A Phenylpropanoid Glycoside as a Calcineurin Inhibitor Isolated from Magnolia obovata Thunb

To identify plant-derived cell signaling inhibitors with antifungal properties, a twocomponent screening system using both wild-type Cryptococcus neoformans and a calcineurin mutant was employed owing to their counter-regulatory actions on the Hog1 mitogenactivated protein kinase and calcineurin pathways. Of the 2,000 plant extracts evaluated, a single bioactive compound from M. obovata Thunb. was found to act specifically on the calcineurin pathway of C. neoformans. This compound was identified as magnoloside A, and had potent antifungal activities against various Cryptococcus strains with minimum inhibitory concentration values ranging from 1.0 to 4.0 μg/ml.