Time-dependent increase of plasma cGMP concentration followed by oral EGCG administration in mice

Abstract

Epigallocatechin 3-O-gallate (EGCG), the major catechin in green tea, exerts several beneficial effects in vivo. A previous study showed that cyclic guanosine monophosphate (cGMP) as a cellular second messenger has been shown to be an important mediator of the effects of EGCG. In general, long-term animal experiments are required to evaluate the functionality of phytochemicals such as EGCG. Thus, it might be beneficial to establish a marker for short-term evaluation of functional phytochemicals. In this study, the use of the plasma cGMP level was evaluated as a surrogate marker for the functional effectiveness of EGCG. Blood samples were collected from 6-wk-old C57BL/6J mice from 1 to 8 h after oral administration of EGCG (30 or 100 mg/kg). The upregulation of plasma cGMP levels elicited by the oral EGCG administration was evaluated. Additionally, it was confirmed that EGCG induced the expressions of intracellular Toll interacting protein (Tollip), which is mainly controlled by a cGMP signal in the spleen. These data indicated that the plasma cGMP levels could be a screening marker for the effect of EGCG.