Chitosan suspension enriched with phenolics extracted from pineapple by-products as bioactive coating for liposomes: Physicochemical properties and in vitro cytotoxicity

Abstract

The physicochemical stability of liposomes (L) loaded with bioactive compounds can be improved by coating them with chitosan, to give chitosomes (Ch). In addition, crosslinked chitosan can be obtained by using sodium tripolyphosphate (TPP). This study aimed to prepare L enriched with bioactive compounds extracted from pineapple by-products (PB) without coating or coated with chitosan or crosslinked chitosan-enriched with PB bioactive compounds, to obtain Ch and TPP-Ch, respectively. Then, we evaluated the encapsulation efficiency (EE) of total phenolic compounds (TPC), physicochemical properties, antioxidant and antimicrobial activities, and in vitro cytotoxicity. Ch and TPP-Ch had threefold larger content of TPC (331 μg of GAE/mL) and higher antioxidant activity than L (102 μg of GAE/mL) even though L had slightly higher EE than TPP-Ch (66 ± 10 % and 53 ± 9 %, respectively). Ch had the lowest EE (36 % ± 4), which highlights that Ch crosslinking is important for encapsulating bioactive compounds. Regarding in vitro cytotoxicity, avian fibroblast viability started to decrease 48 h after the cells were treated with 5 % L, Ch, or TPP-Ch suspension. Ch and TPP-Ch led to lower cell viability than L. Although Ch and TPP-Ch partially inhibited Staphylococcus aureus growth, only L showed antimicrobial activity against this microorganism, even 170 days after L was prepared. These results suggest that the novel methodology we used to prepare Ch and TPP-Ch can improve certain properties of chitosan-coated liposomes, which is significant for future advancements in food and pharmaceutical applications.