Biochem/physiol Actions

Hypothemycin, one of the highly oxygenated analogues in the group of 14-membered resorcylic acid lactones (RAL), has minor antifungal and cytotoxic activity and exhibits an in vitro anti-malarial activity with an IC₅₀ of 2.2 µg/mL. Hypothemycin is also reported to selectively and irreversibly inhibit protein kinases that contain a conserved cysteine residue (Cys¹⁶⁶) that is located within the ATP-binding domain. Though this group accounts for less then 10% of all identified kinases, there are several targets implicated in aberrant cellular proliferation such as ERKs, MEK, FMS-like tyrosine kinase protein (FLT), and platelet-derived growth factor receptors (PDGFR). In cell culture, hypothemycin displays potent cytotoxicity against cancer cell lines that are dependent on certain activating kinase mutations. Additionally, hypothemycin demonstrates significant tumor growth inhibition in at least three separate murine xenograft models. Hypothemycin also inhibits the production of several cytokines such as IL2, IL6, IFNγ, and TNFα.