槲皮素抑制黄曲霉毒素产生的机制初探

Inhibition Effect of Quercetin on Aflatoxin B1 Production

摘要:

研究发现茶叶中的茶多酚单体普遍具有抑制黄曲霉毒素B1（AFB1）产生的活性，而槲皮素的抑毒活性要高于等浓度下儿茶素类茶多酚。为了解槲皮素抑制黄曲霉毒素产生的分子机制，对黄曲霉菌的抗氧化系统、毒素产生的相关基因进行了分析。试验结果显示槲皮素处理能后降低黄曲霉菌内的ROS水平，降低MDA含量。RT-PCR结果证实槲皮素能够激活抗氧化系统转录因子Yap1，导致黄曲霉体内的抗氧化酶系统活性的增加，POD、CAT、SOD都得到了显著的提高，这很可能是槲皮素抑制AFB1产生的关键因素；槲皮素能同时下调AflR与AflS的表达，而AflS能够通过结合AflR调控产毒基因的表达，这很可能是槲皮素抑制AFB1产生的核心分子机制，这种机制也与其激活抗氧化系统缓解菌体内氧化胁迫的作用相对应。以上结果表明槲皮素作为一种高效的黄曲霉毒素合成抑制剂，将对提高食品安全保障具有较高的应用价值。

Abstract:

Many polyphenol monomers could inhibit aflatoxin B1 production and Quercetin had higher inhibitory activity than other catechin polyphenols.To explore the inhibition effect of quercetin on aflatoxin B1 production, the antioxidant system of Aspergillus flavus was monitored and the toxin genes express after quercetin treatment were analyzed. The results showed that quercetin treatment decreased the ROS and MDA concentration, confirming that this treatment could alleviate the oxidative stress of Aspergillus flavus. RT-PCR result showed that quercetin was able to activate the transcription factor Yap1 in antioxidant system to increase antioxidant enzyme activity, such as POD, COT and SOD activity. This induction may be a key factor for quercetin inhibition on AFB1. Quercetin downregulated the expression of AflRand AflS And AflS could regulate toxin production by combining AflR expression gene, which is possibly the key mechanism of the inhibition effect of quercetin on AFB1. This was also associated with activation of antioxidant systems in easing the fungi oxidative stress in vivo. In the case of AflR downward, the toxin gene expression was inhibited. Hence, quercetin can be employed as an efficient aflatoxin synthesis inhibitor with great application potential.