DESCRIPTION Hypothemycin, a fungal polyketide, is a multikinase inhibitor with Kis of 10/70 nM, 17/38 nM, 90 nM, 900 nM/1.5 ¦ÌM, and 8.4/2.4 ¦ÌM for VEGFR2/VEGFR1, MEK1/MEK2, FLT-3, PDGFR¦Â/PDGFR¦Á, and ERK1/ERK2, respectively[1][2].

DESCRIPTION Hypothemycin, a resorcylic acid lactone antibiotic, was identified as active in a screen for inhibitors of T cell activation. It was found to inhibit the proliferation of mouse and human T cells stimulated with anti-CD3 mAb + PMA and of human PBMC stimulated with anti-CD3 mAb alone. This inhibition was partially reversed by exogenous IL-2 indicating that it is not due to non-specific toxicity. Hypothemycin potently suppressed the production of IL-2 (IC50: 9 nM) but affected IL-2-induced proliferation to a lesser extent (IC50: 194 nM). Hypothemycin also inhibited IL-6, IL-10, IFN-gamma and TNF-alpha production. By contrast, it markedly enhanced the production of IL-4, IL-5 and IL-13. These effects were seen both at the mRNA and protein secretion levels. Analysis of the effect of hypothemycin on CD69 induction suggested that it disrupts calcineurin-independent rather than calcineurin-dependent signaling. Furthermore, hypothemycin was able to inhibit the phosphorylation of ERK1/2 induced by PMA treatment of T cells. Therefore, hypothemycin represents an inhibitor of T cell activation with a novel mode of action and unique modulatory activity on cytokine production. (BOC Sciences Bioactive Compounds)