Efficient Synthesis, Stability-Guided Optimization and Anticancer Evaluation of Bee Venom Peptide Melittin

Abstract

Natural cytotoxic peptides (NCPs) are emerging sources of novel anticancer chemotherapeutics. Especially, Melittin, which is the major component of bee venom and the first-in-class NCP, has been considered as a promising anticancer scaffold. Nevertheless, as a classical linear, cationic, amphipathic, and membrane-lytic peptide, Melittin may be easily degraded by proteases, suffering from poor stability, moderate anticancer durability, and severe hemolysis. In this study, applying the terminal modification and hybridization strategies, ten Melittin-based derivatives were designed, synthesized, and investigated for their anticancer potential. The robust and economic synthetic method, in vitro anticancer efficiency, time-kill kinetics, serum stability, anti-migration activity, hemolysis effects, and anticancer mechanism were explored. As expected, the Melittin-based derivatives exhibited highly potent cytotoxicity against all six tested cancer cell lines. In particular, compared with natural Melittin, the derived peptides LJ-5 containing both N-terminal acetylation and C-terminal hydrazidation, and LJ-6, the methotrexate MTX-GFLG-Melittin conjugate exhibited significantly improved proteolytic stability, more durable anticancer efficiency, higher anti-migration activity, as well as reduced hemolysis effects. Besides, it was further verified that LJ-5 and LJ-6 could efficiently disrupt the integrity of cancer cell membrane, localize to the mitochondria and rapidly reduce the mitochondrial membrane potential of cancer cells. Collectively, the economic synthetic method and stability-guided optimization were conducted on Melittin, affording hydrolysis-resistant LJ-5 and LJ-6 that may serve as anticancer candidates and useful references for further optimizations of cytotoxic peptides.

Note:
Funding declaration: This study was supported by the National Natural Science Foundation of China (Grant No. 22177058), the Taishan Scholar Program of Shandong Province (Grant No. tsqn202312168), the Open Projects Fund of NMPA Key Laboratory for Quality Research and Evaluation of Carbohydrate-based Medicine (Grant No. 2024QRECM02) and the Natural Science Foundation of Shandong Province (Grant No. ZR2024YQ061).

Conflict of Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Keywords: Anticancer activity, Bee venom peptide, Natural cytotoxic peptides, DIC/Oxyma, Melittin, Methotrexate