Effects of sonication and ultrasound on properties and bioactivities of liposomes loaded with hydrolyzed collagen from defatted sea bass skin conjugated with epigallocatechin gallate.

Hydrolyzed collagen (HC) from defatted sea bass skin conjugated with 3% epigallocatechin gallate (EGCG) was prepared and the resulting HC-EGCG conjugate at various levels (0.25%-2%, w/v) was loaded into liposome. The obtained liposomes were subjected to sonication (S). Liposome loaded with 1% conjugate showed the highest encapsulation efficiency (EE) (p < .05). When the ultrasound-assisted process (UAP) at different amplitudes (20% and 40%) and times (2, 5, 10, and 15 min) were implemented, the highest EE of conjugate-loaded liposome was found at 20% amplitude for 2 min (p < .05). When S-liposome and UAP-liposome were lyophilized, decreasing EE of both samples was observed (p < .05). Lyophilized UAP-liposome had higher stability than lyophilized S-liposome during storage at 25℃ for 28 days. Additionally, antioxidant activity in the gastrointestinal track model system (GIMs) and digest obtained from GIMs were higher for UAP-liposome (p < .05). Therefore, liposome can be used for the delivery of conjugate. PRACTICAL APPLICATIONS: HC from defatted sea bass skin is considered to possess several bioactivities, especially skin nourishment and bone strengthening. Nevertheless, antioxidant activity, related to the treatment of several ailments, is still low for HC. Thus, grafting of HC with polyphenol such as EGCG via free radical method can be used for the enhancement of the antioxidant activity of HC. Although the resulting conjugate has augmented activity, it is unstable during storage and in the gastrointestinal digestion system. Liposome is a promising means to stabilize the conjugate under harsh condition, especially with the aid of the UAP. Thus, liposome loaded with conjugate having the reduced size has higher antioxidant activity with increased stability, which can have a wider range of applications.