Differential activation of protein kinase C isoforms by euxanthone, revealed by an in vivo yeast phenotypic assay

The protein kinase C (PKC) modulatory effects of euxanthone, isolated from the wood of Cratoxylum maingayi, on isoforms alpha, betaI, delta, eta and xi were characterised using an alternative in vivo yeast phenotypic assay. The present study shows that euxanthone can activate isoforms alpha, betaI, delta, eta and xi, being more effective on PKC-betaI, -delta, -eta and -xi than the established PKC activators used (the phorbol ester PMA and arachiclonic acid for PKC-xi). Furthermore, euxanthone presents differences on its potency towards individual PKC isoforms, showing a remarkable selectivity for PKC-xi. These results can help to clarify the molecular basis of the euxanthone-mediated effects.