Polyphenols in Kuding tea help prevent HCl/ethanol-induced gastric injury in mice
We conducted the present study to determine the gastric injury preventive effects of polyphenols in Kuding tea (KTPs) in Kunming (KM) mice through the inhibition of gastric-acid secretion and the protection of the gastric mucosa. Mice treated with a high concentration of Kuding tea polyphenols (HKTP) had lower serum levels of interleukin-6 (IL-6), IL-12, tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), motilin (MOT), substance P (SP), and endothelin-1 (ET-1), and higher serum levels of somatostatin (SS) and vasoactive intestinal peptide (VIP) than did the mice in the control group. Serum and gastric tissue levels of nitrous oxide (NO), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and GSH were higher in the HKTP-treated mice than in the control mice, but malondialdehyde (MDA) levels were lower in the HKTP-treated mice than in the control mice. The expression of occludin, epidermal growth factor (EGF), EGF receptor (EGFR), vascular endothelial growth factor (VEGF), nuclear factor of κ-light polypeptide gene enhancer in B-cells inhibitor-α (IκBα), Cu/Zn-SOD (cuprozinc-superoxide dismutase), Mn-SOD (manganese-superoxide dismutase), GSH-Px (glutathione peroxidase), neuronal nitric oxide synthase (nNOS), endothelial NOS (eNOS), messenger RNA (mRNA) and protein in gastric tissue was stronger in the HKTP-treated mice than in the control mice, while the expression of p38 mitogen-activated protein kinase (P38MAPK, or p38), nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB), inducible NOS (iNOS), and cyclooxygenase-2 (COX-2) was weaker in the HKTP group than in the control group. And HKTP also could reduce the TNF-α, IL-1β (interleukin-1 beta), and IL-6 mRNA expression in gastric injury mice. A high performance liquid chromatography (HPLC) assay showed that Kuding tea polyphenols (KTPs) contained chlorogenic acid, cryptochlorogenic acid, and isochlorogenic acids A, B, and C. These constituents contributed to the preventive effects of KTPs on gastric injury. According to these results, KTPs are a kind of active component that have a strong preventive effect on gastric injury.