*2.1. Chemicals*

Griess reagent, benzoic acid, hydroxybenzoic acid, caffeic acid, cinnamic acid, coumaric acid, ferulic acid, gallic acid, protocatechuic acid, sinapic acid, syringic acid, vanillic acid, quercetin, angiotensin-converting enzyme (ACE), captopril, hydrogen peroxide (H2O2), and diacetyldichlorofluorescein were purchased from Sigma-Aldrich (St. Louis, MO, USA). Antibodies against p-eNOS, eNOS, p-Akt, Akt, Nrf-2, NQO-1, PCNA, HO-1, GCLC, and β-actin were obtained from Cell Signaling Technology (Beverly, MA, USA). Dulbecco's modified Eagle's medium (DMEM), fetal bovine serum (FBS), and penicillinstreptomycin were purchased from Hyclone (General Electric Healthcare Life Sciences, Mississauga, Canada). The structure of phenolic acids is indicated in Table 1.

**Table 1.** The structure of phenolic acids.

