Precursor-Directed Biosynthesis of Neoantimycin Derivatives with Selective Cytotoxicity

Area of Science:

• Natural Product Chemistry
• Medicinal Chemistry
• Molecular Biology

Background:

• Neoantimycins are complex natural products with potential anticancer activities.
• Targeting specific mutations, like K-ras in colorectal cancer, is a key strategy in cancer therapy.
• Developing novel therapeutics for drug-resistant or mutation-driven cancers remains a critical need.

Purpose of the Study:

• To synthesize and characterize novel neoantimycin derivatives using a precursor-directed biosynthesis approach.
• To evaluate the cytotoxic activity of these new derivatives against cancer cell lines, particularly those with K-ras mutations.
• To elucidate the structure and determine the absolute configuration of the newly discovered compounds.

Main Methods:

• Precursor-directed biosynthesis using *Streptomyces conglobatus* RJ2.
• Structure elucidation via Nuclear Magnetic Resonance (NMR) and High-Resolution Electrospray Ionization Mass Spectrometry (HRESIMS).
• Determination of absolute configuration using advanced Marfey's method, Mosher's analysis, and Electronic Circular Dichroism (ECD) analysis.
• In vitro cytotoxicity assays to determine half-maximal inhibitory concentration (IC50) values.

Main Results:

• Seven new neoantimycin derivatives (compounds 1-7) were successfully synthesized and isolated.
• The structures and absolute configurations of the new derivatives were rigorously determined.
• Compounds 1-7 exhibited selective and potent cytotoxicity against colorectal cancer cells harboring the K-ras mutation, with IC50 values in the nanomolar to low micromolar range (40 nM - 3.5 μM).

Conclusions:

• The precursor-directed biosynthesis strategy is effective for generating novel neoantimycin analogs.
• The newly synthesized neoantimycin derivatives demonstrate promising selective anticancer activity against K-ras-mutated colorectal cancer.
• These findings highlight the potential of these compounds as leads for developing targeted therapies for K-ras-driven colorectal cancers.