The anaphylatoxin C3a induces a range of responses by activating its G protein-coupled receptor, C3aR, resulting in calcium mobilization. SB 290157 is a non-peptide antagonist of C3aR, competitively blocking C3a binding with an IC50 value of 200 nM. It potently inhibits a wide variety of C3a-induced responses in cells, including calcium increase in human neutrophils (IC50 = 28 nM) and ATP release from guinea pig platelets (IC50 = 30 nM). SB 290157 is also effective in vivo, reducing inflammation in a variety of animal models. It also significantly reduces or reverses diet-induced obesity in rats and accelerates the mobilization of hematopoietic progenitor cells to the peripheral blood in mice. Notably, SB 290157 has C3aR agonist activity in some cell systems.
