Inhibitory Effect of Flavonoid Extract of Lotus Leaf on Alcohol-Induced Gastric Injury by Antioxidant Capacity in Mice

The aim of this study was to investigate the antioxidant effects of flavonoid extract of lotus leaf (FELL) in vitro and in mice with gastric injury and elucidate the inhibitory effect of FELL on alcohol-induced gastric injury by antioxidant capacity. Gastric juice volume and acid value were measured in the established alcohol-induced acute gastric injury model in mice. Hematoxylin and eosin staining demonstrated the morphological changes in the gastric mucosa. FELL improved the alcohol-induced gastric lesions. Serological testing results showed that FELL significantly increased the levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and nitric oxide (NO) and significantly reduced the levels of MDA and MPO in mice with gastric injury. Besides, FELL significantly reduced the levels of interleukin 6 (IL-6), interleukin 12 (IL-12), tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ). The quantitative polymerase chain reaction (qPCR) and Western blot results proved that FELL upregulated the mRNA and protein expressions of SOD1, SOD2, CAT, epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR), neuronal nitric oxide synthase (nNOS), and endothelial nitric oxide synthase (eNOS) and downregulated the expression of inducible nitric oxide synthase (iNOS) in the gastric tissue of mice with gastric injury. Five compounds, including kaempferitrin, hyperoside, astragalin, phloridzin, and quercetin, were detected in FELL using high-performance liquid chromatography. Thus, FELL has an inhibitory effect on experimental alcohol-induced gastric injury because of the antioxidant capacity of the five compounds. Its effect increases as the FELL concentration increases, which is close to that of ranitidine. FELL, which is an active substance, provides a good gastroprotective effect