Alleviative effects of quercetin of Botrytis cinerea-induced toxicity in zebrafish (Danio rerio) larvae

Quercetin is a kind of flavonoid substance extensively existing in the plant, which has antioxidant, anti-inflammatory, and anti-apoptosis effects. It was reported that the higher concentration of spores present in the environment could cause abnormal development in zebrafish larvae. Therefore, this study set out to investigate whether quercetin could reduce the zebrafish larvae damage caused by Botrytis cinerea exposure as well as to examine the molecular basis for this action. The findings demonstrated that 50 μM quercetin improved the developmental dysplasia of zebrafish larvae induced by 10 2  CFU/mL Botrytis cinerea spore suspension, reduced abnormal apoptosis, enhanced antioxidant system, relieved inflammation, reshaped intestinal morphology and recovered intestinal motility . At the molecular level, quercetin decreased the transcriptional abundance of pro-apoptotic factors ( bax , p53 , caspase3 , and caspase9 ) and up-regulated the anti-apoptotic gene ( bcl-2 ) expression to reduce apoptosis. Moreover, quercetin enhanced the activities of downstream antioxidant enzymes (SOD and CAT) to clear excess ROS and MDA due to Botrytis cinerea exposure by up-regulating the expression of antioxidant genes ( nrf2 , ho-1 , sod , and cat ) in the Keap1-Nrf2 pathway. Additionally, quercetin inhibited the elevation of TNF-α by regulating the gene expression of key targets ( jak3 , pi3k , pdk1 , akt , and ikk2 ) and the content of major proteins NF-κB (P65) and IκB in the NF-κB pathway. In conclusion, this work enriched the contents of the biological research of Botrytis cinerea and provided a new direction for the drug development and targeted therapy of quercetin.