RK-682 (150627-37-5) is a protein tyrosine phosphatase inhibitor (IC₅₀'s = 54 7mu;M for CD45, 2.0 μM for VHR; did not inhibit cdc25B) originally isolated from the fermentation of Streptomyces sp. 88-682.¹ Inhibits cell cycle at G₁/S. RK-682 has also been shown to inhibit PLA2 (IC₅₀ = 16 μM)², HIV-1 protease (IC₅₀ = 84 μlM)³, and heparanase (IC₅₀ = 17 μM)⁴. Natural RK-682 (R-isomer) and synthetic racemic material have identical phosphatase activity.⁵ Care should be taken when using RK-682 in the presence of metal salts - because it readily forms metal complexes that affects its phosphatase inhibitory activity.⁶ RK-682 has been identified as a potential promiscuous inhibitor.⁷

References/Citations
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7) Carneiro et al. (2015), Is RK-682 a promiscuous enzyme inhibitor? Synthesis and in vitro evaluation of protein tyrosine phosphatase inhibition of racemic RK-682 and analogues; Eur. J. Med. Chem., 97 42