Quercetagetin Ameliorates Heat Stress-Induced Intestinal Damage via Oxidative Stress, Inflammation and Gut Microbiota in Mice.

Quercetagetin (QG), a principal flavonol from marigold (Tagetes erecta L.), is recognized for its potent antioxidant properties. However, its efficacy in mitigating intestinal injury under heat stress (HS) conditions remains unclear. We investigated the protective effects of QG using a mouse model of HS (41 °C, 70% humidity). Mice received oral QG (100 mg/kg/day) or saline for seven consecutive days before and during HS exposure. We assessed jejunal histopathology, oxidative stress markers, inflammatory cytokines, gene expression, and gut microbiota composition via 16S rRNA sequencing. QG supplementation significantly ameliorated HS-induced jejunal damage. It enhanced the activities of superoxide dismutase (SOD) and catalase (CAT) while reducing malondialdehyde (MDA) and pro-inflammatory cytokines (IL-1β, IL-6, TNF-α). QG downregulated the mRNA expression of heat shock proteins (Hsp70, Hsp90) and upregulated antioxidant-related genes (SOD1, GPX4, CAT, NQO1, Nrf2). Furthermore, QG preserved intestinal barrier integrity by upregulating tight junction proteins (Occludin, Zo-1, Claudin). 16S rRNA analysis revealed that QG significantly reshaped the gut microbiota, marked by an increased relative abundance of Lactobacillus and a decrease in potentially harmful taxa such as Allobaculum, Oscillibacter, and Colidextribacter. QG effectively alleviates HS-induced intestinal injury by enhancing antioxidant capacity, suppressing inflammation, and modulating the gut microbiota. These findings provide a scientific basis for the potential application of QG as a functional feed additive to improve animal health under heat stress conditions.