COFFEE IS A SOURCE OF THE NITRATIVE FREE RADICALS: COMPARISON BETWEEN UNROASTED AND ROASTED COFFEE PREPARED AS AN AQUEOUS EXTRACTS AND BEVERAGE DRINKING SOLUTIONS

Background and Aim: Coffea arabica (Arabica) beans contained a plenty of polyphenols that act as antioxidants. The antioxidant activity of the green beans is progressively decreased with the extent of roasting and at the same time, simultaneous generation of heterogenous compounds that possessing antioxidant activity. The aim of this study is to demonstrate the generation of nitric oxide and peroxynitrite from green and roasted coffee and to show the effect of roasting on the levels of these nitrative radicles.

Materials and Methods: This in vitro study was conducted in the Department of Pharmacy, The College of Ausol Al-Deen University in Baghdad-Iraq during 2016. Different concentrations of green (unroasted) and brown (roasted) coffee beans were prepared as aqueous extract and as a drinking solution beverage. The levels of nitric oxide (NO-) and peroxynitrite (ONOO-) were measured in each coffee solution.

Results: The levels of NO- and ONOO- were significantly higher in the coffee drinking beverage that an aqueous extracted solution. These levels were significantly lower in the unroasted (green) coffee solution compared with the roasted (brown) coffee. The generated levels of nitrative free radicals were coffee bean concentration dependent. The estimated ratio of NO- to the ONOO- of the green coffee prepared by extraction or as a beverage was 0.19 and 0.14 compared with 0.12 and 0.29 of the brown coffee respectively.

Conclusion: Coffee beans prepared by different ways are the source of nitrative free radical generation which tended to be high levels when it is roasted and prepared as a drinking solution beverage. The dual effects of generating the nitric oxide and peroxynitrite explained the limited effects of coffee beverage on the health.