Complexation of rosemary-pepper essential oil (Lippia origanoides) with cyclodextrin and evaluation of the antimicrobial activity of the inclusion complexes

: Inclusion complexes are used to increase the solubility and stability of oils without altering their properties. Therefore, the present study proposes the preparation and physicochemical characterization of inclusion complexes of rosemary pepper essential oil ( Lippia origanoides ) using two different cyclodextrins, namely β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD), which were also analyzed for their antimicrobial, antifungal and antioxidant activities. The encapsulation results obtained by both kneading (K) and slurry (S) methods showed that complexes with HP-β-CD resulted in the lowest loss (< 3%) of essential oil during the process. The characterization of inclusion complexes by SEM, ED-XRF, XRD, NMR, TG, and DSC demonstrated that complexation using both cyclodextrins is an effective way to thermally stabilize the essential oil and would enable its incorporation into formulations without losing important properties. Indeed, the inclusion complexes successfully incorporated the characteristics of cyclodextrins and began to show mass loss and constituent degradation only at high temperatures. Hydroxyl and superoxide radical scavenging has been shown to be the primary mechanism responsible for antioxidant activity. Finally, the two most promising complexes, containing HP-β-CD and essential oil, did not show cytotoxicity.