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.