Inhibition of reactive nitrogen species invitro and exvivo by thioredoxin h2 from sweet potato 'Tainong 57' storage roots

► TRX h2 inhibited on production of nitrite and superoxide radicals. ► TRX h2 caused a dose-dependent inhibition of the oxidation of DHR by peroxynitrite. ► TRX h2 suppressed the formation of ONOO−-mediated tyrosine nitration. ► TRX h2 showed a significant ability of inhibiting nitration of BSA. ► TRX h2 inhibited LPS-induced nitrite production in macrophage.