Three oxygen-free radicals, superoxide anion (·O₂⁻), hydroxyl radical (·OH) and tert–butyl hydroperoxide radical (t–BuOO·) were trapped with 5,5–Dimethyl–1–pyrroline N–oxide (DMPO) by Electronic Paramagnetic Resonance, and three antioxidant compounds, ascorbic acid, chlorogenic acid and cysteine were tested as free radical scavengers, mixed with unusual antioxidants, such as glucose and citric acid. The EC₅₀ values revealed high reactivity of chlorogenic acid against ·O₂⁻ and t–BuOO·, while cysteine resulted the most active against ·OH. Cysteine against t–BuOO· had negative scavenging indexes, indicating pro-oxidant action. Glucose and citric acid resulted in negligible activities against ·O₂⁻ and t–BuOO· and active towards ·OH. Antioxidants were assayed after mixing, with addition of glucose and citric acid. As for ·O₂⁻ scavenging, a clear additive effect was found, while the ·OH scavenging of mixtures resulted in an antagonistic effect, with a prevalent scavenging action of glucose and citric acid. Interestingly, t–BuOO· scavenging showed a synergistic effect after the reciprocal mixing of the assayed antioxidants, 2.7-folds higher the percent scavenging with respect to sums of separate scavengers, with negligible effect observed by the addition of glucose and citric acid.