β-Amanitin is a cyclic peptide toxin in the poisonous Amanita phalloides mushroom. β-Amanitin inhibits inhibits eukaryotic RNA polymerase II and III. β-Amanitin inhibits protein synthesis. β-Amanitin can be used as a cytotoxic component of antibody-drug conjugates (ADCs)^[1][2]. In Vitro: β-Amanitin (0.01-100 µg/mL; 36 hours) shows toxicity in MCF-7 cells, and the rates of cell viability are calculated as 52%, 62%, 84%, 86%, and 91% at concentrations of 100, 10, 1, 0.1, and 0.01 µg/mL, respectively^[2].
β-Amanitin shows a great inhibition of protein synthesis at both concentrations (10 µg/mL and 1 µg/mL) in MCF-7 cells for 24 hours^[2].