Mechanism of action of atpenin B on Raji cells

Atpenin B, a new antifungal antibiotic produced by Penicillium sp. FO-125, inhibited the growth of Raji cells (IC50, 30 microM). The incorporation of [14C]leucine and [3H]thymidine into Raji cells was inhibited by atpenin B with IC50 values of 0.10 and 0.12 microM, respectively. The incorporation of [14C]palmitate into the cells was not inhibited but its incorporation into lipid fractions was inhibited by atpenin B (IC50, 0.13-0.24 microM). Studies on the site of atpenin B action demonstrated that atpenin B decreases the cellular adenosine 5'-triphosphate (ATP) level in Raji cells with IC50 value of 0.020 microM, suggesting the inhibition of ATP-generating system by atpenin B.