Orally Administered Neohesperidin (Neo) Alleviates Lipopolysaccharide-Induced Mastitis by Suppressing TLR4/NF-κB and Activating AMPK/Nrf2/HO-1 Signaling, and Regulating Intestinal Flora Structure

The impairment of the blood-milk barrier (BMB) during mastitis severely compromises breastfeeding efficacy, highlighting an urgent need for effective nonantibiotic interventions. Natural anti-inflammatory and traditional Chinese medicine (TCM) compounds have thus garnered increasing attention as promising alternatives. Neohesperidin (Neo), a major bioactive flavonoid derived from the TCM herbs such as <i>Citrus aurantium</i> and its related species, has been historically associated with heat-clearing and detoxifying properties in TCM theory. However, its role in mastitis remains unclear. Herein, we investigated the protective effects of Neo on BMB integrity using an LPS-induced mastitis model. Our results demonstrate that Neo significantly alleviates mammary tissue damage and preserves BMB function. Further mechanistic studies indicate that Neo attenuates LPS-induced inflammatory responses and oxidative stress in mammary epithelial cells by inhibiting the TLR4/NF-κB pathway and concurrently activating the AMPK/Nrf2/HO-1 axis. Additionally, 16S rRNA sequencing and fecal microbiota transplantation (FMT) experiments demonstrated that Neo alleviates mastitis by modulating the gut microbiota (increasing beneficial bacteria and reducing harmful bacteria). In summary, this study confirms that Neo can mitigate mastitis and protect BMB function through its anti-inflammatory, antioxidant, and microbiota-regulating effects. The research not only elucidates the molecular mechanisms by which Neo exerts its mammary protective effects through inflammation-oxidative stress-gut microbiota but also provides new insights for the prevention and treatment of mastitis.