A compound derived from the berries of the Bloodhorn tree has demonstrated activity against acute myeloid leukemia (AML), according to preclinical research published in Investigational New Drugs.
The compound, 7-formyl-10-methylisoellipticine, induced apoptosis in AML cells in a dose- and time-dependent manner.
It also significantly slowed tumor growth and reduced tumor mass in a mouse model of AML.
7-formyl-10-methylisoellipticine is derived from an ellipticine, which has been isolated from the berries of the Ochrosia Elliptica tree. The tree, also known as the Bloodhorn tree due to the shape and color of the berries, grows on the northeast coast of Australia and in the rainforests of Brazil.
“[We have] taken the natural product and restyled it with unique features to improve the potency and solubility,” explained Florence McCarthy, PhD, of University College Cork in Ireland.
“What is truly exceptional is that these features are not common in drugs, and so we aim to exploit this fully. There is also significant potential to apply this approach to other drugs in a similar fashion.”
For this study, Dr McCarthy and his colleagues first tested 7-formyl-10-methylisoellipticine in the AML cell line MV4-11. They tested a range of concentrations in an attempt to identify the minimum concentration that would cause significant cytotoxicity. It turned out to be 5 μM.
Over a period of 24 hours, 5 μM of 7-formyl-10-methylisoellipticine killed up to 40% of MV4-11 cells. And over 96 hours, 5 μM of 7-formyl-10-methylisoellipticine killed more than 90% of cells.
Further investigation revealed that 5 μM of 7-formyl-10-methylisoellipticine increases the sub-G1 phase of the MV4-11 cell cycle. And the compound functions, at least in part, by generating mitochondrial-derived reactive oxygen species.
The researchers then found that 7-formyl-10-methylisoellipticine is not toxic to BALB/c mice. The team injected the mice with 7-formyl-10-methylisoellipticine at a range of doses—5 mg/kg, 10 mg/kg, 25 mg/kg, and 50 mg/kg.
Regardless of the dose, the compound did not cause a change in body weight, significantly increase levels of alanine aminotransferase or aspartate aminotransferase relative to negative control, or significantly change cell morphology or tissue structure in specified major organs.
Finally, the researchers found that 7-formyl-10-methylisoellipticine has antitumor activity in an AML xenograft mouse model. Based on the toxicity experiments, the team used a dose of 25 mg/kg in these mice.
At this dose, 7-formyl-10-methylisoellipticine significantly slowed tumor growth and reduced tumor mass. Tumor growth was 4 times slower in mice treated with 7-formyl-10-methylisoellipticine than in control mice. And tumor mass was up to 7 times greater in controls than it was in treated mice.
Based on these results, the researchers said they plan to continue investigating the mechanism of action of ellipticines, which “have a clear potential clinical application.”
