Inhibition of melanogenesis by 5,7-dihydroxyflavone (chrysin) via blocking adenylyl cyclase activity

Due to its multiple biological activities, 5,7-dihydroxyflavone (chrysin) in propolis has gained attention as potentially useful therapeutics for various diseases. However, the efficacy of chrysin for the use of dermatological health has not been fully explored. To clarify the action mechanism of the skin protecting property of chrysin, we firstly investigated the molecular docking property of chrysin on the mammalian adenylyl cyclase, which is the key enzyme of cAMP-induced melanogenesis. We also examined the involvement of chrysin in alpha-MSH and forskolin-induced cAMP signaling within a cell based assay. In addition, we inquired into the inhibitory effect of chrysin on melanogenesis and found that the pretreatment with chrysin inhibited the forskolin-induced melanin contents significantly without annihilating the cell viability. These results strongly suggest that chrysin directly inhibits the activity of adenylyl cyclase, downregulates forskolin-induced cAMP-production pathway, consequently inhibiting melanogenesis. Thus, chrysin may also be used as an effective inhibitor of hyperpigmentation.