Six previously undescribed piperidine alkaloids were isolated from the rhizomes of Alocasia macrorrhiza (L) Schott. Their structures were elucidated based on 1D and 2D NMR, IR, HR-ESI-MS spectroscopic analysis and the application of a modified Mosher method. All isolated alkaloids were evaluated for cytotoxicity against five human cancer cell lines (CNE-1, Detroit 562, Fadu, MGC-803, and MCF-7) using the KIT method. Only one compound exhibited cytotoxic effects against Detroit 562, Fadu, and MCF7 cell lines with IC50 values less than 10 mu M. (C) 2017 Elsevier Ltd. All rights reserved.