Enhanced bioactivity of Citrus limon (Lemon Greek cultivar) extracts, essential oil and isolated compounds before and after encapsulation in liposomes

The antibacterial property of essential oils is the most widely studied area in human nutrition, food preservation and animal production [1,2]. The chemical composition of the essential oil from Citrus limon (Lemon Greek cultivar) was analysed by GC-MS. Limonene, β-pinene, γ-terpinene, neral and α-terpineol were identified as the main compounds. The antimicrobial properties of the essential oil was tested [using the diffusion technique of Bauer-Kirby (disc method) [3] against four Gram positive, four Gram negative bacteria, three human pathogenic fungi and the food-pathogen bacteria Listeria monocytogenes. In order to investigate any possible synergistic or antagonistic effect limonene, β-pinene, and γ-terpinene were isolated from the essential oil and their antimicrobial activity was determined before and after encapsulation in MLV liposomes (with ratios originally founded in the essential oil). The antioxidant activity was determined using two different methods (Rancimat and DSC) and compared with common commercial antioxidants BHT and α-tocopherol. Essential oil and its main compounds were encapsulated in liposomes and their antioxidant action was again estimated. Thermal-oxidative decomposition of the samples (liposomes pure and encapsulating extracts) was studied by DSC method. In all cases, the encapsulated material (essential oil or compound) proved to posses much stronger activity, than itself in pure form.

Acknowledgements: The study has been co-funded by 75% from E.E. and 25% from the Greek Government under the framework of the Education and Initial Vocational Training Program – Archimedes II.

References: [1] Keller, B.C. (2001) Trends Food Sci. Tech.: 12, 25. [2] Litwinienko, G. et al. (1999). Thermochim. Acta: 331, 79–86. [3] Bauer, A.W. et al. (1966) Am. J. Clin. Pathol.: 45, 493.