Lipase-catalysed esters synthesis of cafestol and kahweol

Abstract

Cafestol and kahweol (C&K), two coffee diterpene alcohols with structural similarity which exhibit anticarcinogenic effects, were isolated from green coffee Arabica beans, followed by their lipase-catalysed esterification and purification by preparative high-performance liquid chromatography (HPLC). The isolation and enzymatic synthesis parameters of C&K esters were studied, with the latter optimised by a Central Composite Design; both procedures were monitored by gas chromatography. Scale up and improved isolation conditions resulted in 1.29 g of C&K, with 98% purity from 300 g of green Arabica beans. The highest C&K ester yields were observed using an alcohol:fatty acid molar ratio of 1:5, 73.3 mg mL−1 of CAL-B enzyme, 70 °C and 240 rpm for 3 days in toluene, leading to 85–88% conversion among a variety of tested C&K esters, including n-C14:0-C20:0, C18:1, C18:2 and C18:3.