Identification and occurrence of the bioactive β-carbolines norharman and harman in coffee brews

Abstract

Norharman and harman, two heterocyclic β-carboline alkaloids with biological activity, were found in brewed coffee. Identification and analysis were carried out by HPLC-MS and RP-HPLC-fluorescence, respectively. All tested samples of brewed coffee including ground coffee, decaffeinated coffee, instant coffee and espresso contained both norharman and harman in variable amounts. Norharman was the major β-carboline alkaloid in brewed coffee at levels up to 9.34 μg g^-1 in instant ground coffee compared with harman, which had levels up to 1.67 μg g^-1. The two β-carbolines appeared to be formed during roasting of the coffee beans. It is concluded that drinking coffee is a major exogenous dietary source of these bioactive β -carboline alkaloids previously reported as mild psychoactive compounds in animal studies and in vitro co-mutagens. These results support our previous conclusion that foods containing β -carbolines are an important exogenous source of these alkaloids in humans.

Keywords:

• Beta-CARBOLINE
• Norharman
• Harman
• Alkaloids
• Tryptophan
• Heterocyclic Amines
• Coffee
• Brewed Coffee