CD38 inhibitor 3 (compound 1) is a potent CD38 inhibitor ( IC 50 =11 nM). CD38 inhibitor 3 can promote mitochondrial biogenesis, reduce lactate levels, and increase NAD+ content and Nrf2 expression. In a model of mitochondrial myopathy, CD38 inhibitor 3 increases muscle contraction/development and improves exercise tolerance in Pus1 -/- mice.