4-Nitrobenzoate inhibits coenzyme Q biosynthesis in mammalian cell cultures.

Coenzyme Q (Q) is an electron transporter in the respiratory chain and a lipid-soluble antioxidant that decreases in humans with age. Here we show that 4-nitrobenzoate inhibited 4-hydroxybenzoate:polyprenyl transferase (Coq2) in a competitive manner and dose-dependently decreased Q in mammalian cells without accumulation of Q intermediates. As 4-nitrobenzoate neither interfered with mitochondrial respiration nor induced oxidative stress, it should prove a valuable tool for studies on both Q deficiency and Q supplementation.