PSB-603

PSB-603 is an antagonist of the adenosine A_2B receptor (K_i = 0.553 nM).¹ It is selective for adenosine A_2B over A₁, A_2A, and A₃ receptors (K_is = >10,000 nM). It reduces intracellular calcium concentrations in Jurkat T cells expressing the human A_2B receptor (IC₅₀ = 1.13 nM). PSB-603 reduces Zika viral plaque formation (IC₅₀ = 43.8 nM) without affecting cell viability of A549 cells when used at concentrations up to 1 µM.² In vivo, PSB-603 (0.25 µg/head, i.p.) delays tumor growth and reduces tumor volume and the number of pulmonary metastases in the B16 mouse model of melanoma via inhibition of induction of regulatory T cells.³

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1. Borrmann, T., Hinz, S., Bertarelli, D.C., et al. 1-alkyl-8-(piperazine-1-sulfonyl)phenylxanthines: Development and characterization of adenosine A2B receptor antagonists and a new radioligand with subnanomolar affinity and subtype specificity. J. Med. Chem. 52(13), 3994-4006 (2009).

2. Micewicz, E.D., Khachatoorian, R., French, S.W., et al. Identification of novel small-molecule inhibitors of Zika virus infection. Bioor. Med. Chem. Lett. 28(3), 452-458 (2018).

3. Kaji, W., Tanaka, S., Tsukimoto, M., et al. Adenosine A2B receptor antagonist PSB603 suppresses tumor growth and metastasis by inhibiting induction of regulatory T cells. J. Toxicol. Sci. 39(2), 191-198 (2014).