Antimutagenicity of ellagic acid against aflatoxin B₁ in the Salmonella microsuspension assay

Ellagic acid (EA) is a phenolic compound with antimutagenic and anticarcinogenic properties. It occurs naturally in some foods such as strawberries, raspberries, grapes, black currants and walnuts. In the present study, we used the Salmonella microsuspension assay to examine the antimutagenicity of EA against the potent mutagen aflatoxin B₁ (AFB₁) using tester strains TA98 and TA100, Further, we used a two-stage incubation procedure that incorporates washing the bacterial cells free of the incubation mixture after the first incubation to investigate EA and AFB₁ interaction. Three different concentrations of AFB₁ (2.5, 5 and 10 ng/tube) were tested against five different concentrations of EA for TA98 and TA100. EA significantly inhibited mutagenicity of all doses of AFB₁ in both tester strains with the addition of S9. EA alone was not mutagenic at the concentrations tested. The greatest inhibitory effect of EA on AFB₁ mutagenicity occurred when EA and AFB₁ were incubated together. Lower inhibition was apparent when the cells were first incubated with EA followed by a second incubation with AFB₁, and also when the cells were first incubated with AFB₁ followed by a second incubation with EA alone. The results of the sequential incubation studies support the hypothesis that one mechanism of inhibition could involve the formation of a chemical complex between EA and AFB₁.