Unusual N-pyridinium amino acid-type alkaloids from roots and rhizomes of Sophora tonkinensis Gagnep.

Two previously undescribed amino acid-type alkaloids with unusual N-pyridinium cation (1-2) and six known alkaloids (3-8), were isolated from the roots and rhizomes of Sophora tonkinensis Gapnea. Their structures were characterized by UV, IR, NMR, and HRESIMS spectroscopic data. The absolute configurations of compounds 1 and 2 were established through comparison of their experimental ECD spectra to the theoretical spectra of 2 calculated by TDDFT method. The plausible biosynthetic pathway of pyridinium was also proposed. Moreover, compound 4 exhibited weak XOD inhibitory activity with the inhibition rate of 65.8% at concentration of 10 µM.

Multiflorumisides HK, stilbene glucosides isolated from Polygonum multiflorum and their in vitro PTP1B inhibitory activities.

A phytochemical study on a 70% EtOH extract of dried roots of Polygonum multiflorum resulted in the isolation of four undescribed stilbene glucosides, namely multiflorumisides HK (1-4). The structures of the natural products were elucidated by 1D and 2D nuclear magnetic resonance (NMR) as well as mass spectroscopy analyses. Among them, multiflorumiside J (3) and multiflorumiside K (4) belong to rare tetramer stilbene glucosides. Moreover, the in vitro inhibitory activities against protein tyrosine phosphatase 1B (PTP1B) were evaluated and the putative biosynthetic pathway was proposed. Notably, compounds 1-4 showed the inhibitory activity against PTP1B with the IC50 values of 1.2, 1.7, 1.5 and 4.6 µm, respectively. Based on the obtained results, stilbene glucosides could be the potential PTP1B inhibitors of P. multiflorum.

Identification of natural products as selective PTP1B inhibitors via virtual screening.

Protein tyrosine phosphatase 1B (PTP1B) is emerging as a promising yet challenging target for drug discovery. To identify natural products as new prototypes for PTP1B inhibitors, we employed a hierarchical protocol combining ligand-based and structure-based approaches for virtual screening against natural product libraries. Twenty-six compounds were prioritized for enzymatic evaluation against PTP1B, and ten of them were recognized as potent PTP1B inhibitors with IC50 values at the micromolar level. Notably, nine compounds demonstrated evident selectivity to PTP1B over four other PTPs, including the most homologous T-cell protein tyrosine phosphatase (TCPTP). The results implicated that the structural uniqueness of the natural products might be a potential solution to the selectivity issue associated with the target PTP1B.

a-Glucosidase inhibitors extracted from the roots of Polygonum multiflorum Thunb.

A novel stilbene glucoside, polygonumnolide D (1), and a novel dianthrone glycoside, polygonumnolide E (2), were isolated from a 70% EtOH extract of the dried roots of Polygonum multiflorum Thunb., together with six known compounds (3-8). Their structures were elucidated by 1D and 2D NMR as well as mass spectroscopy data. The isolated compounds were evaluated for their a-glucosidase inhibitory activities in vitro. Compounds 1, 2 and 5 showed the inhibitory activity against a-glucosidase with the IC50 values of 2.4, 2.7 and 0.3µM, respectively.

[Prescription of Jingdan Yimin for treatment of metabolic syndrome].

Based on the theory of traditional Chinese medicine, modern methods for drug investigation such as molecular targets in vitro and effects in vivo were used to study the prescription of Jingdan Yimin(JD), including selection of raw materials, composition, proportion, and effective dose of the compounds for treatment of metabolic syndrome. The IRF mice models, characterized by insulin resistance and hypercholesterolemia, were induced by high fat diet. The insulin sensitivity was estimated with insulin tolerance test(ITT) and glucose tolerance test(GTT); the levels of blood glucose and total cholesterol(TC), and the activities of α-glucosidase, protein tyrosine phosphatase 1B(PTP1B), and fructose phosphate amide transferase(GFAT)were measured with biochemical methods, respectively. The sample H13(h) extracted from Rhodiola crenulata, Y12(y) from Cordyceps militaris, and D(d) from Rheum palmatum were selected according to the inhibition activity on both PTP1B and α-glucosidase in vitro, regulation on hypercholesterolemia in IRF mice, and effects on GFAT activity, respectively; their synergistic effects on the treatment of metabolic syndrome were determined in IRF mice; composition proportion of h∶y∶d was measured in accordance with the results of L8(27) orthogonal experiments targeting on the inhibition of both PTP1B and α-glucosidase; finally, the effective dose was assessed based on the effects on IGT and hypercholesterolemia, respectively, in IRF mice. In conclusion, the prescription JD is composed by R. crenulata, C. militaris, and R. palmatum with the rate of 20∶1∶1, and its effective oral dose is 200 mg•kg⁻¹ for treatment of metabolic syndrome; its main mechanism is to inhibit the targets PTP1B and α-glucosidase. Monarch drug, R. crenulata, can clear away the lung-heat, tonify Qi, resolve stasis and nourish the heart. Adjuvant drug, C. militaris, can tonify the lung Qi and the kidney essence, strengthen waist and knee, accompanied with R. crenulata to enhance the function of invigorating lung and kidney. Assistant drug, rhubarb, can clear heat, detoxify, and remove blood stasis. These three herbs are compatible to show the effects of tonifying Qi, nourishing essence, clearing heat, reducing phlegm and resolving masses for the treatment of metabolic syndrome.

Effect of Hypericum perforatum L. extract on insulin resistance and lipid metabolic disorder in high-fat-diet induced obese mice.

Natural product Hypericum perforatum L. has been used in folk medicine to improve mental performance. However, the effect of H. perforatum L. on metabolism is still unknown. In order to test whether H. perforatum L. extract (EHP) has an effect on metabolic syndrome, we treated diet induced obese (DIO) C57BL/6J mice with the extract. The chemical characters of EHP were investigated with thin-layer chromatography, ultraviolet, high-performance liquid chromatography (HPLC), and HPLC-mass spectrometry fingerprint analysis. Oral glucose tolerance test (OGTT), insulin tolerance test (ITT), and the glucose infusion rate (GIR) in hyperinsulinemic-euglycemic clamp test were performed to evaluate the glucose metabolism and insulin sensitivity. Skeletal muscle was examined for lipid metabolism. The results suggest that EHP can significantly improve the glucose and lipid metabolism in DIO mice. In vitro, EHP inhibited the catalytic activity of recombinant human protein tyrosine phosphatase 1B (PTP1B) and reduced the protein and mRNA levels of PTP1B in the skeletal muscle. Moreover, expressions of genes related to fatty acid uptake and oxidation were changed by EHP in the skeletal muscle. These results suggest that EHP may improve insulin resistance and lipid metabolism in DIO mice.

[Investigation of a compound, compatibility of Rhodiola crenulata, Cordyceps militaris, and Rhum palmatum, on metabolic syndrome treatment. IV--Improving liver lipid accumulation].

To investigate the effects of a compound (FF16), compatibility of Rhodiola crenulata, Cordyceps militaris, and Rhum palmatum, on non-alcoholic fatty liver disease in IRF mice induced by high fat diet H&E stain was processed to evaluate the lipid accumulation in liver, and the dynamic microcirculation observation system was applied to determine hepatic microcirculation of IRF mice. Western blot was performed to evaluate IRS-2, HSL and ppar-alpha expression in liver. The results demonstrate that FF16 significantly decreased the liver lipid index and improved liver steatosis in IRF mice. Furthermore, FF16 could ameliorate hepatic microcirculation disturbance in IRF mice through enhancing RBC velocity and shear rates by 62.5% and 49.7%, increasing sinusoids perfusion by 70.0%, inhibiting adhered leukocytes in IRF mice. The abnormal expressions of IRS-2 and HSL were both reversed by the administration of FF16. In conclusion, FF16 could improve non-alcoholic fatty liver disease in IRF mice by improving insulin sensitivity, regulating lipid metabolism and improving microcirculation disturbance.

[Investigation of a compound, compatibility of Rhodiola crenulata, Cordyceps militaris, and Rheum palmatum, on metabolic syndrome treatment. V--Mechanisms on improving glucose metabolic disorders].

To investigate the mechanisms of a compound (FF16), compatibility of Rhodiola crenulata, Cordyceps militaris, and Rheum palmatum, on glucose metabolic disorders, the IRF mice charactered with insulin resistance and glucose metabolic disorders induced by high-fat diet in C57BL/6J mice were randomly divided into 3 groups; IRF, rosiglitazone (Rosi) and FF16. The glucose metabolism was evaluated by fasting blood glucose (FBG) levels and intraperitoneal glucose tolerance test (IPGTT). The insulin sensitivity was estimated by insulin tolerance test (ITT), fasting serum insulin levels and the index of HOMA-IR. The expressions of Akt and its phosphorylation levels, GSK3beta and its phosphorylation levels in liver were detected by Western Blot. The results showed that FF16 significantly improved the glucose metabolic disorders through reducing FBG by 15.1%, decreasing AUC values in glucose tolerance tests by 22.3%. FF16 significantly improved the insulin sensitivity through decreasing AUC values in insulin tolerance tests by 22.1%, reducing the levels of serum insulin by 42.9% and of HOMA-IR by 49.5%, comparing with model control, respectively. After the treatment with FF16, the levels of p-Akt and p-GSK3beta were increased by 116.4% and 24.9%, respectively, in the liver of IRF mice. In conclusion, compound FF16 could improve glucose metabolic disorders in IRF mice through enhancing the glyconeogenesis.

[Investigation of a compound, compatibility of Rhodiola crenulata, Cordyceps militaris, and Rheum palmatum on metabolic syndrome treatment III--controlling blood glucose].

Base on the improvement of compound FF16, compatibility of Rhodiola crenulata, Cordyceps militaris, and Rheum palmatum, on both insulin resistance and obesity, its effects on type 2 diabetes (T2DM ) was investigated here. The results showed that the levels of fasting and no-fasting blood glucose were controlled in the spontaneous type 2 diabetes KKAy mice; the impaired glucose tolerance (IGT)was improved by decreasing significantly the values of the glucose peaks and the area under the blood glucose-time curve (AUC ) after glucose-loading in glucose tolerance test (OGTT) in both high-fat-diet-induced pre-diabetes IRF mice and KKAy mice, respectively. The pancreatic histopathological analysis showed that the increased islet amount, the enlarged islet area, and the lipid accumulation in the pancreas were reversed by FF16 treatment in both IRF mice and KKAy mice. In the palmitate-induced RINm5f cell model, FF16 could effectively reduce the apoptosis and enhance the glucose-stimulated insulin secretion, respectively. In conclusion, FF16 could improve the T2DM by protecting the pancreatic beta-cells.

[Investigation of a compound, compatibility of Rhodiola crenulata, Cordyceps militaris, and Rheum palmatum, on metabolic syndrome treatment II - improving obesity].

To investigate the effect of compound FF16, compatibility of Rhodiola crenulata, Cordyceps militaris, and Rheum palmatum, on obesity, both the insulin resistant obese IRF mouse model induced by high fat diet and the spontaneous type 2 diabetes KKAy obese mouse model were used. The results showed that the body weights and the energy uptake were markedly reduced by compound FF16 in both IRF mice in dose-dependent manner and KKAy mice, respectively. Meanwhile, with the administration of FF16, the hypercholesterolemia and the hypertriglyceridemia were improved significantly in KKAy mice; and the levels of serum cholesterol and fatty index were decreased obviously, and the value of serum HDL-C was increased significantly in IRF mice, respectively. Moreover, the activity of a-glycosidase was inhibited by compound FF16 in vitro. In conclusion, FF16 could improve the obesity by inhibiting alpha-glycosidase activity.

[Investigation of compound, compatibility of Rhodiola crenulata, Cordyceps militaris, and Rhum palmatum, on metabolic syndrome treatment VI--improving hyperglycemia-mediated renal damage].

This study is to investigate the effects of a Chinese prescription (FF), compatibility of Rhodiola crenulata, Cordyceps militaris and Rheum palmatum, on nephropathy in type 1 diabetic rats induced by streptozocin. According to fasting blood glucose level, diabetic rats were divided into three groups: model group, insulin-treated group and FF-treated group. Parameters for evaluating the glucose & lipid metabolism and the renal function were monitored dynamically. Levels of oxidative stress were detected ten weeks later. The results show that FF could significantly decrease the level of serum glucose and lipid profiles, improve the renal functions by decreasing blood urea nitrogen, urine albumin excretion and urease activity; FF could also affect on oxidative stress. In conclusion, Chinese prescription FF could ameliorate hyperglycemia-mediated renal damage in type 1 diabetic rats. These effects may be related to its regulation on the metabolism of glucose and lipid, the microcirculation disturbance and the oxidative stress.

Rhein, an inhibitor of adipocyte differentiation and adipogenesis.

Rhein (RH), a compound purified from Radix et Rhizoma Rhei, has been used to alleviate liver and kidney damage. It is found that RH inhibited the differentiation of 3T3-L1 preadipocytes induced by differentiation medium in a time- and dose-dependent manner. It was revealed that RH downregulated the expression of adipogenesis-specific transcription factors PPARγ and C/EBPα, as well as their upstream regulator, C/EBPß. Furthermore, the PPARγ target genes that are involved in adipocyte differentiation, such as CD36, aP2, acyl CoA oxidase, uncoupled protein 2, acetyl-CoA carboxylase, and fatty acid synthase, were reduced after to RH. In addition, high-fat diet-induced weight gain and adiposity were reversed by RH in C57BL/6 mice. Consistent with the cells' results, RH downregulated the mRNA levels of PPARγ and C/EBPα, and their downstream target genes in C57BL/6 mice. Taken together, adipocyte differentiation and adipogenesis were inhibited by RH in cultured cells and in rodent models of obesity. The evidence implied that RH was a potential candidate for preventing metabolic disorders.

Improvement on lipid metabolic disorder by 3'-deoxyadenosine in high-fat-diet-induced fatty mice.

This study explores the effects of 3'-deoxyadenosine, a compound from Cordyceps militaris, on lipid metabolic disorder induced by a high-fat-diet in C57BL/6 mice. These mice had an obese body, lipid metabolic disorder and insulin resistance and were treated orally with 100 mg/kg/day 3'-deoxyadenosine (DA), 15 mg/kg/day rosiglitazone and 150 mg/kg/day fenofibrate, respectively. Compared to the model mice, the body weight gain in DA-treated mice were decreased by 66.5%, serum triglyceride and total cholesterol levels were decreased by 20.7% and 16.7%, respectively, and the triglyceride content in the skeletal muscle was reduced by 41.2%. This treatment also had a significant effect on insulin resistance. In DA-treated mice, the serum insulin levels and homeostasis model assessment of the insulin resistance index were decreased by 30% and 46%, respectively, and the areas under the glucose-time curve were depressed by 18% in the insulin tolerance test and by 21.5% in the oral glucose tolerance test. Finally, the value of glucose infusion rates and insulin induced-glucose uptake into the skeletal muscle in the hyperinsulinemic-euglycemic clamp test were increased by 18% and 41%, respectively, compared to those in the model mice. This data suggests that the effects of DA on lipid metabolic disorder induced by a high-fat-diet may be linked to its improvement on insulin resistance, especially concerning the increase of insulin sensitivity in the skeletal muscle.

[Studies on hypoglycemic effect of extract of Balaophora polyandra in mice].

OBJECTIVE: To study the hypoglycemic effect of the extract of B. polyandra (SHG). METHOD: The diabetic mice were induced by alloxan in ICR mice. The blood glucose concentration was measured by glucose oxidase method. The serum insulin level was determined by 125I-insulin radioimmunoassay kit. The hypoglycemic effect was evaluated by the levels of both fasting and no-fasting blood glucose. The effect on serum insulin level was estimated by the values of the blood insulin and the changes of the blood glucose induced by the glucose intraperitoneal injection. The effect on the glucose absorption was investigated by the oral sucrose or starch tolerance test. RESULT: Both of the fasting and no-fasting blood glucose levels were decreased significantly by the treatment of 20 or 30 g raw materials crude drug x kg (-1) SHG orally for 7-10 d in ICR mice or in alloxan diabetic mice. In the oral sucrose tolerance test or oral starch tolerance test, the administration of SHG reduced significantly the peak value of the blood glucose and the area under the blood glucose-time curve (AUC) in normal or alloxan diabetic mice, respectively. These effects of SHG were similar to those of acarbose, a kind of alpha-glucosidase inhibitors. In the oral glucose tolerance test in normal and alloxan diabetic mice, SHG decreased both the blood glucose peak and the AUC induced by the glucose loading. But in the intraperitoneal injection glucose tolerance test the levels of insulin in both SHG and control mice were similar, however, the changes of the blood glucose level after the glucose-loading for 30 min in SHG mice was much lower than that in control mice. CONCLUSION: With the treatment of SHG, the fasting and no-fasting blood glucose concentrations were decreased and the glucose tolerance improved significantly in both normal and alloxan diabetic mice, and the inhibition of a-glucosidase might be one of its major mechanisms.