The antimicrobial mechanism of totarol was studied using Pseudomonas a
eruginosa IFO 3080. This diterpene inhibited oxygen consumption and re
spiratory-driven proton translocation in whole cells, and oxidation of
NADH in membrane preparation. NADH-cytochrome c reductase was inhibit
ed by totarol while cytochrome c oxidase was not. NADH-DPIP reductase
and NADH-CoQ reductase were also inhibited. The site of respiratory in
hibition of totarol was thought to be near CoQ in the bacterial electr
on transport chain.