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J Nat Prod. 1995 Jun;58(6):823-9.

Flavonoid inhibitors of trypsin and leucine aminopeptidase: a proposed mathematical model for IC50 estimation.

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Department of Nutrition and Food Sciences, University of Alcalá de Henares, Madrid, Spain.


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.

[Indexed for MEDLINE]

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