β-Cyclodextrin Supramolecular Microcapsules and Antioxidant Activity of Laurus nobilis Essential Oil

Laurus nobilis essential oil (LEO) was isolated by microwave-assisted hydro-distillation in a yield of 2.7 %. The obtained oil from China was analyzed by GC and GC/MS. The main components from the oil were terpinyl acetate (23.14 %), followed by terpineol (5.83 %), caryophyllene (5.27 %), eucalyptol (5.25 %), and methyl eugenol (5.25 %). Supramolecular micro-capsules of beta-cyclodextrin (beta-CD), heptakis (2,6-di-methyl) beta-CD (DM-beta-CD), mono[2-O-(2-hydroxyethyl)]-beta-CD (HE-beta-CD), and mono[2-O-(2-hydroxy-propyl)]-beta-CD (HP-beta-CD) with LEO were prepared and various affecting factors were examined in detail. Furthermore, the formation constants (K-a) and the thermodynamic parameters (Delta G, Delta H and Delta S) were determined in the ranges of 20-50oC. The results indicated that the stoichiometry of the LEO-beta-CD supramolecular microcapsules was 1: 1 (molar ratio), the K-a decreased with the increase of temperature, and the inclusion abilities were according to following order: beta-CD> HE-beta-CD> DM-beta-CD> HP-beta-CD. The antioxidant and DPPH free radical scavenging activity of LEO was higher than those of BHT and PG. But superoxide anion inhibitory activity was weaker than that of PG.