ORAC) assay. The highest free radical-scavenging effect was observed in the EO from T. lotocephalus, particularly at the highest concentration of HP-beta-CD (i.e., 1900 mu moI(TE)/g(EO)). Moreover, the antioxidant activity of the EO/HP-beta-CD complexes was found to be considerably stable over 30 days, at 4 degrees C, possibly due to the higher solubility of the modified beta-CD. The results obtained suggest that these systems can be a very interesting alternative as a natural source of antioxidants for different applications such as in the food preservation field. (C) 2015 Elsevier B.V. All rights reserved.