Annia Galano and Jorge Rafael León-Carmona, Universidad Autnoma Metropolitana-Iztapalapa, Mexico, describe evidence suggesting that coffee is one of the richest sources of healthful antioxidants and seems to protect against conditions such as Alzheimer’s disease and heart disease on the most fundamental levels. As little is known about exactly how caffeine (CAF) works in scavenging free radicals, the researchers performed detailed theoretical calculations using density functional theory on caffeine’s interactions with different reactive oxygen species (ROS).

It was found that caffeine is inefficient for directly scavenging O₂^•− and ^•OOCH₃ radicals and most likely other alkyl peroxyl radicals. The overall reactivity of CAF toward ^•OH was found to be diffusion-controlled, regardless of the polarity of the environment, supporting the excellent ^•OH scavenging activity of CAF. CAF is predicted to be a modest scavenger of ^•OCH₃, and probably of other alkoxyl radicals, and a poor scavenger of HOO^•. Radical adduct formation has been identified as the main mechanism involved in the direct ROS scavenging activity of CAF.

The excellent consistency with the results that other scientists have reported from animal and other experiments supports the reliability of the calculations.

• Is Caffeine a Good Scavenger of Oxygenated Free Radicals?,
  Jorge Rafael Len-Carmona and Annia Galano,
  J. Phys. Chem. B 2011, 115 (15), 4538–4546.
  DOI: 10.1021/jp201383y