Bacteriostatic activities and metal chelation of kojic acid analogs.

Abstract

The relationship between structure and activity in bacteriostasis was compared to the relationship between structure and reactivity in metal chelate formation for various kojic acid analogs. The metal chelating property with Cu2+ and Cd2+ was closely related to the acid dissociation constant. Since structure-activity analyses showed that the neutral molecule is the active form, and since the pK_??_ value as the electronic parameter is related to the activity only for the neutral molecule but not for the ionized form, it was postulated that metal chelate formation is not significant for manifestation of the bacteriostatic activity of this series of compounds. This postulation was confirmed in experiments under conditions in which the metal was depleted or excessive. The bacteriostatic activity of kojic acid analogs against such bacteria as S. aureus 209 P, E. coli K-12 and Ps. fluorescens was neither retarded nor enhanced.