Low-Dose, Post-Storage Dancong Tea Attenuates Hydroalcohol-Induced Gastric Damage via Modulation Antioxidant and Anti-Inflammatory Pathways

Dancong tea is a representative type of oolong tea typically stored for over six months before sale to reduce gastrointestinal irritation. The effects and mechanisms of this storage on gastrointestinal damage remain unclear. Therefore, this study investigated hydrochloric acid and ethanol (HCl/EtOH)-induced gastric injury in mice. The results indicate that six-month-stored Dancong tea (OldT) alleviated gastric injury at low doses but showed no protective effect at high doses; in fact, high-dose OldT exacerbated injury. In contrast, fresh tea (NewT) aggravated gastric injury at both low and high doses. Hematoxylin and eosin (H&E) staining revealed that low-dose OldT significantly attenuated gastric histopathological injury. Mechanistically, low-dose OldT reduced injury via antioxidant and anti-inflammatory pathways (Nrf-2/HO-1 activation and NF-κB inhibition), and inhibiting lipid peroxidation, reactive oxygen species (ROS), nitric oxide (NO), and inflammatory mediators (iNOS, COX-2, IL-6, TNF-α). These findings suggest that storage reduces the gastrointestinal irritant properties of fresh Dancong tea, providing a scientific basis for industrial practice and guiding consumption.