Abstract:

In order to identify small-molecule antagonists of Methuselah (Mth), a Drosophila G-protein-coupled receptor (GPCR) involved in life-span control, a library of natural compounds was screened, and it was found that rediocide A (1), a daphnane ester from the roots of Trigonostemon reidioides and used currently for flea control, potently inhibited calcium mobilization mediated by this receptor. Compound 1 inhibited calcium mobilization in GPCRs other than Mth, indicating that the inhibitory effect was not due to receptor antagonism but rather to a more general mechanism. It was found that 1 can induce GPCR desensitization and internalization, and such effects were mediated by the activation of conventional protein kinase C.