Results: 3MCG significantly reduced CO2 production from acetate (30%) and the activity of complex II-III (35%). 3MCG also inhibited the activities of mitochondrial creatine kinase (mCK) (65%) and Na+, K±ATPase (45%). Furthermore, antioxidants attenuated or fully prevented the effect of 3MCG on the activities of mCK and Na+, K±ATPase, suggesting the involvement of reactive species on these inhibitory effects.