Controlled release characteristics of alkyl gallates and gallic acid from β-cyclodextrin inclusion complexes of alkyl gallates

The freeze-drying approach was used to create inclusion complexes utilizing alkyl gallates and β-cyclodextrin, namely dodecyl gallate, octyl gallate, butyl gallate, and ethyl gallate, which are exemplary examples of phenolic esters. The everted-rat-gut-sac model demonstrated that the inclusion complexes released alkyl gallates, which were subsequently hydrolyzed to generate free gallic acid, as evidenced by HPLC-UV analysis. Both gallic acid and short-chain alkyl gallates were capable of permeating the small intestinal membrane. The transport rate of gallic acid (or alkyl gallates) exhibited an initial rise followed by a drop when the carbon-chain lengths varied. The inclusion complex groups exhibited a superior sustained-release effect compared to the comparable alkyl gallates groups, thus possibly leading to higher bioavailability and stronger bioactivity. Moreover, altering the length of the carbon chain will allow for the effortless achievement of regulated release of phenolic compounds and short-chain phenolic esters from such β-cyclodextrin inclusion complexes.