Reactivity of glutathione with alpha, beta-unsaturated ketone flavouring substances.
The relative reactivities of a number of alpha, beta-unsaturated ketones used as flavourings were determined using glutathione as the nucleophile. Monosubstitution at the beta-position of the alpha, beta-unsaturated system impeded nucleophilic addition by approximately 1000 times. Beta-Disubstitution reduced reactivity by more than 100,000 times. Endocyclic alpha, beta-unsaturated ketones were generally less reactive than alicyclic analogues. By way of comparison, the most reactive flavouring investigated, 2-octene-4-one, was consumed by glutathione about 700 times less rapidly than was methylvinyl ketone. Methylvinyl ketone was found to condense with guanylic acid 240,000 times more slowly than with glutathione. It is concluded that alpha, beta-unsaturated ketones used as flavourings generally possess low electrophilicity.
Portoghese
P S
PS
Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis 55455.
Kedziora
G S
GS
Larson
D L
DL
Bernard
B K
BK
Hall
R L
RL
D002074:Butanones / Q000378:metabolism; D005421:Flavoring Agents / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007659:Ketones / Q000378:metabolism*; D007700:Kinetics; D008956:Models, Chemical; D012044:Regression Analysis; D013329:Structure-Activity Relationship
D002074:Butanones; D005421:Flavoring Agents; D007659:Ketones; C057920:3-buten-2-one; D005978:Glutathione