Cytotoxic mannopyranosides of indole alkaloids from Zanthoxylum nitidum.

Three new mannopyranosides of indole alkaloids, methyl 7-(β-D-mannopyranosyloxy)-1H-indole-2-carboxylate (1), methyl 7-[(3-O-acetyl-β-D-mannopyranosyl)oxy]-1H-indole-2-carboxylate (2), and 2-methyl-1H-indol-7-yl β-D-mannopyranoside (3), were isolated from an EtOH extract of the roots of Zanthoxylum nitidum. Their structures were identified as new compounds on the basis of the spectroscopic analyses. Bioactivity evaluation revealed that these alkaloids possess significant cytotoxicities against all the tested tumor cell lines with IC50 values of less than 30 μM.