Kagimminols A and B, Cembrene-Type Diterpenes from an sp. Marine Cyanobacterium.

Kagimminols A () and B (), new cembrene-type diterpenoids, were isolated from an sp. marine cyanobacterium. By combining DP4 analysis with an efficient NMR chemical shift calculation protocol, we clarified the relative configurations of and without consuming precious natural products. We determined the absolute configurations by a comparison of theoretical electronic circular dichroism (ECD) spectra with experimental spectra, and the absolute configuration of was verified experimentally. Finally, we found that and showed selective growth-inhibitory activity against the causative agent of human African trypanosomiasis. This study exemplifies that computational chemistry is an efficient tool for clarifying the configurations of natural products possessing tautomers in equilibrium.