Synthetic and Biocatalytic Methods for the Chemoenzymatic Production of Novel Cryptophycin Anticancer Agents.

[摘要] The cryptophycin family of cyanobacterial peptolides contains exceptionally potent antimitotic anticancer agents. Active at levels significantly lower than currently approved cancer therapies, synthetic cryptophycin 52 was also effective against multi-drug resistant cancers. Phase II clinical trials revealed minor peripheral neurotoxicity, however, making synthetic derivatization a priority for the development of safe, effective cryptophycins for the treatment of cancer. Specifically, incorporation of heterocycles on unit A of cryptophycin was proposed to increase the solubility and stability, as well as reduce toxicity of the parent drugs. To this end, an efficient and divergent synthetic route to unit A analogues was developed and optimized for the production of a diverse library of heterocyclic functionality. Incorporation with units B, C, and D yielded fully elaborated, SNAc-thioester bound seco-cryptophycins as substrates for macrocyclization. Cryptophycin thioesterase (CrpTE) activity was reconstituted in vitro and used to demonstrate impressive inherent flexibility for a suite of heterocyclic substrates. CrpTE was then optimized for activity and displayed little preference for reaction temperature, buffer pH, or DMSO concentration.Incredibly, CrpTE was active at up to 50% DMSO and in a variety of organic solvents. In fact, a novel cosolvent system of 20% diglyme with 1% MCD more than doubled CrpTE conversion with a natural substrate mimic and proved to be an effective strategy for the chemoenzymatic cyclization of the 2-pyridyl derivatized cryptophycin 500. Joined with the complementary heterocyclic substrate flexibility of cryptophycin epoxidase (CrpE), a powerful method now exists to produce unique cryptophycins in a campaign to access better anticancer agents. This chemoenzymatic method should also provide a means to construct affinity probes for mechanism of action studies and interrogation of CrpTE and CrpE active site architecture.

[发布机构] University of Michigan

[效力级别] Cancer

[关键词] Medicinal Chemistry;Cancer;Cryptophycin;Natural Products;Chemoenzymatic;Chemistry;Science;Medicinal Chemistry