Cytoprotective and anti-inflammatory properties of the bioaccessible fractions of encapsulated, HPP-treated mango peel extracts

Introduction: Fruit by-products are a source of bioactive compounds (carotenoid and phenolic compounds) with antioxidant and anti-inflammatory properties, and ultrasound-assisted extraction, high-pressure processing, and encapsulation are sustainable technologies for their extraction and protection.

Methodology: Total carotenoid and phenolic compound (TCC and TPC)-mix extracts (EtOH/acetone, 54:36) of HPP-treated (200MPa/25ºC/5 min) Keitt mango peel obtained by UAE (A36 µm/10 min) were encapsulated with gum arabic by spray-drying at 150ºC (SF2) and by lyophilization (SF3). The two encapsulated extracts and the non-encapsulated extract (SF1) were submitted to in vitro gastrointestinal-digestion and TCC, TPC, and AA-FRAP were evaluated in bioaccessible fractions (BFs). Cytotoxicity in differentiated Caco-2 cells was checked with BFs at 24h. The cytoprotection viability, apoptosis, cell cycle and redox status (GSH), and anti-inflammatory activity (IL-6 and IL-8) of SFs pre-treated for 24h followed by 2h with 5 mM H₂O₂ to stimulate oxidative stress were obtained.

Results: The bioaccessible fractions of SF2 and SF3 presented higher TCC, TPC, and AA-FRAP than BF-SF1. The BFs recovered the viability levels of the control cells and increased cell viability versus digestion. The BFs increased viable cells and decreased early apoptosis. BF-SF2 and BF-SF3 showed greater cytoprotection by reducing late apoptosis. The BFs also decreased the sub-G1 cell cycle phase and allowed the recovery of disturbances in G0/G1 and G2/M evoked by H₂O₂. Oxidative stress decreased GSH, but it was recovered with BFs. The cytoprotective effect of BFs was confirmed, with it being statistically higher in BF-SF2 and BF-SF3 compared to BF-SF1. The BFs reduced the production of IL-8 and IL-6 versus H₂O₂, highlighting an anti-inflammatory effect of BF-SF2 and BF-SF3 compared to BF-SF1.

Conclusion. Greater TCC, TPC, AA, and cytoprotective and anti-inflammatory effects were observed in encapsulated (BF-SF2 and BF-SF3) compared to non-encapsulated (BF-SF1) extracts, although no differences were observed between spray-dryed BF-SF2 and lyophilized BF-SF3. Thus, both encapsulation techniques are effective to preserve the bioactivity of mango peel.