Structures and cellular activities of compounds isolated from Cymopolia barbata. (A) Structures of cymopol (1), 7-hydroxycymopol (2), cymobarbatol (3), cyclocymopol monomethyl ether (4). (B,C) Cymopols activated the ARE-luc reporter (24 h) in a dose-dependent manner in (B) LNCaP and (C) IMR-32 cells (n = 4). (D-F) Cells were treated with cymopols for 12 h and transcript levels were analyzed using qPCR analysis (n = 3). Cymopols were able to induce relative transcript levels of ARE-driven NQO1 in (D) IMR-32 and (E) LNCaP cells. (F) Cymopols and the NP extract increased transcript levels of various other ARE-regulated genes, without increasing levels of Nrf2. Symbol (✝) indicates cytotoxicity. (G) This induction of ARE-driven genes correlates with an induction of NQO1 protein levels after 24 h treatment in IMR-32 cells. (H) The induction of NQO1 by cymopol was not inhibited by pre-treatment with NAC. (I) Cymopol (1) and the NP extract were able to increase cellular GSH levels (n = 4, p < 0.05, t-test). tBHQ and sulforaphane (SF) served as positive controls.