title: Flavonoid inhibitors of trypsin and leucine aminopeptidase: a proposed mathematical model for IC50 estimation.
abstract: The inhibitory behavior of flavonoids against trypsin and leucine aminopeptidase followed sigmoidal curves similar to those of any dose-biological response relationship. Statistical analysis using several mathematical equations showed that the relationship may be expressed by a logistic equation, which yielded a high correlation between the experimental data and the predicted results, together with an objective criterion for estimating the IC50 value. Flavones and flavonols exhibited a strong inhibitory effect on trypsin; the presence of hydroxyl groups at positions C-5 and C-7 in ring A is necessary for inhibition of the enzyme, while the simultaneous presence of free hydroxyl groups at positions C-3' and C-4' enhances the inhibitory activity. Inhibition of leucine aminopeptidase by flavonoids does not require 5,7-hydroxylation, but dihydroxylation at C-3' and C-4' and a double bond at positions C-2, C-3 are essential for this activity.
authors.affiliation: Department of Nutrition and Food Sciences, University of Alcalá de Henares, Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Parellada
authors.forename: M
authors.initials: M
authors.lastname: Guinea
mesh_terms: D005419:Flavonoids / Q000494:pharmacology*; D007700:Kinetics; D007931:Leucyl Aminopeptidase / Q000037:antagonists & inhibitors*; D008954:Models, Biological; D012044:Regression Analysis; D013329:Structure-Activity Relationship; D014361:Trypsin Inhibitors / Q000494:pharmacology*
chemical_list: D005419:Flavonoids; D014361:Trypsin Inhibitors; D007931:Leucyl Aminopeptidase