Liposomes Encapsulating Artocarpus lakoocha Roxb. and Glycyrrhiza glabra L. Extracts: Characterization and Shelf Life of Freeze-Dried Vesicles

Liposome is the one way of encapsulation of extracts for reducing the extract degradation. This study was to prepare the liposome entrapped extracts of Artocarpus lakoocha Roxb. (L-Al), Glycyrrhiza glabra L. (L-Gg) alone and in combination of A. lakoocha and G. glabra extracts (L-AlGg). The liposomes were prepared by Mechanochemical method and freeze-drying. For stability of liposomes, storage at 4, 25 and 45°C for 8 weeks was performed. The trapping efficiency of liposomes and tyrosinase inhibitory activities of extracts entrapped in liposome were investigated. Results showed liposome morphology was the spherical vesicles evaluated by TEM. Before freeze-drying, liposomes had particle sizes of 156.966 ± 0.808, 140.8 ± 0.818 and 158.633 ± 4.193 nm for L-Al, L-Gg and L-AlGg, respectively. The entrapment efficiency of L-Al, L-Gg and L-AlGg was found to be 95.83 ± 13.48, 97.99 ± 5.23 and 93.90 ± 16.28 %, respectively. The tyrosinase inhibitory activities of released extracts from L-Al, L-Gg and L-AlGg were 81.57 ± 1.22, 68.92 ± 1.23 and 81.40 ± 0.64 %, respectively. After freeze-drying, the particle sizes of L-Al and L-AlGg were no significant changes, while L-Gg particle size was bigger (p < 0.01). The liposome entrapment and tyrosinase inhibitory activity of released extracts were not significantly changed after freeze-drying. This indicates good stability and no extract leakage of liposomes. In storage at 4°C for 8 weeks, the entrapment efficiency of L-Al, L-Gg, L-AlGg and tyrosinase inhibitory activity of released extracts were not significantly different, comparing with controls. When increasing temperature of storage effected on the significantly reduction of the entrapment of liposomes and the tyrosinase inhibitory activity of released extracts (p < 0.01). Therefore, the freeze-dried liposome and storage at low temperature is recommended for stabilizing liposome and extract quality.