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Title: Controlled release of B-carotene in B-lactoglobulin-dextran conjugates nanoparticles in vitro digestion and the transport with Caco-2 monolayers

item YI, JIANG - Jiangnan University
item Lam, Tina
item Yokoyama, Wallace - Wally
item Cheng, Luisa
item ZHONG, FANG - Jiangnan University

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2014
Publication Date: 9/3/2014
Citation: Yi, J., Lam, T.I., Yokoyama, W.H., Cheng, L.W., Zhong, F. 2014. Controlled release of B-carotene in B-lactoglobulin-dextran conjugates nanoparticles in vitro digestion and the transport with Caco-2 monolayers. Journal of Agricultural and Food Chemistry. 62(35):8900-8907.

Interpretive Summary: Emulsions of beta-carotene encapsulated by beta-lactoglobulin (BLG) and beta-lactoglobulin proteins with a large carbohydrate molecule (dextran) attached (BLG-dextran). We found that under slightly acidic conditions the BLG emulsions aggregated whereas the BLG-dextran emulsions did not due to steric hindrance. Both emulsions were taken up by cells.

Technical Abstract: Undesirable aggregation of nanoparticles stabilized by proteins may may occur at the protein’s isoelectric point when the particle has zero net charge. Aggregation may be reduced bychanging the isoelectric point by conjugation of free amino groups with reducing sugars (Maillard reaction). Alternatively, addition of bulky groups may also reduce aggregation by steric hindrance. Dextran molecules about three times larger than beta-lactoglobulin (BLG) were conjugated to BLG. The BLG-dextran conjugates were characterized by SDS-PAGE and CD. Nanoparticles (60-70 nm diameter) of beta-carotene (BC) encapsulated by BLG or BLG-dextran were prepared by the homogenization-evaporation method. Dextran conjugation prevented the flocculation or aggregation BLG-dextran particles at pH ~4-5 compared to very large sized aggregates of BLG nanoparticles. The release of BC from BLG and BLG-dextran nanoparticles under acidic gastric conditions was 6.2 ± 0.9% and 5.4 ± 0.3%, respectively. The release of BC from BLG-dextran nanoparticles by trypsin digestion was 51.8 ± 4.3% of total encapsulated BC and BLG nanoparticles was 60.9 ± 2.9%. Neither BLG-BC nanoparticles or the Maillard reacted BLG-dextran conjugates were cytotoxic to Caco-2 cells, even at 10 mg/mL. The apparent permeability coefficient (Papp) of Caco-2 cells to BC was improved by nanoencapsulation, compared to free BC suspension. The results indicate that nanoparticles of BC encapsulated by ß-lactoglobulin conjugated with bulky dextrin groups are more stable to aggregation under gastric pH conditions but have good release and permeability properties under simulated intestinal conditions.