Complexation of chlorogenic acid enhances the antiproliferative effect of lactoferrin to colon cancer cells

Lactoferrin (LF) shows good anticancer biological activity. Lactoferrin can combine with chlorogenic acid (CGA) in dairy drinks like milk coffee and milk tea. However, the nature and functional changes of LF after binding of CGA are not clear. The stability and binding properties of CGA on LF and its antiproliferative effect on colorectal cancer SW480 cells were investigated by spectroscopic and cell experiments. The results showed that CGA could stabilize LF solution by reducing particle size (below 90 nm) and increasing zeta potential (over 14 in the absolute value). With addition of CGA, the UV absorption peak of LF solution changed (from 287 nm shifted to 290 nm) and fluorescence quenching occurred at the same time. By molecular dynamics calculation, the binding site number of CGA to LF was between 2 and 3 sites. Negative Gibbs free energy of (delta G =-25.75 & PLUSMN; 0.84) indicated that the interaction between LF and CGA can occur spontaneously and effectively. Cell viability and apoptosis test showed that CGA and LF inhibited the growth of colorectal cancer SW480 cells in a synergistic way. Most of cells were arrested at G(0)/G(1) phase by the CGA-LF complex. We conclude that CGA can bind to LF to form a relatively stable complex under natural conditions, which increases their antiproliferative function on colorectal cancer cells.