Self-assembled beta-lactoglobulin-conjugated linoleic acid complex for colon cancer-targeted substance

Beta-lactoglobulin (beta-LG) is a member of the lipocalin protein family and can bind a variety of hydrophobic molecules, such as fatty acids, in vitro. In this study, a potential colon-targeted antitumor drug was developed using bovine beta-LG as a carrier loaded with cis-9, trans-11 conjugated linoleic acid (CLA). The intrinsic tryptophan fluorescence intensity of beta-LG monitored by spectrofluorometer showed that 2.46 mol of CLA can be bound per mole of beta-LG. Dynamic light scattering showed the formation of a beta-LG-CLA self-assembled complex with particle size of 170+/-0.08 nm. After treatment with gastrointestinal pH and digestive enzymes, beta-LG-CLA complex showed very good stability in gastrointestinal conditions in vitro, measured by zeta potential analyzer and sodium dodecyl sulfate PAGE, respectively. In an intestinal model in vitro, the concentration of CLA in Caco-2 cells was detected by reverse-phase HPLC, and the level of CLA in cells after treatment with beta-LG-CLA complex was significantly greater than after treatment with CLA, which means beta-LG served as a capsular vehicle of CLA for intracellular transport. According to cell proliferation assay, beta-LG-CLA complex can inhibit the viability of Caco-2 cells, and the inhibition rate is significantly greater than with the same concentration of CLA (100 microM). The study revealed that bovine beta-LG as a carrier binding with CLA can potentially be used for colon cancer therapy.