Antimycin A2 is a homologue of the antimycin complex, first resolved from antimycin A1 in 1959. Antimycin A2, like all antimycins, is a potent inhibitor of respiration by inhibiting the oxidation of ubiquinol to ubiquinone. Antimycin A2 exhibits broad biological activity as an antifungal, anthelmintic, insecticidal, antiviral and antitumor active. Lack of availability of the individual antimycin components has hindered greater understanding of the common and unique molecular targets of the components of the antimycin complex.