Ca²⁺-Signal Transduction Inhibitors, Kujiol A and Kujigamberol B, Isolated from Kuji Amber Using a Mutant Yeast

A podocarpatriene and a labdatriene derivative, named kujiol A [13-methyl-8,11,13-podocarpatrien-19-ol (<b>1</b>)] and kujigamberol B [15,20-dinor-5,7,9-labdatrien-13-ol (<b>2</b>)], respectively, were isolated from Kuji amber through detection with the aid of their growth-restoring activity against a mutant yeast strain (<i>zds1</i>Δ <i>erg3</i>Δ <i>pdr1</i>Δ <i>pdr3</i>Δ), which is known to be hypersensitive with respect to Ca²⁺-signal transduction. The structures were elucidated by spectroscopic data analysis. Compounds <b>1</b> and <b>2</b> are rare organic compounds from Late Cretaceous amber, and the mutant yeast used seems useful for elucidating a variety of new compounds from Kuji amber specimens, produced before the K–Pg boundary