Inhibition of galactonolactone dehydrogenase activity by lycorine

Abstract

Galactonolactone dehydrogenase, a mitochondrial enzyme catalyzing the last step in ascorbate biosynthesis, is strongly inhibited by lycorine. A concentration of 10 microM of the alkaloid fully inhibits the activity of the enzyme. The high sensitivity of this enzyme to lycorine supports the hypothesis that the lycorine specifically inhibits ascorbate biosynthesis and that all the other metabolic responses to lycorine treatment depend on this primary inhibition of ascorbate biosynthesis.