Enzymatic synthesis of phytosteryl lipoate and its antioxidant properties

In this work, an enzymatic route for synthesizing phytosteryl lipoate was successfully set up for the first time. The structure of final product phytosteryl lipoate was determined by Fourier Transform Infrared (FTIR), Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR). The maximum conversion of 71.2% was achieved when the following conditions were employed: 150mmol/L phytosterol, 1: 2.5M ratio of phytosterol to lipoic acid, 10g/L of 4Å molecular sieves and 60g/L Candida rugosa in 2-methyl-2-butanol/n-hexane (1:1, v/v) at 55°C for 96h. The physicochemical properties including solubility and antioxidant ability of phytosteryl lipoate in oil were assessed. The results revealed that phytosteryl lipoate possessed over twice as much oil solubility as free phytosterol and also showed better antioxidant ability. Investigation on its biological functions will be the main object in the future work.