(2S)-5,6,7,3′,4′-pentamethoxyflavanone, a citrus polymethoxyflavone ameliorates arsenic- and cigarette smoke extract-induced cytotoxicity via activating Nrf2-mediated defense system

•PMF activates the Nrf2-mediated defensive system.•PI3K, p38 MAPK, PKC and PERK, are involved in the PMF-induced activation of Nrf2.•PMF inhibits As- and CSE-induced damage in an Nrf2-denpendent manner.•The bioactivities of citrus polymethoxyflavone might be related to Nrf2 activation.•Citrus polymethoxyflavone is potential agent against oxidative stress-induced diseases.