Immobilized lipase catalytic synthesis of phenolamides and their potential against α-glucosidase.

Although coumaroyltyramine (CT) derivatives are one kind of phenolamides with remarkable biological activities, the low content in plants would inhibit their potential use in food and pharmaceutical industries. Therefore, it is necessary to screen an efficient method to produce CT derivatives. A green and efficient method by using lipase as catalyst to synthesize a series of CT derivatives, was thus proposed. To obtain optimum reaction conditions, the effects of various parameters on conversion rate were firstly evaluated. An in vitro α-glucosidase inhibitory assay of synthesized compounds was then carried out, and the structure-activity relationship of these compounds was conducted. Under the optimum conditions (MTBE, Nu/S: 2/1, E/S: 20/1, 50 °C and 24 h), the conversion rates of synthesized compounds were above 65 %. The bioassay results indicated that N-trans-caffeoyltyramine and N-trans-feruloyltyramine had potent activities against α-glucosidase with IC50 of 30.08 μM and 31.94 μM, respectively. The structure-activity relationship results showed that the presence of -OH or -OCH3 group at C-3 position could boost the activities of CT derivatives. Meanwhile, the presence of -OH group at C-4 position and double bound on caffeoyl moiety as well as the presence of -OH group at C-4' position was essential for the activities of CT derivatives.