Abstract
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.
Highlights
Lotus leaves (Nelumbo nucifera Gaertn.) are commonly dried and used for tea and traditional Chinese medicines [1]
Because of its multiple effects, lotus leaf has been applied in the development and production of healthy food and has been proved to contain carbohydrates, lipids, and proteins that are common in plants and various bioactive components, the most important of which are flavonoids and alkaloids [6]. e flavonoid extract of lotus leaf (FELL) possesses antioxidative, anti-inflammatory, and lipid regulatory properties through biologically active substances [7,8,9]
Regular intake of high-concentration alcohol will lead to thinning of the gastric mucosa, necrosis and detachment of epithelial cells, injury and embolism in the microvascular endothelium, and ischemic and anoxic necrosis in tissue, resulting in gastric mucosal erosion and ulcer formation, as well as gastroduodenal mucosal damage and related gastropathy [13]
Summary
Lotus leaves (Nelumbo nucifera Gaertn.) are commonly dried and used for tea and traditional Chinese medicines [1]. Lotus leaf tea is effective for weight loss and gastrointestinal protection, and traditional Chinese medicines made of lotus leaves have been used for weight loss, lipid reduction, antioxidation, anticonvulsion, and anti-liver fibrosis [2,3,4,5]. Alcohol causes neutrophil infiltration in the gastric mucosa, releases MPO, oxygen free radicals, active oxidation metabolites such as superoxide anion (O2 −), and protease, and adheres to the vascular endothelium, producing vascular occlusion and mucosal damage [14]. Oxygen free radicals on mitochondria act to reduce ATP production, leading to dysfunctional Na+K+-ATPase and elevated Na+ concentration in cells, triggering Na+-Ca2+ exchange, and increasing intracellular calcium. Active oxygen can directly inhibit Ca2+-Mg2+-ATPase, eventually leading to calcium overload
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