Acute Anti-Hyperglycaemic Activity of Five Traditional Medicinal Plants in High Fat Diet Induced Obese Rats.

BACKGROUND: Diabetes mellitus (DM), a prevalent non-communicable disease, is a metabolic condition involving defective pancreatic ß-cells and/or insulin resistance. Researchers are presently exploring traditional medicinal plants to identify alternatives for treating diabetes due to the various disadvantage of current anti-diabetic medicines. OBJECTIVE: The present study evaluated the anti-hyperglycaemic effects of ethanol extracts of five medicinal plants (EEMPs) (Gynura nepalensis, Glochidion thomsonii, Clerodendrum splendens, Clerodendrum infortunatum and Xanthium strumarium) which are traditionally used as an ethnomedicine to treat diabetes and numerous other health problems. METHODS: High-fat fed (HFF) obese rats were used to perform acute in vivo tests, including oral glucose tolerance, feeding test, metabolic studies, and gastrointestinal motility using BaSO4 milk solution. Priliminary phytochemical screening were performed to discover the presence or absence of alkaloids, tannins, saponins, steroids, glycosides, flavonoids, and reducing sugars in extracts. RESULTS: Oral administration of ethanol extracts (250 mg/kg, body weight), along with glucose (18 mmoL/kg body weight), ameliorated glucose tolerance (p < 0.05-0.01). In addition, the extracts improved gut motility (250 mg/kg; p < 0.05-0.001), as well as reduced food intake during the feeding test (250 mg/kg; p < 0.05-0.001). Phytochemical screening of these medicinal plants depicted the presence of flavonoids, alkaloids, tannins, saponins, steroids and reducing sugars. CONCLUSIONS: Phytochemicals such as flavonoids, tannins and saponins may be responsible for the glucose-lowering properties for these plants. Additional research is warranted to fully identify the bioactive phytomolecules and mechanistic pathways that might lead to the development of a viable, cost-effective type 2 diabetes therapy.

Antidiabetic Actions of Ethanol Extract of Camellia sinensis Leaf Ameliorates Insulin Secretion, Inhibits the DPP-IV Enzyme, Improves Glucose Tolerance, and Increases Active GLP-1 (7-36) Levels in High-Fat-Diet-Fed Rats.

Camellia sinensis (green tea) is used in traditional medicine to treat a wide range of ailments. In the present study, the insulin-releasing and glucose-lowering effects of the ethanol extract of Camellia sinensis (EECS), along with molecular mechanism/s of action, were investigated in vitro and in vivo. The insulin secretion was measured using clonal pancreatic BRIN BD11 ß cells, and mouse islets. In vitro models examined the additional glucose-lowering properties of EECS, and 3T3L1 adipocytes were used to assess glucose uptake and insulin action. Non-toxic doses of EECS increased insulin secretion in a concentration-dependent manner, and this regulatory effect was similar to that of glucagon-like peptide 1 (GLP-1). The insulin release was further enhanced when combined with isobutylmethylxanthine (IBMX), tolbutamide or 30 mM KCl, but was decreased in the presence of verapamil, diazoxide and Ca2+ chelation. EECS also depolarized the ß-cell membrane and elevated intracellular Ca2+, suggesting the involvement of a KATP-dependent pathway. Furthermore, EECS increased glucose uptake and insulin action in 3T3-L1 cells and inhibited dipeptidyl peptidase IV (DPP-IV) enzyme activity, starch digestion and protein glycation in vitro. Oral administration of EECS improved glucose tolerance and plasma insulin as well as inhibited plasma DPP-IV and increased active GLP-1 (7-36) levels in high-fat-diet-fed rats. Flavonoids and other phytochemicals present in EECS could be responsible for these effects. Further research on the mechanism of action of EECS compounds could lead to the development of cost-effective treatments for type 2 diabetes.