Roridin E is a macrocyclic trichothecene mycotoxin that has been found in M. verrucaria. It inhibits the receptor tyrosine kinases FGFR3, IGF-1R, PDGFRβ, and TrkB (IC50s = 0.4, 0.4, 1.4, and 1 μM, respectively). Roridin E induces cytotoxicity in multiple breast cancer cell lines (IC50s = 0.02-0.05 nM) and inhibits proliferation in a panel of additional cancer cell lines (IC50s = P. falciparum (EC50 = 0.15 ng/ml), induces phytotoxicity in duckweed and kudzu, and is toxic to mice (LD50 = 10 mg/kg, i.p.). Roridin E is also produced by the plant B. coridifolia, which is associated with livestock poisoning in South America.