Synthesis and biological evaluation of tert-butyl ester and ethyl ester prodrugs of L-gamma-methyleneglutamic acid amides for cancer

Authors: KHAN, MD IMDADUL - University Of Mississippi; MAHDI, FAKHI - University Of Mississippi; PENFORMIS, PATRICE - University Of Mississippi; AKINS, NICK - University Of Mississippi; HOSSAIN, MD IMRAN - University Of Mississippi; Kim, Seong; SULOCHANA, SURESH - University Of Mississippi; ADAM, AMNA - University Of Mississippi; TRAN, TRISTAN - University Of Mississippi; TAN, CHALET - University Of Mississippi; CLAUDIO, PIER PAOLO - University Of Mississippi; PARIS, JASON - University Of Mississippi; HOANG, LE - University Of Mississippi

Submitted to: Bioorganic and Medicinal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2022
Publication Date: 12/21/2022
Citation: Khan, M.H., Mahdi, F., Penformis, P., Akins, N.S., Hossain, M., Kim, S., Sulochana, S.P., Adam, A.T., Tran, T.D., Tan, C., Claudio, P., Paris, J.J., Hoang, L.V. 2022. Synthesis and biological evaluation of tert-butyl ester and ethyl ester prodrugs of L-gamma-methyleneglutamic acid amides for cancer. Bioorganic and Medicinal Chemistry. https://doi.org/10.1016/j.bmc.2022.117137.
DOI: https://doi.org/10.1016/j.bmc.2022.117137

Interpretive Summary: According to the World Health Organization (WHO), breast cancer is the world’s most prevalent cancer. Cancer cells such as breast cancer are the primary biosynthetic precursors, fueling the TCA cycle with glutamine-derived a-ketoglutarate, and recent efforts to develop amino acid analogs to inhibit glutamine metabolism in cancer have been extensive. This study describes the synthesis of L-gamma-methyleneglutamic acid amides as an inhibitor and evaluates them to the cell growth of MCF-7, SK-BR-3, and MDA-MB-231 breast cancer cells within 24 or 72 h of treatment. The lead compound was well behaved in mice pharmacokinetics and had decent intraperitoneal bioavailability, moderate clearance, optimum half-life, and a high volume of distribution, unlike many reported inhibitors of glutaminolysis. Specific targets of L-gamma-methyleneglutamic acid amides, especially in the mitochondria metabolism in cancer, are being studied to develop successive generations of novel anticancer agents.

Technical Abstract: In cancer cells, glutaminolysis is the primary source of biosynthetic precursors, and recent efforts to develop amino acid analogs to inhibit glutamine metabolism in cancer have been extensive. Our lab recently discovered many L-gamma-methyleneglutamic acid amides that were shown to be as efficacious as tamoxifen or olaparib at arresting the cell growth of MCF-7, SK-BR-3, and MDA-MB-231 breast cancer cells by 24 or 72 h of treatment. None of the compounds inhibited the cell growth of benign MCF-10A breast cells. These compounds hold promise as novel therapeutics for the treatment of multiple breast cancer subtypes. Herein we report our further studies of the tert-butyl ester and ethyl ester prodrugs of these compounds, as well as of the cyclic metabolite, and tested them on the three cancer cell lines MCF-7, SK-BR-3, and MDA-MB-231. These prodrugs were observed to also suppress the growth of these cancer cells, but less in potency compared to their parent L-gamma-methyleneglutamic acid amides. Therefore, pharmacokinetic (PK) studies were performed on the lead L-gamma-methyleneglutamic acid amide (compound 5) to establish the tissue-specific distribution and other PK parameters. Notably, 5 displayed moderate exposure in the brain with a half-life of 0.71 h and good tissue distribution in the kidney and liver. The L-gamma-methyleneglutamic acid amides were then tested on head and neck cancer (HN8, HN12, HN30, and HN31) and glioblastoma (BNC3 and BNC6) cell lines and were shown to effectively suppress the growth of these cells by 24 or 72 h of treatment in a concentration-dependent manner. These results suggest broad applications of these L-gamma-methyleneglutamic acid amides in anticancer therapy.