Involvement of intracellular glutathione in regulating isoline-induced cytotoxicity in human normal liver L-02 cells.

Pyrrolizidine alkaloid isoline is isolated from the traditional Chinese medicine Ligularia duciformis. Our previous reports have already demonstrated isoline-induced liver injury in mice. The present study is designed to observe the involvement of intracellular reduced glutathione (GSH) in isoline-induced cytotoxicity in human normal liver L-02 cells. The results showed that isoline decreased the cellular GSH and the ratio of GSH and oxidized glutathione in a time- and concentration-dependent manner in L-02 cells. l-Buthionine-S-R-sulfoximine (BSO) is reported to inhibit cellular GSH biosynthesis, and further results showed that isoline decreased the cell viability in L-02 cells after pretreated with 25 μM BSO for 24 h. Furthermore, adducts of isoline and GSH were identified in L-02 cells using liquid chromatography/electrospray ionization tandem mass spectrometry (ion trap) for the first time. In conclusion, our study provides the strongest evidence to support the important roles of GSH in regulating isoline-induced cytotoxicity in human normal liver L-02 cells.