Inhibition of Calcineurin and Glycogen Synthase Kinase-3β by Ricinoleic Acid Derived from Castor Oil.

Ricinoleic acid (RA) is the main fatty acid component of castor oil and was found to inhibit Ca -signal transduction pathway-mediated cell cycle regulation in a yeast-based drug screening assay. RA is expected to have antidiabetic, antiallergy, and/or anticancer properties but its target molecule is unknown. To identify a novel pharmacological effect of RA, we investigated its target molecule in the Ca -signal transduction pathway.

Kujigamberoic acid A, a carboxylic acid derivative of kujigamberol, has potent inhibitory activity against the degranulation of RBL-2H3 cells.

The aldehyde and carboxylic acid derivatives of kujigamberol were synthesized using pyridinium dichromate (PDC). The carboxylic acid derivative exhibited lower cytotoxicity and inhibited the degranulation of rat basophilic leukemia-2H3 (RBL-2H3) cells stimulated by thapsigargin more than kujigamberol. The carboxylic acid derivative was detected and isolated from the methanol extract of Kuji amber (MEKA) by the modified isolation procedure.

Isolation of a spirolactone norditerpenoid as a yeast Ca signal transduction inhibitor from Kuji amber and evaluation of its effects on PPM1A activity.

A different type of biologically active compound from Kuji amber (Late Cretaceous, Japan) before the K-Pg boundary [65 million years ago (Ma)] was isolated based on the growth-restoring activity of a mutant yeast involving Ca signal transduction. It was identified as a spirolactone norditerpenoid, (4R*, 5S*, 8R*, 9R*, 10S*)-14,15,16,19-tetranor-labdan-13,9-olide (1) from spectral analyses with high-resolution electron ionization mass spectrometry (HREIMS), 1D and 2D nuclear magnetic resonance (NMR). Although the planar structure of 1 is known as an artificial derivative from marrubiin, it was isolated as a natural product from Kuji amber and its structure was elucidated for the first time.