Binding of Monoterpenes to Human Serum Albumin: Investigation of the Effect of Hydrophobicity and Structure

Monoterpenes of variable chemical structures and polarities were selected to be analyzed by RP-HPLC and to investigate their binding to human serum albumin. RP-HPLC analysis coupled with UV detector allowed to calculate the capacity factors and their logarithms (log k) for each monoterpene by isocratic method using 2 HPLC systems fitted to 2 columns of different lengths. Linear relationships of strong correlation factors were found between calculated log k and corresponding partition coefficient. Same monoterpenes were tested for binding to human serum albumin by fluorescence spectroscopy. Among the 17 monoterpenes studied only geraniol, pulegone and thymol of different monoterpenes subgroups proved binding to albumin. The hydrophobicity was not a criterion for the binding of a monoterpene to albumin at site I. These findings could be useful to explain the fast distribution of monoterpens and to understand the behavior of a monoterpene in media containing albumin such as encapsulation systems.