Preparation, characterization, and molecular modeling of sesamol/β-cyclodextrin derivatives inclusion complexes

Sesamol is a natural organic phenolic compound with great application potential in the food and chemical industries. However, its instability and poor aqueous solubility have hindered its usage. In our work, three inclusion complexes (ICs) with cyclodextrins (2-hydroxylpropyl-β-cyclodextrin [HP-β-CD], methyl-β-cyclodextrin [M-β-CD], sulfobutylether-β-cyclodextrin [SBE-β-CD]) as host molecules and sesamol as a guest molecule (molar ratio 1:1) were prepared by co-precipitation. Three β-CDs were considered as effective embedding materials to improve the water-solubility of sesamol. The characterization results and molecular model of the ICs revealed that sesamol could be inserted into the hydrophobic cavity of β-CDs with the lowest binding affinity (sesamol/HP-β-CD IC with −4.4 kcal/mol, sesamol/M-β-CD IC with −4.3 kcal/mol, sesamol/SBE-β-CD IC with −4.2 kcal/mol). Furthermore, the results of noncovalent interactions analysis based on reduced density gradients showed that the hydrogen-bonds and van der Waals interactions were the key driving forces in sesamol/HP-β-CD and sesamol/M-β-CD IC, while weak van der Waals forces were the key driving forces in sesamol/SBE-β-CD IC. In addition, the radical scavenging capacity of sesamol/ HP-β-CD IC was significantly higher than free sesamol and other two ICs. Thus, HP-β-CD was the optimal host molecule for the preparation of sesamol inclusion complex.