Isolation of coffee diterpenes by means of high-speed countercurrent chromatography

Many different physiological activities have been ascribed to coffee diterpenes, such as cholesterol increasing activity for the diterpenes kahweol and cafestol. Another member of this class, namely the diterpene 16-O-methylcafestol, is used as a marker substance for robusta coffee. Up to now, methodologies for the preparative isolation of these key coffee ingredients are still limited. In this study, high-speed countercurrent chromatography (HSCCC) was successfully employed for the isolation and purification of different diterpenes (i.e. kahweol, cafestol, 16-O-methylkahweol, 16-O-methylcafestol, dehydrokahweol, and dehydrocafestol) from Coffea arabica and Coffea canephora var. robusta. The solvent systems consisted of hexane–ethyl acetate–ethanol–water mixtures. Identity and purity of the isolated compounds were confirmed by high-performance liquid chromatography with photo diode array detection (HPLC-PDA) and HPLC–multiple mass spectrometry (HPLC–MSn) as well as NMR measurements.