Desheng Xu

MDG-1, a polysaccharide from Ophiopogon japonicus exerts hypoglycemic effects through the PI3K/Akt pathway in a diabetic KKAy mouse model

ETHNOPHARMACOLOGICAL RELEVANCE Ophiopogon japonicus is a traditional Chinese medicine that might be helpful for the treatment of type 2 diabetes. Recent studies have confirmed its beneficial properties, but not the mechanism of action. AIM OF STUDY In this study, we examined the effects of a water-soluble β-d-fructan (MDG-1) from O. japonicus on type 2 diabetes through the PI3K/Akt pathway in a diabetic KKAy mouse model. MATERIALS AND METHODS MDG-1 was extracted from the tube root of O. japonicus and purified as described previously (Xu et al., 2005). The KKAy mice were gavaged once daily with either distilled water, MDG-1or rosiglitazonefor 8 weeks. Blood glucose levels were tested regularly for the fed and fasted mice. In order to evaluate the effect of MDG-1 on disease progression, the proteins of InsR/IRS-1/PI3K/Akt/GSK-3/Glut-4 were detected by Western blotting and serum TG, TC, HDL-C, LDL-C were also dertermined. RESULTS MDG-1 reduced the hyperglycemia, hyperinsulinemia and hyperlipidemia in the KKAy mice. The oral glucose tolerance test (OGTT) and the level of insulin in the serun showed that insulin resistance in KKAy mice was ameliorated after MDG-1 treated. After 8 weeks treatment with 300mg/kg MDG-1, the content of triglycerides (TG) and low density lipoprotein cholesterol (LDL-C) the serum decreased significantly. Meanwhile high density lipoprotein cholesterol (HDL-C) content increased notably. MDG-1 did not have any effect on total cholesterol (TC) content in the serum, whereas rosiglitazone significantly decreased the TC content. In addition, MDG-1 upregulates the phosphoinositide 3-kinase p85 subunit, Akt, insulin receptor (InsR), insulin receptor substrate-1 (IRS-1) and Glut-4 expression, but downregulates glycogen synthase kinase 3β expression. CONCLUSIONS These data indicate that MDG-1 has remarkable anti-diabetic activity through the InsR/IRS-1/PI3K/Akt/GSK-3/Glut-4 signaling pathway. We believe that MDG-1 is a promising anti-diabetic compound that will be helpful for the treatment of T2DM.

Effect and mechanism of senkyunolide I as an anti-migraine compound from Ligusticum chuanxiong

Objective  To evaluate the analgesic and anti‐migraine activities of senkyunolide I from Ligusticum chuanxiong.

Hypoglycemic effects of MDG-1, a polysaccharide derived from Ophiopogon japonicas, in the ob/ob mouse model of type 2 diabetes mellitus

Ophiopogon japonicus is a traditional Chinese medicine used to treat diabetes mellitus. We investigate the anti-ischemic properties of a water-soluble β-D-fructan (MDG-1) from O. japonicus, and assess the antidiabetic effects of MDG-1. In the study, ob/ob mice were treated with 150 mg/kg or 300 mg/kg MDG-1 by gavage for 23 d. Blood glucose levels were measured regularly. An oral glucose tolerance test (OGTT) was preformed on day 21. The levels of insulin, total cholesterol and triglyceride in the serum were measured at the end of administration. The liver triglyceride content and tissue weights were also determined. Results show that MDG-1 (300 mg/kg) was demonstrated to exert acute and long-term hypoglycemic effects on fed blood glucose in ob/ob mice. However, only a marginal hypoglycemic effect on fasting blood glucose levels was observed. MDG-1 (300 mg/kg) improved oral glucose tolerance and reduced serum insulin levels and triglyceride content in the liver in ob/ob mice. Furthermore, a reduction in body weight gain and the weight of subcutaneous fat were observed following treatment with MDG-1 (150 mg/kg) compared with the control group. MDG-1 had no significant effects on the total cholesterol and triglyceride levels, food intake and other adipose and organ tissues. These data suggest that MDG-1 exhibits hypoglycemic activity and reduces insulin resistance.

A polysaccharide, MDG-1, induces S1P1 and bFGF expression and augments survival and angiogenesis in the ischemic heart.

Ophiopogon japonicus is a traditional Chinese medicine used to treat cardiovascular disease. Recent studies have confirmed its beneficial properties, but not the mechanism of action. Herein, we investigate the anti-ischemic properties of a water-soluble beta-d-fructan (MDG-1) from Ophiopogon japonicus, and assess the cytoprotective and proangiogenic effects of MDG-1. MDG-1 protects cardiomyocyte and microvascular endothelial cells (HMEC-1) against oxygen glucose deprivation (OGD)-induced cell death, as well as protect myocardial cells from ischemia-induced death occurring after coronary artery ligation in rats. Meanwhile, MDG-1 stimulates the differentiation of HMEC-1 cells into capillary-like structures in vitro and functions as a chemoattractant in migration assays, and promotes neovascularization in ischemic myocardium. In addition, MDG-1 upregulates sphingosine kinase 1 and sphingosine-1-phosphate (S1P) receptor 1 expression. Both MDG-1 and S1P induce basic fibroblast growth factor (bFGF) expression in HMEC-1 cells. Further study revealed that both MDG-1 and S1P induce Akt and ERK phosphorylation in a dose- and time-dependent manner, an effect that is attenuated by pre-treatment with either the Akt inhibitor wortmannin or the ERK inhibitor PD98059, and MDG-1 can also induce eNOS phosphorylation and increases in production of NO. These data indicate that MDG-1 presented remarkable anti-ischemic activity and protects cardiomyocyte and HMEC-1 cells from ischemia-induced cell damage by inducing S1P1 and bFGF cytoprotective and proangiogenic effects via the S1P/bFGF/Akt/ERK/eNOS signaling pathway.

Poly(ethylene glycol)-Radix Ophiopogonis polysaccharide conjugates: Preparation, characterization, pharmacokinetics and in vitro bioactivity

Radix Ophiopogonis polysaccharide (ROP), a natural graminan-type fructan with Mw of ∼5kDa, had been found to have an excellent anti-myocardial ischemic activity. However, its rapid renal excretion following administration remarkably limits its efficacy and clinical use, which makes necessary the development of an effective delivery system. In this article, the feasibility of PEGylation to solve this problem was examined. A moderate coupling reaction between the hydroxyl-activated ROP and the amino-terminated mPEG was chosen to PEGylate ROP. Five different mPEG-ROP conjugates (with mPEG of molecular mass 2, 5 or 20kDa) were prepared, purified, characterized and evaluated in pharmacokinetics and in vitro bioactivity. Results showed that only when the apparent molecular weight of the conjugate approached to a certain value, would its plasma elimination reduce abruptly. In general, the conjugation caused the reduction in the bioactivity of ROP; however, well-preserved bioactivity was observed when the grafting degree of the conjugate was lower. Among the five conjugates studied, the one with an average 1.3 mPEG (20kDa) residues per single ROP was found to be satisfactory both in plasma retention and in bioactivity. It had a 47.4-fold increased elimination half-life and preserved approximately 74% of the bioactivity of ROP; moreover, the decrease in bioactivity is not significant. These findings demonstrate that PEGylation would be a promising approach for improving the clinical efficacy of ROP by prolonged retention in plasma.

Influence of sulfation on anti-myocardial ischemic activity of Ophiopogon japonicus polysaccharide

Ophiopogon japonicus polysaccharide (FOJ-5) from Radix ophiopogonis has shown anti-myocardial ischemic action in vitro and in vivo in our previous studies. In order to clarify the influence of chemical modifications on the action, a series of sulfated FOJ-5 (FOJ-5-S) with different substitution degrees were prepared and the anti-myocardial ischemic action of the natural FOJ-5 and the FOJ-5-S were studied in vitro and in vivo. Langendorff isolated rat hearts and acute myocardial ischemic rats induced by isoprenaline were employed as myocardial ischemic models in our experiments. The amplitude and frequency of cardiac contraction, coronary blood flow at different time points after ischemia/reperfusion were measured in vitro. The ST segment shift in electrocardiogram and lactate dehydrogenase level in blood plasma were observed on the in vivo model. The results indicated that FOJ-5 and FOJ-5-S had the anti-myocardial ischemic action compared with non-treated vehicle groups. Furthermore, it was found that FOJ-5-S had significant action on the in vivo model compared with FOJ-5 (P < 0.05). And the obtained results from the further study also indicated that only when the degree of substitution was in a certain range, the FOJ-5-S had excellent anti-myocardial ischemic activity.

A sensitive and specific HPGPC-FD method for the study of pharmacokinetics and tissue distribution of Radix Ophiopogonis polysaccharide in rats

Interest in antimyocardial ischemic activity of a graminan-type fructan with a weight average molecular weight of 4.8 kDa extracted from Radix Ophiopogonis (ROP) has necessitated the study of its pharmacokinetics and tissue distribution. For that, a simple HPGPC-FD method was developed for the sensitive and specific determination of FITC-ROP (fluorescein-isothiocyanate-labeled ROP) in plasma and rat tissues (heart, liver, spleen, lung, kidney, brain and stomach). The analyte was separated on a Shodex Sugar KS-802 high-performance gel column with 0.1 M phosphate buffer (pH 7.0) as mobile phase at a flow rate of 0.5 mL/min, and fluorescence detection at lambda(ex) 495 nm and lambda(em) 515 nm. The calibration curve for FITC-ROP was linear over the range 0.25-20.0 or 50.0 microg/mL in all studied biosamples with correlation coefficients > 0.995. The inter-day and intra-day precisions of analysis were not more than 10%, and assay accuracy ranged from 93 to 105% for plasma and from 89 to 108% for tissue homogenates. This method has been confirmed here to be suitable for the study of pharmacokinetics and tissue distribution of ROP and the achieved results are highly instructive for the further pharmaceutical development of ROP, suggesting the promising application of the method to the increasingly important carbohydrate-based drugs.

Pharmacokinetics of anthraquinones in Xiexin decoction and in different combinations of its constituent herbs

Xiexin decoction (XXD), a classic pyretolysis formula, is composed of Rhei Rhizoma (DH), Radix Scutellaria (HQ) and Coptis Chinensis (HL) and is commonly used in the clinical setting. The aim of this study was to investigate the pharmacokinetic differences of the five anthraquinones in rats after oral administration of XXD and different combinations of its constituent herbs. Twenty rats were randomly divided into four groups and were administered one of the four extracts: DH, DH‐HQ, DH‐HL and XXD (DH‐HQ‐HL) via intragastric gavage. Anthraquinone concentrations in plasma were determined by an HPLC technique. Pharmacokinetic parameters were calculated from the plasma concentration–time data. Compared with DH alone, the DH‐HL combination decreased Cmax of all five anthraquinones and AUC of four anthraquinones (except physcion), and the DH‐HQ combination decreased AUC of aloe‐emodin and Cmax of rhein. Finally, XXD increased AUC of all five anthraquinones compared with DH‐HL combination. These results showed that the oral bioavailabilities of five anthraquinones were decreased significantly by combining DH with HL, whereas HQ weakened the effect of HL that inhibited the absorption of anthraquinones. Copyright

Pharmacokinetics, tissue distribution and metabolism of senkyunolide I, a major bioactive component in Ligusticum chuanxiong Hort. (Umbelliferae)

ETHNOPHARMACOLOGICAL RELEVANCE Ligusticum chuanxiong Hort. (Umbelliferae) is widely prescribed for treatment of cardiovascular diseases in China for centuries. One of the major bioactive components in L. chuanxiong is senkyunolide I (SEI), which shows pharmacological activities in anti-migraine and anti-oxidative damage. MATERIALS AND METHODS The aim of this study was to investigate in vivo pharmacokinetics, tissue distribution and metabolism of SEI in rats. The concentrations of SEI in plasma and tissues were determined by a high performance liquid chromatography (HPLC) method, and the pharmacokinetic parameters were calculated using and non-compartmental analysis. The metabolites were identified using high performance liquid chromatography tandem mass (HPLC-ESI-MS/MS) method. RESULTS After oral and intravenous administration, SEI was quickly eliminated from plasma and its oral bioavailability (BA) was about 37.25%, which was smaller than intraportal BA (81.17%), but similar to intraduodenal BA (36.91%), suggesting that gastric first-pass effect of SEI is negligible, and hepatic first-pass effect was approximately 18.83%. After oral administration, SEI could penetrate blood brain barrier and extensively distribute in tested tissues, with the descending order of AUC being kidney, liver, lung, muscle, brain, heart, thymus, and spleen in rat. The parent compound and nine metabolites were found and identified in rat bile after oral administration of SEI (36 mg/kg). The metabolic mechanism of SEI in rat mainly involves methylation, glucuronidation and glutathione conjugation during the phase II biotransformation pathway in rats. CONCLUSIONS The information gained here may provide a meaningful basis for clinical application of such a bioactive compound of herbal medicines.

Effect of metformin on the urinary metabolites of diet-induced-obese mice studied by ultra performance liquid chromatography coupled to time-of-flight mass spectrometry (UPLC-TOF/MS)

Obesity is becoming a health concern worldwide and metformin, a first line anti-diabetic drug, was associated with weight loss under different backgrounds. However, most researches focused on the anti-diabetic mechanism and less attention has been paid on the mechanism of weight loss of metformin. Therefore, we established a metabonomic method to evaluate metformin action in preventing obesity in a high fat diet-induced-obesity (DIO) mice model. 36 male C57BL/6 mice (8-week old) were randomly divided into control group (n=12, normal chow), model group (n=12, high fat chow) and metformin group (n=12, high fat chow and dosed with metformin) over 16 weeks. A urinary metabonomic study using UPLC-TOF/MS was performed in combination with multivariate statistical analysis. In addition, indices of body weight and food intake as well as fasting blood glucose, fed blood glucose, oral glucose tolerance test (OGTT) and plasma insulin were collected. Significant weight loss in metformin-treated mice was achieved and 21 potential biomarkers were identified. Decreased glucose, myristic acid, stearidonic acid, lysoPC (16:0), lysoPC (18:0), L-glutamic acid, L-methionine, L-threonine, L-phenylalanine, L-histidine, L-carnitine, L-malic acid and pantothenic acid in urine indicated that metformin may have exerted effects on energy metabolism. Further, based on the biomarkers, we cautiously propose that tricarboxylic acid cycle (TCA) may have been compromised by metformin and might contribute to the activation of adenosine monophosphate kinase (AMPK), then AMPK activation led to more β-oxidation of certain fatty acids and augmented lipolysis and thus induced weight loss. Related cellular and molecular studies are being considered to further investigate the underlying mechanism.