Preclinical Evaluation of the Antidiabetic Effect and Phytochemical HPLC-MS ESI-QTOF Analysis of Sclerocarya birrea (A. Rich) Hoscht Bark of Trunk Aqueous Extract in Alloxan-Induced Diabetic Wistar Rat

Introduction: Diabetes is a serious public health problem requiring complex treatment. Numerous ethnopharmacological studies have reported the traditional use of Sclerocarya birrea in managing diabetic patients. This study aims to demonstrate, preclinically, the antidiabetic effects of the aqueous decoction of S. birrea trunk bark. Methods: Phytochemical analysis was performed by HPLC-MS. The effects of the extracts (Sb5 and Sb25) and 0.9% NaCl on the normal blood glucose levels of the animals were determined. Diabetes induction was performed intraperitoneally by administering a single dose of alloxan (150 mg/kg) in normoglycemic rats. The antidiabetic effects of the extracts (Allox + Sb5, Allox + Sb25) and glibenclamide (Allox + Glib5) were determined in Alloxan-induced diabetic animals for four weeks. Results: Interpretation of mass spectra obtained by HPLC-MS allowed the tentative identification of vanillic acid-4-sulfate and rhamnetin in Sb extract. Investigated doses of Sb extract showed an antidiabetic impact similar to the reference, glibenclamide, with a return to normal blood glucose in all treated rats only after 4 days of treatment. Furthermore, Sb extract treatments reduced weight loss in diabetic rats. Sb had no negative impact on the balance of total cholesterol, triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL). Conclusion: The present study demonstrated the antidiabetic efficacy and, to some extent, the beneficial effects of Sb extract on Alloxan-induced diabetic rats’ health. Detection of antidiabetic phytochemicals such as vanillic acid-4-sulfate and rhamnetin would justify this pharmacological property of the aqueous decoction of S. birrea trunk bark.

Triterpenoids from Uncaria rhynchophylla and Their PTP1B Inhibitory Activity

Uncaria rhynchophylla(Gouteng)is a famous traditional Chinese medicine used for psychiatric and hypotensive purposes in China.In this study,the ethyl acetate(EtOAc)part of U.rhynchophylla was revealed with protein tyrosine phosphatase 1B(PTP1B)inhibitory activity.Subsequent investigation on the EtOAc part yielded one new triterpenoid,3β-formyloxy-6β,19α-dihydroxyurs-12-en-28-oic acid(1)and four known ones,3β,6β,19α-trihydroxyurs-12-en-28-oic acid(2),2-oxopomolic acid(3),3β,19α-dihydroxy-6-oxo-olean-12-en-28-oic acid(4)and sumaresinolic acid(5).The structure of compound 1 was determined by extensive HRESIMS,IR,1D and 2D NMR spectroscopic analyses.Two ursane-type triterpenoids(2 and 3)showed selective inhibition on PTP1B with IC50 values of 48.2 and 178.7μM.The enzyme kinetic study suggested that compounds 2 and 3 were mixtype inhibitors on PTP1B with Ki values of 15.6 and 132.5μM.This investigation manifests the antidiabetic potency of U.rhynchophylla with triterpenoids as the active constituents.

Hypoglycemic and Hypolipidemic Effects of Lycium barbarum Polysaccharide in Diabetic Rats

Objective To study the antidiabetic effects and the underlying molecular mechanisms of Lycium barbarum polysaccharide（LBP） and its DEAE cellulose elution fraction LBP-IV in diabetic rats induced by high fat diet（HFD） and streptozotocin（STZ）. Methods After ig administration of LBP-IV [50, 100, and 200 mg/（kg·d）] and LBP [100 mg/（kg·d）] once daily for consecutive 4 weeks to diabetic rats, the glucose and lipids in blood, m RNA expression of phosphoenolpyruvate carboxykinase（PEPCK）, sterol regulatory element binding-protein-1c（SREBP-1c）, and fatty acid synthase（FAS） in liver were determined. Results Ig administration of LBP and LBP-IV significantly decreased the levels of blood glucose, Hb A1 c, TC, TG, and LDL-C, as well as the hepatic m RNA expression of PEPCK, SREBP-1c, and FAS, whereas significantly increased the oral glucose tolerance of diabetic rats. Conclusion The findings suggest that the antidiabetic effects of LBP and LBP-IV are associated with the decreased hepatic m RNA expression of PEPCK, SREBP-1c, and FAS in HFD-STZ induced diabetic rats.