Phenolic esters are considered as promising functional food ingredients. However, their digestion, absorption and metabolism are still unclear. Tyrosol acyl esters (TYr-Es), hydroxytyrosol acyl esters (HTy-Es) and alkyl gallates (A-GAs) were hydrolyzed by carboxylesterase in plasma and exhibited slow release of polyphenols (phenolic acids). In vitro hydrolysis degrees initially increased and then decreased with the increasing carbon chain length (C2-C16). TYr-Es exhibited higher hydrolysis degrees compared to HTy-Es, and hydrolysis degrees of TYr-Es and HTy-Es were markedly higher than those of A-GAs. Due to the fast hydrolysis rates of TYr-Es and HTy-Es, they were undetectable in all rat plasma samples collected at several times within 24 h after administration. Whereas, A-GAs could be detected in rat plasmas and three absorption peaks were found in the pharmacokinetic profiles. Importantly, the T 1/2 , MRT, AUC 0-∞ , AUC 0-t in octyl gallate group were longer (or stronger) than those in propyl gallate and dodecyl gallate groups.
Guo-Bin Liang,Cheng Yang,Kang-Hong Wang,Shuangfei Li,Zhen Yang
As a new generation of water-immiscible solvents, hydrophobic deep eutectic solvents (HDESs) have shown great potential as green and sustainable reaction media for biocatalytic applications. Tyrosol is a major phenolic compound present in olive oil and wine with potential pharmacological benefits due to its strong antioxidant properties, and its application can be highly extended by increasing its lipophilicity through esterification. In this study, two lipases, one from Aspergillus oryzae (AOL) and another from Pseudomonas fluorescens (PFL), were immobilized on inorganic salt crystals (i.e. @Cu3(PO4)2) and on metal-organic frameworks (i.e. @HKUST-1). The structural features of these four new biocatalysts were characterized and their activity and stability assayed. They were successfully employed to catalyze the esterification of tyrosol to produce tyrosol esters in HDESs with excellent yields, which are comparable to, or even better than, the results obtained by using the most commonly used commercial lipase (i.e. Novozym 435 from Novozymes). The carboxylic acid-based HDESs provide not only a reaction medium but also an acylating agent for the enzymatic (trans)esterification reactions.
Kang-Hong Wang,Shuangfei Li,Ying-Fen Meng,Yong Zou,Guo-Bin Liang,Cheng Yang,Zhen Yang
Tyrosol is a principle phenolic compound present in olive oil and wine with great pharmacological potentials due to its strong antioxidant property. Its application can be highly extended by increasing its lipophilicity through esterification. In this study, tyrosol esters were synthesized by enzymatic transesterification of tyrosol with vinyl esters, with a commercial lipase from Novozymes (Novozym 435, Candida antarctica lipase B (CALB) immobilized on macroporous acrylic resin beads) as the catalyst, both in organic solvents and in ionic liquids. Methyl tert-butyl ether (MTBE) was the best solvent, offering complete conversions towards the synthesis of tyrosol esters with varying chain lengths (C2-C18) within 1 h. Taking the enzymatic transesterification between tyrosol and vinyl acetate as the model reaction, 18 organic solvents and 24 ionic liquids were screened, and their solvent properties (i.e. hydrophobicity, polarity, viscosity, water activity, and partition coefficients of substrate and product) were correlated to the enzyme activity. Upon enzyme screening, four new lipases were found to be highly efficient, relative to the best-performed Novozym 435 and Lipozyme TLIM (Thermomyces lanuginosus lipase (TLL) immobilized on silica gel), in tyrosol ester synthesis. This work provides enzymatic methods of esterifying tyrosol that are much more efficient than those reported in literature, and will shed light on re-consideration of the roles of solvents in nonaqueous enzymology.
危险品化学品经营许可证（带存储）