Liposomes loaded with betel leaf (Piper betle L.) ethanolic extract prepared by thin film hydration and ethanol injection methods: Characteristics and antioxidant activities.

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Betel leaf ethanolic extract (BLEE), which was dechlorophyllized by sedimentation process was loaded in liposomes at 1 and 2% (w/v) concentrations using two different methods, namely thin film hydration (TF) and ethanol injection (EI) methods. Liposomes loaded with 1% BLEE and prepared by TF method (BLEE/L-T1) had the smallest particle size and paler color than BLEE/L-E1, BLEE/L-E2, and BLEE/L-T2 (p<.05). BLEE/L-T1 also showed strong stability as judged by its lowest zeta potential and polydispersity index. The highest encapsulation efficiency (EE) and lowest releasing efficiency (RE) were also found with BLEE/L-T1. No significant difference (p>.05) in the antioxidant activities was detected between the BLEE-loaded liposomes and BLEE solutions, indicating that encapsulation had no adverse effect on BLEE antioxidant potency. BLEE/L-T1 showed higher antioxidant stability than unencapsulated BLEE at the equivalent amount based on EE (BLEE/U-T1) during in vitro gastrointestinal tract digestion system. Therefore, BLEE/L-T1 could be an efficient delivery system for improving stability of antioxidant activities of BLEE. PRACTICAL APPLICATIONS: Despite the many benefits of betel leaf ethanolic extract, it still has some distinctive odor and slightly greenish color as well as instability induced by environment factors, which can limit applications in foods. Encapsulation of the betel extract in liposomes can be a good approach to mask its undesirable color and odor and to augment its antioxidant stability. Liposomal technology can be used to load betel leaf extract. However, different methods have been implemented to prepare liposomes that exhibit varying encapsulation efficacy as well as bioactivities. Thin film hydration method was shown to yield the liposome with better physical characteristics, higher encapsulation efficiency, slower release, and higher antioxidant stability than the ethanol injection method. Therefore, the thin film hydration method could be adopted to prepare stable liposomes loaded with betel leaf extract that possess antioxidant activity suitable for food applications.