*2.2. ORAC Assay*

The oxygen radical absorbance capacity (ORAC) assay was carried out according to Ou B. et al. and Dávalos A. et al. [26,27], with minor modifications. Briefly, 20 μL of stock solution of each extract (1 μg/mL) was distributed into a black 96-well plate. Then, 120 μL of fluorescein solution (70 nM final concentration), previously prepared with a phosphate bu ffer (pH 7.4, 75 mM), was added to each well. Peroxyl radicals were generated by adding 60 μL of AAPH 40 mM (Sigma-Aldrich, St. Louis, MO, USA). The final concentration of each extract in the assay well was 0.1 μg/mL. The plate was put in a spectrophotometer (Victor X3, PerkinElmer, USA) and the fluorescence detector was set at excitation and emission wavelengths of 484 and 528 nm, respectively. The fluorescence was read, after shaking, every 2 min for 60 min at 37 ◦C. Trolox (0–50 μM) was used as reference inhibitor. The area under the curve (AUC), of each extract, was calculated and the results were expressed as μM Trolox equivalent.

## *2.3. Cell Culture*

Human adenocarcinoma gastric epithelial cells (AGS, CRL-1739, LGC Standard S.r.l., Milano, Italy) were grown in DMEM/F12 medium (Gibco, Thermo Fisher Scientific, Waltham, MA, USA) supplemented with penicillin 100 units/mL (Gibco, Thermo Fisher Scientific, Waltham, MA, USA), streptomycin 100 mg/mL (Gibco, Thermo Fisher Scientific, Waltham, MA, USA), L-glutamine 2 mM (Gibco, Thermo Fisher Scientific, Waltham, MA, USA) and 10% heat-inactivated fetal bovine serum (Euroclone S.p.A, Pero, Italy), at 37 ◦C in humidified atmosphere containing 5% CO2. Human normal gastric epithelial cells (GES-1, kindly provided by Dr. Dawit Kidane-Mulat (University of Texas, Austin) were grown in RPMI 1640 medium, supplemented as previously described, and in the same atmospheric conditions. When cells reached 80–90% of confluence, usually every 4 days, they were detached from the flask (Euroclone S.p.A., Milan, Italy) using trypsin-EDTA 0.25% (Gibco, Thermo Fisher Scientific, Waltham, MA, USA), counted, and replaced in a new flask (1 × 10<sup>6</sup> cell density per flask) to promote cell growth.
