Inhibitory effects of foods and polyphenols on activation of aryl hydrocarbon receptor induced by diesel exhaust particles.

: The toxicity of endocrine disrupters is involved in the activation of the aryl hydrocarbon receptor (AhR). We examined the toxicity of diesel exhaust particles (DEPs) using the Ah immunoassay (Ah-I) to study the inhibitory effects of various foods and polyphenols on DEP-induced AhR activation. The toxicity equivalent of DEP was 6,479 +/-58 ng dioxin toxicity equivalent/g (DEQ/g). The relationship between DEP dose and AhR activation was linear up to 27.8 microg/ml. Ginkgo biloba extract (GBE) had the strongest inhibitory effect on DEP-induced AhR activation. Quercetin, a major polyphenol in onions, and GBE showed a strong inhibitory effect. These results show that the DEP-induced AhR activation can be assessed using Ah-I and that the assay is suitable for determining the dioxin toxicity equivalent of DEP. In addition, Ah-I is also effective for screening food and its components that inhibit DEP-induced AhR activation.