Two New Isoquinoline Alkaloids from Scolopendra Subspinipes Mutilans Induce Cell Cycle Arrest and Apoptosis in Human Glioma Cancer U87 Cells

Two new isoquinoline alkaloids 1-2 and seven known compounds 3-9 were isolated from the ethanol extract of centipede Scolopendra subspinipes mutilans L. Koch. The structures were elucidated by a combination of spectroscopic analyses including 1D and 2D NMR, and HRESIMS. Compounds 1-2 exhibited good cytotoxicity with IC50 values ranging from 1.19 to 31.28μM against six human cancer cell lines and low cytotoxicity against human normal liver L-02 cell lines, suggesting that compounds 1-2 had high specific cytotoxicity on human cancer cell lines. Further analyses showed that compounds 1-2 inhibited U87 cells proliferation by arresting cell cycle progress at G0/G1 phase and inducing apoptosis through loss of mitochondrial membrane potential (MMP), activation of caspase 9/3 and down-regulation of the Bcl-2/Bax protein ratio. The results suggest that compounds 1-2 induce apoptosis in U87 cells through the mitochondria apoptosis pathway, and they deserve further research as potential anti-glioma cancer agents.