Catalposide protects Neuro 2A cells from hydrogen peroxide-induced cytotoxicity via the expression of heme oxygenase-1.

Catalposide, the major iridoid glycoside isolated from the stem bark of Catalpa ovata G. Don (Bignoniaceae) has been shown to possess anti-microbial, anti-tumoral, and anti-inflammatory properties. Heme oxygenase-1 (HO-1) is a stress response protein and is known to play a protective role against the oxidative injury. In this study, we examined whether catalposide could protect Neuro 2A cells, a kind of neuronal cell lines, from oxidative damage through the induction of HO-1 protein expression and HO activity. The treatment of the cells with catalposide resulted in dose- and time-dependent up-regulations of both HO-1 protein expression and HO activity. Catalposide protected the cells from hydrogen peroxide-induced cell death. The protective effect of catalposide on hydrogen peroxide-induced cell death was abrogated by zinc protoporphyrin IX (ZnPP IX), a HO inhibitor. Additional experiments revealed the involvement of CO in the cytoprotective effect of catalposide-induced HO-1. These results indicate that catalposide is a potent inducer of HO-1 and HO-1 induction is responsible for the catalposide-mediated cytoprotection against oxidative damage.