Rhein-13C4 is intended for use as an internal standard for the quantification of rhein by GC- or LC-MS. Rhein is an anti-inflammatory anthraquinone found in rhubarb and is the bioactive derivative of its prodrug diacerein . At 10 μM, rhein inhibits IL-1β signaling, suppressing signaling through NF-κB, and reduces the expression of the matrix metalloproteases MMP-1 and MMP-13.1 It inhibits IKKβ (IC50 = 11.8 μM), decreasing iNOS and IL-6 expression in LPS-stimulated macrophages but paradoxically increasing TNF-α, IL-1β, and HMBG1 expression.2 Rhein shows efficacy against pancreatic fibrosis, chronic pancreatitis, and hyperglycemia-induced pancreatic β-cell apoptosis.3,4 It also inhibits angiogenesis of breastcancer cells under normoxic and hypoxic conditions.5
CB-1158-analog, also known as Numidargistat-analog and INCB01158-analog, is a potent and orally active arginase inhibitor with IC50=89 nM) . CB-1158 blocked myeloid cell-mediated suppression of T cell proliferation in vitro and reduced tumor growth in multiple mouse models of cancer, as a single agent and in combination with checkpoint blockade, adoptive T cell therapy, adoptive NK cell therapy, and the chemotherapy agent gemcitabine. CB-1158 increased tumor-infiltrating CD8+ T cells and NK cells, inflammatory cytokines, and expression of interferon-inducible genes. CB-1158 may be potentially useful in renal cell cancer, breastcancer, non-small cell lung cancer, acute myeloid leukemia, and other tumor types where arginase-secreting MDSCs are known to play an immunosuppressive role. (see ADDITIONAL INFORMATION in this web page for CB-1158 structure confusion).