Intervention effects of lotus leaf flavonoids on gastric mucosal lesions in mice infected with Helicobacter pylori

Abstract

Helicobacter pylori (H. pylori) is one of the main factors that cause gastric lesions. The lotus leaf is an edible plant used in traditional Eastern medicine. This study evaluates the intervention effects of lotus leaf flavonoids (LLF) on gastric mucosal lesions in mice infected with H. pylori and explores their mechanism of action. High-performance liquid chromatography analysis reveals that LLF contain kaempferitrin (kaempferol-3,7-dirhamnoside), hypericin, astragalin (kaempferol-3-glucoside), phlorizin, and quercetin. LLF can reduce the number of gastric mucosal lesions and tissue lesions in mice with H. pylori-induced gastric lesions. LLF can increase the levels of somatostatin and vasoactive intestinal peptide in the serum of mice with gastric lesions and decrease the levels of substance P and endothelin-1 to inhibit gastric lesions. LLF can also reduce the levels of interleukin (IL)-6, IL-12, tumor necrosis factor (TNF)-α, and interferon-gamma cytokines in the serum of mice with gastric lesions. Using a quantitative polymerase chain reaction assay it can be seen that LLF can downregulate mRNA expressions of TNF-α, IL-1β, myeloperoxidase, keratin (KRT) 16, KRT6b, and transglutaminase 3 epidermal in the gastric tissues of mice with gastric lesions. Western blot analysis indicates that LLF can downregulate the protein expressions of caspase-1, Nod-like receptor protein 3, IL-1β, TNF-α, and Toll-like receptor 4 in the gastric tissues of mice with gastric lesions. LLF have beneficial effects on gastric lesions induced by H. pylori. Meanwhile LLF is more active in competition with ranitidine. LLF represent an active substance that can inhibit H. pylori-induced gastric lesions. The flavones of LLF may enhance the inhibition of gastric mucosal lesions by promoting the interaction between the compounds.

Fig. 1. Flavonoid constituents of lotus leaf. (A) Standard chromatograms; (B) lotus leaf flavonoids chromatograms. (1) kaempferitrin; (2) hypericin; (3) astragalin; (4) phlorizin; (5) quercetin.

Fig. 2. Observation of gastric mucosal lesions in mice with Helicobacter pylori. Ranitidine group: 100 mg per kg b.w. ranitidine treatment dose; FLL-L group: 50 mg per kg b.w. lotus leaf flavonoids dose; FLL-H group: 100 mg per kg b.w. lotus leaf flavonoids dose.

Fig. 3. Pathological observation of gastric mucosal lesions in mice with Helicobacter pylori. Ranitidine group: 100 mg per kg b.w. ranitidine treatment dose; FLL-L group: 50 mg per kg b.w. lotus leaf flavonoids dose; FLL-H group: 100 mg per kg b.w. lotus leaf flavonoids dose.

Fig. 4. mRNA expression of TNF-α, IL-1β and MPO in gastric tissue of mice. Values presented are the mean ± standard deviation. ^a–eMean values with different letters in the bars are significantly different (p < 0.05) according to Duncan's multiple-range test. Ranitidine group: 100 mg per kg b.w. ranitidine treatment dose; FLL-L group: 50 mg per kg b.w. lotus leaf flavonoids dose; FLL-H group: 100 mg per kg b.w. lotus leaf flavonoids dose.

Fig. 5. mRNA expression of KRT16, KRT6b and TGM3 in gastric tissue of mice. Values presented are the mean ± standard deviation. ^a–eMean values with different letters in the bars are significantly different (p < 0.05) according to Duncan's multiple-range test. Ranitidine group: 100 mg per kg b.w. ranitidine treatment dose; FLL-L group: 50 mg per kg b.w. lotus leaf flavonoids dose; FLL-H group: 100 mg per kg b.w. lotus leaf flavonoids dose.

Fig. 6. Protein expression of Caspase-1, NLRP3, IL-1β, TNF-α and TLR4 in gastric tissue of mice. Values presented are the mean ± standard deviation. ^a–eMean values with different letters in the bars are significantly different (p < 0.05) according to Duncan's multiple-range test. Ranitidine group: 100 mg per kg b.w. ranitidine treatment dose; FLL-L group: 50 mg per kg b.w. lotus leaf flavonoids dose; FLL-H group: 100 mg per kg b.w. lotus leaf flavonoids dose.