A new isoquinoline, 1,5-dihydroxy-4-methoxyisoquinoline (1), was obtained from Scolopendra subspinipes mutilans. Compound 1 showed moderate cytotoxicity on tumour cells with IC50 values ranging from 13 to 26 μm against five esophageal squamous cancer cells whereas low cytotoxicity against normal human esophageal epithelial cells. Isoquinoline ring oxidized at C(1), C(4), and C(5) can enhance its cytotoxicity. In addition, compound 1 showed potent inhibitory effect (inhibition rate > 50% at 13 μm) on cell migration in human umbilical vein endothelial cells. This article mainly studies the structure and activity of 1, and more modification of 1 as a potential anticancer agent. © 2017 Wiley-VHCA AG, Zurich, Switzerland