Interaction between cytotoxic effects of Xanthomicrol and Noscapine on PC12 cells

In this study, the cytotoxic effects of methanolic leaf extract of Dracocephalum kotschyii Boiss and methanolic seed extract of Peganum harmala Linn. Alone and in combination, was studied against PC12 and B65 cell lines using MTT assay. In addition, the cytotoxicity of harmine, major indol alkaloid in Peganum harmala was studied against these cells. Furthermore, the cytotoxicity of xanthomicrol, a flavone in methanolic leaf extract of Dracocephalum kotschyii and noscapine, and the interaction between them was also investigated against PC12 cell line. Dracocephalum kotschyii and Peganum harmala and their combination, Spinal-Z, showed cytotoxicity against cell lines tested in a concentration dependent manner. Cytotoxic effects of harmine and xanthomicrol could explain the cytotoxic effect of P. harmala and Dracocephalum kotschyii on these cells. Although, combination of these extracts showed cytotoxicity, but there was a decrease in comparison to each of the extracts alone. P. harmala seeds extract showed a greater preferential cytotoxic effect than D. kotschyii leaves extract on PC12 cells. Such a preferential cytotoxicity was also seen for harmine on the same cell line. Xanthomicrol and noscapine were able to inhibit proliferation of PC12 cells with IC50 of 24.5 µg/mL and 2.8 µg/mL respectively. The cytotoxic effects of xanthomicrrol increased in the presence of noscapine. Flow cytometry analysis showed that xanthomicrol induced apoptosis in HL60 cell lines.