Inhibitory effect of biochanin a on cAMP level in HEK293 cells

Biochanin A is a flavonoid in red clover, soy, and peanuts. Although biochanin A exert various biological functions such as antihyperglycemic, apoptotic, and anti-inflammatory activities, little is known about the roles of biochanin A on cAMP level in vitro system. As adenylyl cyclase (AC) and cAMP signal transduction plays crucial roles in proliferation, perception, and contraction of muscle in response to various stimuli, searching for regulators of AC-cAMP pathway is a promising tactic for clinical applications. AC is activated by binding of ligands to their G protein-coupled receptors and leads to changes of cAMP and Ca²⁺ levels. PKA, one of cAMP target, is then activated and stimulates several transcription factors influencing gene expressions. In addition, Ca²⁺ in cytosol changes plasma membrane potential and subsequently transmission of electric signals to the brain. Before investigating biological functions in AC-cAMP pathway, screening molecules regulating AC-cAMP pathway is first step. Here, we demonstrated that biochanin A synergistically increase the cAMP level and the phosphorylation of PKA, a downstream target of cAMP in HEK cells pretreated with forskolin, a stimulator of AC. Conversely, chloroquine suppresses the forskolin-induced increase of cAMP and phosphorylation of PKA. These results suggest that some molecules found in natural products play biological functions and might be applicable in clinical use.