ABSTRACT
The purpose of this research is to identify the chemical constituents of sea buckthorn leaves extract (SBLE) and explore its hypoglycemic biological activity. SBLE was prepared by hot reflux extraction with 65% ethanol, and its chemical composition was analyzed by ultra-high-performance liquid chromatography-photodiode array-mass spectrometry/mass spectrometry (UHPLC-PDA-MS/MS) system. The animal experiments were compliant with ethical principles for animal use and had been approved by the Animal Experiment Ethics Committee of Jinan University. Mice were injected with streptozocin (STZ) to establish a hyperglycemic animal model, and SBLE (1.5 g·kg-1) was administered by gavage for 5 weeks. The fasting blood glucose (FBG) and oral glucose tolerance were detected. Normal mice were given SBLE (1.5 g·kg-1) by intragastric administration for 10 days, and blood was collected from the tail vein to detect the changes in blood glucose within 120 min after sucrose or starch loading. The mucous membrane of the small intestine of mice was taken to detect the activity of α-glucosidase (AG), and the activity of yeast-derived AG incubated with SBLE was evaluated. The glucose uptake by Caco-2 cells treated with SBLE was detected by fluorescence microscopy and cytometry, and the gene expression of sodium-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2) in Caco-2 cells were detected by real-time quantitative PCR (qPCR). A total of 18 compounds were identified, mainly including tannins and flavonoids. SBLE reduced FBG and increased oral glucose tolerance in STZ hyperglycemic mice. SBLE effectively inhibited the increase of blood glucose caused by starch intake in normal mice. SBLE exerted good inhibitory activity on yeast-derived AG (IC50 = 16.94 μg·mL-1) and small intestinal mucosa AG with an inhibition rate of 15.48%. SBLE (25-100 μg·mL-1) dose-dependently inhibited glucose uptake by Caco-2 cells, and SBLE significantly reduced the mRNA level of SGLT1 without changing the expression of GLUT2. In conclusion, the UHPLC characteristic fingerprint of SBLE is established with 18 chemical components identified by mass spectrometry, and SBLE exerts hypoglycemic effect by inhibiting the activity of AG and the absorption of glucose by intestinal epithelial cells.
ABSTRACT
This study aimed to assess the hypoglycemic activity, and in vitro inhibition of α-glucosidase, inhibition of the advanced glycation end products (AGEs), and total antioxidant capacity were used to clarify its bioactivity. Furthermore, the potential hypoglycemic active chemical constituents in the aqueous extract of Osmanthus fragrans var. thunbergii flower were characterized using high performance liquid chromatography-electrospray ionization-quadruple time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS) method. The result showed that in vitro inhibition of α-glucosidase of the extract (IC50 = 2.11 ± 0.26 mg·mL-1) were similar to acarbose (IC50 = 2.88 ± 0.32 mg·mL-1), and it inhibited the AGEs formation and the total antioxidant capacity in a certain extent. Based on the MS fragmentation pathway analysis of reference chemical acteoside contained in this extract, and related references, 73 constituents were tentatively identified from the aqueous extract of Osmanthus fragrans var. thunbergii flower, including 58 phenylethanoids, 8 caffeoylquinic acids, 1 flavonoid vicenin-2, and 6 common organic chemicals in plant. Furthermore, 8 unknown alkaloids were characterized in this work. Among of these chemicals, 61 phenylethanoids were supposed to be detected for the first time. In conclusion, this work disclosed the potential hypoglycemic active constituents of Osmanthus fragrans var. thunbergii flower.
ABSTRACT
Seven compounds were isolated from the alcohol extract of Edgeworthia gardneri by various technologies, including silica gel, Sephadex LH-20 and high performance liquid chromatography, and were identified as edgeworthiaside A (1), 2,4,6-trichlorol-3-methyl-5-methoxy-phenol 1-O-β-D-glucopyranosyl-(1-6)-β-D-glucopyranoside (2), 2,6-dimethoxy-4-(2-propen-1-yl)phenyl 6-O-(6-deoxy-α-L-mannopyranosyl)-β-D-glucopyranoside (3), eugenol rutinoside (4), tiliroside (5), edgeworoside C (6), and salicylic acid (7). Compound 1 is a new chlorophenyl glycoside and 2-4 were isolated for the first time from Edgeworthia gardneri. The in vitro inhibition of α-glucosidase showed that the inhibition rate of compounds 1 and 2 were similar to acarbose.
ABSTRACT
italic>α-Glucosidase inhibitors play an important role in the treatment of diabetes. This study established a high-resolution bioassay profiling platform for rapidly screening α-glucosidase inhibitors in natural product extracts. Five α-glucosidase inhibitors were identified from Malus hupehensis, namely, 3-hydroxyphloridzin, quercetin-3-O-β-D-glucopyranoside, phloridzin, avicularin and quercitrin. The establishment and successful application of this platform provides a powerful tool for the efficient discovery of anti-diabetic active ingredients in complex systems.
ABSTRACT
Sangzhi alkaloids (SZ-A) are derived from traditional Chinese medicine Ramulus Mori, serving well as an innovative antidiabetic drug, due to α-glucosidase inhibition. To evaluate the potency of glucosidase inhibitory effect of SZ-A, the enzyme-based screening platforms, including sucrase, maltase and amylase were established, and IC50 was calculated. The effects of SZ-A on postprandial blood glucose at a single dose, oral sucrose, starch and glucose loading were determined in normal ICR mice and alloxan-induced hyperglycemic mice. To confirm the anti-diabetic effects of SZ-A on glucose and lipid metabolism after long-term administration, the postprandial and fasting blood glucose, serum insulin, urinary glucose levels, glycosylated serum proteins and blood lipid levels were determined in high-fat fed C57 obese mice (pre-diabetic HFC57 mice) and diabetic rats induced by streptozotocin (STZ). The Experimental Animal Welfare Ethics Committee of the Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College approved all of the protocols for this research. We found that SZ-A exhibited a significant inhibitory effect on the sucrase and maltase. SZ-A showed no effect on amylase. In normal ICR mice and alloxan-induced hyperglycemic mice, SZ-A at a single dose significantly delayed and reduced the peak of blood glucose after sucrose or starch loading, but showed no effect on the increase of blood glucose after glucose loading. In STZ diabetic rats, SZ-A significantly reduced the postprandial or fasting blood glucose levels, glycosylated serum proteins and urinary glucose. SZ-A also reduced serum triglyceride (TG) and cholesterol (TC) levels after 3 weeks of treatment. SZ-A ameliorated the postprandial blood glucose or the fasting blood glucose elevation, and reduced the incidence of hyperglycemia in HFC57 mice. SZ-A decreased the basal insulin level, improved insulin sensitivity, and ameliorated glucose intolerance in pre-diabetic HFC57 mice. Our results indicated that SZ-A had a novel inhibitory activity on α-glucosidase, especially on disaccharidases. SZ-A at a single dose significantly reduced the peak of blood glucose elevation and delayed the increase of blood glucose in normal and diabetic mice after disaccharide and polysaccharide loading. Long-term SZ-A treatment improved glucose and lipid metabolic profiles by delaying carbohydrate absorption from the intestine and reduced the postprandial blood glucose levels in both pre-diabetic and diabetic animal models. Therefore, SZ-A application may display a beneficial role in preventing the development and complications of diabetes.