E580 elexsys series

X-band (9GHz) EPR measurements were performed to determine the scavenger activity of the samples 1, 4–7 and 9, and capsaicin towards the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical. All solutions were prepared in acetonitrile with a final concentration of 0.1 mM of DPPH and 2.2 mM of the test compound. The spectra were recorded at room temperature using a Bruker E580 Elexsys Series and a Bruker cavity ER 4122 SHQE. The compounds, and capsaicin, were added to the radical solution and after an incubation time of 20 min the EPR spectrum was recorded. The signal of the DPPH before and after the addition of each compound was acquired and the relative area or double integral of the EPR spectra were calculated. The scavenger activity of the samples was calculated as follows: $$R=\frac{H_0-H_x}{H_0}\times 100$$
where H₀ and H_x are the double integral or area of the EPR signal in the absence or after the addition of the antioxidant compound, respectively, and the scavenger ratio (R) represents the percentage of scavenger activity of the samples. The reduction of the intensity of the signals is much more evident for those samples which have higher antioxidant activity.

The reaction solution was prepared adding 7b and 11h (40 mM), DMPO (60 mM), and laccase (0.12 mM) in 1,4-dioxane/sodium acetate buffer (9:1 ratio). To perform the EPR experiments, capillaries of 1.2 mm diameter were filled in and inserted in a quartz tube of 3 × 3.5 I.D. × O.D. CW (continuous wave) X-band (9 GHz). Experimental condition: 9.86 GHz 123 microwave frequency, 0.1 mT modulation amplitude, and 0.2 mW microwave power. EPR spectra were recorded at room temperature with a Bruker E580 Elexsys Series, using the Bruker ER4122 SHQE cavity. A simulation was carried out with the Easyspin simulation program 5.2.28 version, using the “garlic function”.