Further researches upon the inhibiting action of lycorine on ascorbic acid biosynthesis.
Lycorine, an alkaloid extracted from Amarillidaceae, strongly inhibits the "in vivo" conversion of galactono-gamma-lactone to ascorbic acid. Lycorine seems to act as a non-competitive inhibitor on galactono-gamma-lactone oxidase, because the alkaloid rapidly forms a stable bound with the enzyme. In fact, a short incubation period with 50 microM lycorine gets a high inhibitory effect that persists when the alkaloid is removed from the incubation medium. Considering that lycorine induces scurvy-like symptoms in ascorbic acid-synthesising animals, it is reasonable to suppose that in both plants and animals lycorine inhibits the last step in the biosynthetic pathway leading from sugar to ascorbate.
De Gara
L
L
Istituto di Botanica, Università di Bari.
Tommasi
F
F
D000490:Allium / Q000378:metabolism; D047151:Amaryllidaceae Alkaloids; D001205:Ascorbic Acid / Q000096:biosynthesis*; D003864:Depression, Chemical; D007887:Fabaceae / Q000378:metabolism; D010617:Phenanthridines / Q000494:pharmacology*; D010940:Plant Proteins / Q000037:antagonists & inhibitors*; D010946:Plants, Medicinal; D013401:Sugar Alcohol Dehydrogenases / Q000037:antagonists & inhibitors*
D047151:Amaryllidaceae Alkaloids; D010617:Phenanthridines; D010940:Plant Proteins; D013401:Sugar Alcohol Dehydrogenases; C020550:L-galactonolactone oxidase; C015330:lycorine; D001205:Ascorbic Acid