The interaction of allicin with bovine serum albumin and its influence on the structure of protein

The interaction of allicin with bovine serum albumin (BSA) and the effect of allicin binding on the structure of protein were investigated. The BSA fluorescence displayed decreased fluorescence strength after binding with allicin, which quenched BSA fluorescence in a concentration-dependent manner. The number of binding sites and binding constants were measured by fluorescent quenching method. The result of reverse phase HPLC showed that the peak of BSA shifted to higher retention time, which indicated that allicin had bound to BSA. 88.4 % of total free thiol groups of BSA have bound to allicin at the allicin/BSA molar ratio of 0.1. Allicin could destabilize the secondary and tertiary structure of BSA. At the allicin/BSA ratio of 0.1, the BSA's circular dichroism spectrum showed that allicin caused a decrease of alpha-helix content and a significant increase of the beta-sheet content (p < 0.05). Changes in surface hydrophobicity indicated that more hydrophobic groups were exposed due to the action of allicin. These results provide important insight into the study of prevailing role of protein in drug pharmacokinetics and pharmacodynamics.