| Abstract
| - The specific antiradical activity against the hydroxyl radical of the water soluble components in greenand dark roasted Coffea arabica and Coffea robusta coffee samples, both in vitro by the chemicaldeoxiribose assay and ex vivo in a biological cellular system (IMR32 cells), were determined. All thetested coffee solutions showed remarkable antiradical activity. In the deoxiribose assay, all the testedsolutions showed similar inhibitory activity (IA%) against the sugar degradation (IA values rangedfrom 45.2 to 46.9%). In the cell cultures, the survival increase (SI%) ranged from 197.0 to 394.0%with C. robusta roasted coffee being significantly more active than the other samples. The coffeesolutions underwent dialysis (3500 Da cutoff membrane) to fraction their components. In both systems,the dialysates (MW < 3500 Da) either from green or roasted coffee, showed antiradical activity, whilethe only retentates (MW > 3500 Da) from the roasted coffee samples were active. The preparativegel-filtration chromatography of roasted coffee C. robusta dialysate gave three fractions active in thebiological system, all containing chlorogenic acid derivatives. The most active fraction was found tobe that containing the 5-O-caffeoilquinic acid, which shows a linear relation dose−response rangingfrom 0.02 to 0.10 mM. The results show that both green and roasted coffee possess antiradicalactivity, that their more active component is 5-O-caffeoyl-quinic acid, and moreover that roastingprocess induces high MW components (later Maillard reaction products, i.e., melanoidins), alsopossessing antiradical activity in coffee. These results could explain the neuroprotective effects foundfor coffee consumption in recent epidemiological studies. Keywords: Coffee; antiradical activity; neurodegenerative disorders; 5-O-caffeoyl-quinic acid
|
