Antiproliferative compounds having a structure represented by formula (II), where n, R1, R2, R3, R4, and R5are as defined herein, can be used to treat tumors, optionally when conjugated to a ligand such as an antibody:抗細胞增殖化合物,其具有以式(II)表示之結構,其中n,R1,R2,R3,R4及R5均如本文定義,當視情況共軛至配位體譬如抗體時,其可用以治療腫瘤:(無元件符號說明)