SB290157 trifluoroacetate is a potent and selective antagonist of the C3a receptor, with an IC50 of 200 nM.

C3a:200 nM

SB 290157 is a competitive antagonist of 125I-C3a radioligand binding to rat basophilic leukemia-2H3 cells expressing the human C3aR (RBL-C3aR, IC50 of 200 nM). SB 290157 blocks C3a-induced C3aR internalization in a concentration-dependent manner and C3a-induced Ca2+ mobilization in RBL-C3aR cells and human neutrophils (IC50s of 27.7 and 28 nM, respectively). SB 290157 is selective for the C3aR in that. SB 290157 also inhibits C3a-induced Ca2+ mobilization of RBL-2H3 cells expressing the mouse and guinea pig C3aRs. It potently inhibits C3a-mediated ATP release from guinea pig platelets and inhibits C3a-induced potentiation of the contractile response to field stimulation of perfused rat caudal artery[1].

SB 290157 effectively inhibits neutrophil recruitment in a guinea pig model of LPS-induced airway neutrophilia and reduces paw edema in a rat model of adjuvant-induced arthritis. This antagonist demonstrates a capacity to decrease joint swelling, achieving approximately 50% inhibition at a concentration of 30 mg/kg, but only at the 3-hour mark. Additionally, it significantly lowers C3 levels at 3 hours post-administration, indicating complement consumption compared to naive mice. An increase in C3 activation correlates with the graded concentration of anti-OVA pAb, further showcasing its biological activity (1, 2).