Computation-Enhanced Structure Elucidation of Cyclopropane-Containing Polyketides Ikeiamides A-M.

Area of Science:

• Natural Product Chemistry
• Marine Biology
• Computational Chemistry

Background:

• Marine cyanobacteria are a prolific source of structurally diverse natural products.
• Polyketides, including cyclopropane-containing variants, often exhibit unique biological activities.
• Structural elucidation of complex natural products can be challenging, especially when compounds are scarce or unstable.

Purpose of the Study:

• To isolate and characterize novel polyketides from a marine cyanobacterium.
• To demonstrate the effectiveness of computational chemistry in elucidating the structures of challenging natural products.
• To report the discovery of Ikeiamides A-M.

Main Methods:

• Isolation of compounds from *Caldora* sp. marine cyanobacteria.
• Extensive application of computational chemistry, including DP4 and CP3 analyses.
• Spectroscopic data analysis for structural elucidation.

Main Results:

• Thirteen cyclopropane-containing polyketides, named Ikeiamides A-M (1-13), were isolated.
• Nine of the thirteen compounds were obtained in trace quantities (<1 mg).
• The structures of all thirteen compounds were successfully elucidated using computational methods despite their instability and scarcity.

Conclusions:

• Computational chemistry, specifically DP4 and CP3, is highly effective for elucidating the structures of scarce and labile natural products.
• The study expands the known diversity of polyketides from marine cyanobacteria.
• Ikeiamides A-M represent a new class of cyclopropane-containing polyketides.