Design, Synthesis and Biochemical Evaluation of Novel Ethanoanthracenes and Related Compounds to Target Burkitt's Lymphoma

Lymphomas (cancers of the lymphatic system) account for 12% of malignant diseases worldwide. Burkitt’s lymphoma (BL) is a rare form of non-Hodgkin’s lymphoma in which the cancer starts in the immune B-cells. We report the synthesis and preliminary studies on the antiproliferative activity of a library of 9,10-dihydro-9,10-ethanoanthracene based compounds structurally related to the antidepressant drug maprotiline against BL cell lines MUTU-1 and DG-75. Structural modifications were achieved by Diels-Alder reaction of the core 9-(2-nitrovinyl)anthracene with number of dienophiles including maleic anhydride, maleimides, acrylonitrile and benzyne. The antiproliferative activity of these compounds was evaluated in BL cell lines EBV⁻ MUTU-1 and EBV⁺ DG-75 (chemoresistant). The most potent compounds 13j, 15, 16a, 16b, 16c, 16d and 19a displayed IC₅₀ values in the range 0.17–0.38 μM against the BL cell line EBV⁻ MUTU-1 and IC₅₀ values in the range 0.45–0.78 μM against the chemoresistant BL cell line EBV⁺ DG-75. Compounds 15, 16b and 16c demonstrated potent ROS dependent apoptotic effects on the BL cell lines which were superior to the control drug taxol and showed minimal cytotoxicity to peripheral blood mononuclear cells (PBMCs). The results suggest that this class of compounds merits further investigation as antiproliferative agents for BL.

Synthesis, Antiproliferative and Pro-Apoptotic Effects of Nitrostyrenes and Related Compounds in Burkitt's Lymphoma

BACKGROUND

Cancers of the lymphatic cells (lymphomas) account for approximately 12% of malignant diseases worldwide. The nitrostyrene scaffold is identified as a lead target structure for the development of particularly effective compounds targeting Burkitt's lymphoma (BL).

OBJECTIVES

The aims of the curent study were to synthesise a panel of nitrostyrene compounds and to evaluate their activity in Burkitt's lymphoma (BL).

METHODS

A panel of structurally varied compounds were designed and synthesised using Henry Knoevenagel condensation reactions. Single crystal X-Ray analysis confirmed the E configuration for six examples of these novel structures. A number of nitrostyrene-related compounds were also investigated including 1,3-bis(aryl)-2-nitropropenes together with heterocyclic scaffolds containing the nitrovinyl pharmacophore such as 3-nitro-2-phenyl-2H-chromenes. The antiproliferative activities of the compounds were evaluated using the BL cell lines EBV- MUTU-1 and EBV+ DG- 75 (chemoresistant) to establish preliminary structure-activity relationships.

RESULTS

Lead compounds with optimized nitrostyrene scaffolds and 3-nitro-2-phenyl-2Hchromene structures were successfully established with typical IC50 values of 0.45 µM and 0.47 µM in MUTU-1 cells and 1.41 µM and 1.92 µM, respectively, in DG-75 cells. The mechanism of cell death was identified as apoptotic and the lead compound was found to elicit comparable apoptotic effects to Taxol in Burkitt's lymphoma cell lines MUTU-1 and DG-75.

CONCLUSION

This class of pharmaceutically active compounds with potential for the treatment of Burkitt`s lymphoma suggest a potential role for nitrostyrene based agents in chemotherapy.