Study of Antioxidant and Antimicrobial Activity of Chios Mastic Gum Fractions(Neutral, Acidic) Before and After Encapsulation in Liposomes

Abstract

Mastic is a well-known natural resin from the trunk and branches, of Pistacia lentiscus var. chia (Anacardiaceae), which is grown as endemic only in the Greek island of Chios. During this work, a total mastic gum extract was prepared after removal of the contained insoluble polymer in order to ameliorate solubility and enhance in vivo activity. To overcome the drawbacks (i.e solubility, bioavailability, etc.) of mastic gum extracts (acidic and neutral fraction), the selection of a suitable carrier is crucial. Three different methods of preparation, thin-film evaporation, freezing-thawing, and ethanol injection were used for the preparation of liposomes consisting of Phosphatidylcholine (PC) and Cholesterol (CH). The effect of PC: CH molar ratio on the percentage of mastic extract encapsulated was investigated. Mastic gum extracts components-liposomes interaction was studied using Fourier transform infrared (FT-IR) spectroscopy. The effects of different preparation methods on the physicochemical properties of colloidal systems were evaluated by means of surface morphology, field emission Scanning Electron Microscopy (SEM), and size distribution using a particle size analyzer. For the determination of the antioxidant activity two methods were used: I) The Rancimat method where the protection factor was determined for each sample and compared with known antioxidants. II) Differential Scanning Calorimetry (DSC) where the temperature of oxidation for each sample was determined. Moreover, the crude extract (EtOAc-MeOH) of mastic, as well as, its acidic and neutral fractions was assayed against a panel of 9 human and food pathogenic gram (±) bacteria and fungi.