ABSTRACT
ETHNOPHARMACOLOGICAL RELEVANCE: Diabetic kidney damage (DKD) is one of the most common complications of diabetes, which is known as a chronic inflammatory kidney disease caused by persistent hyperglycemia. White tea was originally used as a folk medicine to treat measles in ancient China. What arouses our interest is that there is a traditional method to treat diabetes with white tea taken from over 30-year-old tree of Camellia sinensis L. However, there are few reports on the renal protection of white tea. AIM OF THE STUDY: This present study was designed to study the potential protective effects of white tea (WT) and old tree white tea (OTWT) on high-fat-diet (HFD) combined with streptozotocin (STZ)-induced type 2 diabetic mice to explore the possible mechanism of WT/OTWT against DKD. MATERIALS AND METHODS: C57BL/6 mice were randomly divided into four groups: NC, T2D, WT (400 mg/kg·b.w, p.o.), OTWT (400 mg/kg·b.w, p.o.). Diabetes was established in all groups except NC group, by six weeks of HFD feeding combined with STZ (50 mg/kg, i.p.) for 3 times, treatments were administered for six weeks and then all the animals were decapitated; kidney tissues and blood samples were collected for the further analysis, including: levels of insulin, lipid metabolism (TG, TC, HDL, LDL, FFA), antioxidative enzymes (catalase (CAT), super oxide dismutase (SOD), glutathione peroxidase (GPx)), blood urea nitrogen (BUN) and creatine, inflammatory cytokines (TNF-α, IL-1ß, COX-2, iNOS, MCP-1), advanced glycation end products (AGE), receptor of AGE (RAGE), Nrf2, AMPK, SIRT1, and PGC-1α. H&E, PAS and Masson staining were performed to examine the histopathological alterations of the kidneys. RESULTS: Our data showed that WT and OTWT reversed the abnormal serum lipids (TG, TC, HDL, LDL, FFA) in T2D mice, upregulated antioxidative enzymes levels (CAT, SOD, GPx) and inhibit the excessive production of proinflammatory mediators (including MCP-1, TNF-α, IL1ß, COX-2 and iNOS) by varying degrees, and OTWT was more effective. In histopathology, OTWT could significantly alleviate the accumulation of renal AGE in T2D mice, thereby improving the structural changes of the kidneys, such as glomerular hypertrophy, glomerular basement membrane thickening and kidney FIbrosis. CONCLUSIONS: Both WT and OTWT could alleviate the diabetic changes in T2D mice via hypoglycemic, hypolipidemic, anti-oxidative and anti-inflammatory effects, while OTWT was more evident. OTWT could prominently alleviate the accumulation of AGE in the kidneys of T2D mice, thereby ameliorating the renal oxidative stress and inflammatory damage, which was associated with the activation of SIRT1/AMPK pathway.
Subject(s)
AMP-Activated Protein Kinases/metabolism , Camellia sinensis/chemistry , Diabetes Mellitus, Experimental/therapy , Diabetic Nephropathies/therapy , Protective Agents/therapeutic use , Sirtuin 1/metabolism , Tea/chemistry , Animals , Blood Glucose/drug effects , Diabetic Nephropathies/pathology , Glomerular Basement Membrane/drug effects , Glycation End Products, Advanced/drug effects , Insulin/blood , Insulin Resistance , Lipids/blood , Male , Mice, Inbred C57BL , NF-E2-Related Factor 2/metabolism , NF-kappa B/metabolism , Oxidoreductases/blood , Protective Agents/pharmacology , Signal Transduction/drug effectsABSTRACT
BACKGROUND: White tea, considered to be the oldest form of tea, is becoming a popular beverage for its organoleptic characteristics. Peppermint tea, used as a herbal remedy for centuries, is now also very popular throughout the world as herbal tea. What interested us was that in ancient China, peppermint was used in combination with tea as a detoxification or anti-inflammatory agent. However, there are few reports on the combined use of white tea and peppermint. Therefore, this study aims to investigate the antibacterial and anti-inflammatory activities of white tea in combination with peppermint. RESULTS: A synergistic inhibitory effect against four bacterial strains, especially against Staphylococcus argenteus, was observed in the combination of white tea and peppermint in vitro. In addition, the combined formula demonstrated a stronger anti-inflammatory effect in vivo than either of the two used alone, which was associated with the decrease of the pro-inflammatory cytokines of interleukin-6 (IL-6), interleukin-1beta (IL-1ß), tumor necrosis factor-alpha (TNF-α), cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). In a further mechanism study, it was found that white tea and peppermint inhibited the phosphorylation of p-IκB-α and mitogen-activated protein kinase (MAPK) at different degrees. While the enhanced anti-inflammatory effect of the combined formula was associated with the combination of NF-κB down-regulation and p-MAPK inhibition. CONCLUSION: In our study, it was for the first time shown that when white tea was combined with peppermint, the antibacterial and anti-inflammatory effects were enhanced. The results suggested an effective application of white tea in combination with peppermint as a potential antibacterial and anti-inflammatory functional food. © 2020 Society of Chemical Industry.
Subject(s)
Anti-Bacterial Agents/administration & dosage , Anti-Inflammatory Agents/administration & dosage , Camellia sinensis/chemistry , Edema/drug therapy , Mentha piperita/chemistry , Plant Extracts/administration & dosage , Animals , Cyclooxygenase 2/genetics , Cyclooxygenase 2/immunology , Drug Synergism , Edema/genetics , Edema/immunology , Humans , Interleukin-6/genetics , Interleukin-6/immunology , Male , Mice , NF-kappa B/genetics , NF-kappa B/immunology , Nitric Oxide Synthase Type II/genetics , Nitric Oxide Synthase Type II/immunology , Plant Leaves/chemistry , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/growth & development , Staphylococcus/drug effects , Staphylococcus/growth & development , Tumor Necrosis Factor-alpha/genetics , Tumor Necrosis Factor-alpha/immunologyABSTRACT
The use of plant-based beverages to interfere with the onset of diabetes may be a promising approach towards type 2 diabetes mellitus (T2DM). The present study investigated the antidiabetic effects of the oral consumption of white tea and G. pentaphyllum (Jiaogulan), especially their combination on HFD/STZ-induced T2DM in C57BL/6 mice. White tea and Jiaogulan administration could mitigate glycolipid metabolic disorders in the diabetic mice by different degrees. White tea administration markedly reduced the blood glucose and ameliorated the glucose intolerance compared to the T2DM mice. Moreover, white tea consumption could protect the islet ß-cells against oxidative and inflammatory damage, related to the Nrf-2 signaling pathway. Jiaogulan prominently attenuated liver lipid accumulation by downregulation of SREBP levels. However, interestingly, when white tea was used in combination with Jiaogulan, these effects were enhanced to a certain extent. In particular, the combination significantly suppressed the hepatic G6Pase expressions by activating the AMPK pathway, thus inhibiting gluconeogenesis and improving insulin resistance. On the other hand, the combined formula could regulate the PPAR expressions and ameliorate the hepatic inflammation, further activating the IRS/PI3K/AKT pathway and exerting the antidiabetic potential. Therefore, it was speculated that the antidiabetic effect of this combination may be associated with the AMPK/PI3K pathways. Our findings might provide insight into the combined use of white tea with Jiaogulan tea as a potential functional beverage or food for preventing T2DM.
