Mulberry leaf extract restores arterial pressure in streptozotocin-induced chronic diabetic rats

A Comparison of Food-grade Folium mori ( Sāng Yè) Extract and 1-Deoxynojirimycin for Glycemic Control and Renal Function in Streptozotocin-induced Diabetic Rats

Folium mori ( Sāng Yè, leaf of Morus alba L.; FM) is known to possess hypoglycemic effects, and 1-deoxynojirimycin (1-DNJ) has been proposed as an important functional compound in FM. However, the hypoglycemic activity of purified 1-DNJ has been rarely studied. It is also not known how FM and 1-DNJ affect the development of DM nephropathy. This study compared the antidiabetic effect of a commercial FM product with that of purified 1-DNJ in streptozotocin-induced diabetic rats. Seven days after induction, the diabetic rats were gavaged with FM (1, 3, 10, and 30 mg/kg/day), 1-DNJ (30 mg/kg/day), or vehicle (distilled deionized water; 2 ml/kg/day) for 7 days. All doses of FM ameliorated fasting and post-prandial blood glucose concomitantly with an increase in peripheral and pancreatic levels of insulin and improved homeostasis model assessment (HOMA-IR) in diabetic rats in a dose-dependent manner. Increased thiobarbituric acid reactive substances (TBARS) and nitrate/nitrite levels in the kidney, liver, and muscle of diabetic rats were reversed by all doses of FM. The renal function of the diabetic rats was normalized by all doses of FM, while blood pressure changes were reversed by FM at doses of 3 mg/kg and above. Moreover, most of the above-mentioned parameters were improved by FM at doses of 3 mg/kg and above to a similar extent as that of 1-DNJ. The results showed superior antidiabetic potential of the commercial FM product for glycemic control and protection against the development of diabetic nephropathy.

Antiplatelet Activity of Morus alba Leaves Extract, Mediated via Inhibiting Granule Secretion and Blocking the Phosphorylation of Extracellular-Signal-Regulated Kinase and Akt

Ethnopharmacological Relevance. Morus alba L. leaves (MAE) have been used in fork medicine for the treatment of beriberi, edema, diabetes, hypertension, and atherosclerosis. However, underlying mechanism of MAE on cardiovascular protection remains to be elucidated. Therefore, we investigated whether MAE affect platelet aggregation and thrombosis. Materials and Methods. The anti-platelet activity of MAE was studied using rat platelets. The extent of anti-platelet activity of MAE was assayed in collagen-induced platelet aggregation. ATP and serotonin release was carried out. The activation of integrin α_IIbβ₃ and phosphorylation of signaling molecules, including MAPK and Akt, were investigated with cytofluorometer and immunoblotting, respectively. The thrombus formation in vivo was also evaluated in arteriovenous shunt model of rats. Results. HPLC chromatographic analysis revealed that MAE contained rutin and isoquercetin. MAE dose-dependently inhibited collagen-induced platelet aggregation. MAE also attenuated serotonin secretion and thromboxane A₂ formation. In addition, the extract in vivo activity showed that MAE at 100, 200, and 400 mg/kg significantly and dose-dependently attenuated thrombus formation in rat arterio-venous shunt model by 52.3% (P < 0.001), 28.3% (P < 0.01), and 19.1% (P < 0.05), respectively. Conclusions. MAE inhibit platelet activation, TXB2 formation, serotonin secretion, aggregation, and thrombus formation. The plant extract could be considered as a candidate to anti-platelet and antithrombotic agent.

Iron oxide impregnated Morus alba L. fruit peel for biosorption of Co(II): biosorption properties and mechanism

Biosorption is an ecofriendly wastewater treatment technique with high efficiency and low operating cost involving simple process for the removal of heavy metal ions from aqueous solution. In the present investigation, Morus alba L. fruit peel powder (MAFP) and iron oxide impregnated Morus alba L. fruit peel powder (IO-MAFP) were prepared and used for treating Co(II) contaminated aqueous solutions. Further the materials were characterized by using FTIR and SEM-EDX analysis. From FT-IR analysis it was found that hydroxyl, methoxy, and carbonyl groups are responsible for Co(II) biosorption. The kinetic data obtained for both biosorbents was well fitted with pseudo-second-order kinetic model. The equilibrium data was in tune with the Langmuir and Freundlich isotherm models. The thermodynamic studies were also carried and it was observed that sorption process was endothermic at 298–328 K. These studies demonstrated that both biosorbents were promising, efficient, economic, and biodegradable sorbents.

1-deoxynojirimycin inhibits glucose absorption and accelerates glucose metabolism in streptozotocin-induced diabetic mice

We investigated the role of 1-deoxynojirimycin (DNJ) on glucose absorption and metabolism in normal and diabetic mice. Oral and intravenous glucose tolerance tests and labeled ¹³C₆-glucose uptake assays suggested that DNJ inhibited intestinal glucose absorption in intestine. We also showed that DNJ down-regulated intestinal SGLT1, Na⁺/K⁺-ATP and GLUT2 mRNA and protein expression. Pretreatment with DNJ (50 mg/kg) increased the activity, mRNA and protein levels of hepatic glycolysis enzymes (GK, PFK, PK, PDE1) and decreased the expression of gluconeogenesis enzymes (PEPCK, G-6-Pase). Assays of protein expression in hepatic cells and in vitro tests with purified enzymes indicated that the increased activity of glucose glycolysis enzymes was resulted from the relative increase in protein expression, rather than from direct enzyme activation. These results suggest that DNJ inhibits intestinal glucose absorption and accelerates hepatic glucose metabolism by directly regulating the expression of proteins involved in glucose transport systems, glycolysis and gluconeogenesis enzymes.

Cooperative anti-diabetic effects of deoxynojirimycin-polysaccharide by inhibiting glucose absorption and modulating glucose metabolism in streptozotocin-induced diabetic mice

We had previously shown that deoxynojirimycin-polysaccharide mixture (DPM) not only decreased blood glucose but also reversed the damage to pancreatic β-cells in diabetic mice, and that the anti-hyperglycemic efficacy of this combination was better than that of 1-deoxynojirimycin (DNJ) or polysachharide alone. However, the mechanisms behind these effects were not fully understood. The present study aimed to evaluate the therapeutic effects of DPM on streptozotocin (STZ)-induced diabetic symptoms and their potential mechanisms. Diabetic mice were treated with DPM (150 mg/kg body weight) for 90 days and continued to be fed without DPM for an additional 30 days. Strikingly, decrease of blood glucose levels was observed in all DPM treated diabetic mice, which persisted 30 days after cessation of DPM administration. Significant decrease of glycosylated hemoglobin and hepatic pyruvate concentrations, along with marked increase of serum insulin and hepatic glycogen levels were detected in DPM treated diabetic mice. Results of a labeled (13)C6-glucose uptake assay indicated that DPM can restrain glucose absorption. Additionally, DPM down-regulated the mRNA and protein expression of jejunal Na(+)/glucose cotransporter, Na(+)/K(+)-ATPase and glucose transporter 2, and enhanced the activities as well as mRNA and protein levels of hepatic glycolysis enzymes (glucokinase, phosphofructokinase, private kinase and pyruvate decarboxylas E1). Activity and expression of hepatic gluconeogenesis enzymes (phosphoenolpyruvate carboxykinase and glucose-6-phosphatase) were also found to be attenuated in diabetic mice treated with DPM. Purified enzyme activity assays verified that the increased activities of glucose glycolysis enzymes resulted not from their direct activation, but from the relative increase in protein expression. Importantly, our histopathological observations support the results of our biochemical analyses and validate the protective effects of DPM on STZ-induced damage to the pancreas. Thus, DPM has significant potential as a therapeutic agent against diabetes.

Peril in the market-classification and dosage of species used as anti-diabetics in Lima, Peru

BACKGROUND

Peru is what Peruvian anthropologist Lupe Camino calls the “health axis” of the old Central Andean culture area stretching from Ecuador to Bolivia. In particular in the North of the country the traditional use of medicinal dates back as far as the first millennium B.C. Both healers, and the wider population, often buy their medicinal plants in local markets, but there is very little comparative information available about which plants are sold under which vernacular name at any given time, for which indication, and which dosage information and information about side effects is given by vendors. For this study we used two traditionally used species groups “Hercampuri” Gentianella spec. (Gentianaceae) and “Pasuchaca” Geranium spec. (Geraniaceae.), found in the Mercado Aviación in Lima, as small, clearly circumscribed plant group frequently used to treat symptoms of diabetes as a test case to study the taxonomy, indications, dosage, indicated side effects, and additional species used as admixtures and hypothesized that: 1. A wide variety of different species is sold under the same common name, and often several common names exist for one species. 2. There is no consistency in the dosage, or a relationship between dosage and species marketed under one name. 3. However, there is consistency in the knowledge about usage and side effects.

METHODS

Surveys focusing on medicinal plants sold and their properties were conducted at the Mercado Aviaciónin Lima in December 2012. Vouchers of all specimens were deposited at the National Herbarium of Peru.

RESULTS AND CONCLUSIONS

Our surveys in Mercado Aviación in Lima yielded four species of Gentianella, two of Geranium, and three additional species from three genera used as common additives that were sold as anti-diabetic. These results indicate that even in case of only a few plant species, used for a very clearly circumscribed application, patients run a considerable risk when purchasing their remedies in the market. The possible side effects in this case are the more serious because diabetes has to be treated long term, and as such the patients are ingesting possible toxic remedies over a long period of time. Much more control, and a much more stringent identification of the material sold in public markets, and entering the global supply chain via internet sales, would be needed.

Mulberry leaf extract increases adiponectin in murine 3T3-L1 adipocytes

We have previously shown that mulberry leaf extract (MA) causes blood glucose levels to decrease in rats with streptozotocin-induced diabetes while enhancing glucose uptake by isolated fat cells. We hypothesized that the antidiabetic activity of MA is mediated via enhancement of adiponectin secretion and adipogenesis, which consequently decreases blood glucose. In the present study, we aimed to elucidate the molecular basis for the observed antidiabetic activity using murine 3T3-L1 preadipocyte cultures. We found that treatment of differentiating 3T3-L1 cells with MA at concentrations of 5, 15, and 45 μg/mL increased expression of adiponectin messenger RNA from 1.4-fold (control) to 1.5-, 1.95-, and 2.2-fold above basal values, respectively, while causing adiponectin secretion to increase from 70 ± 7.4 ng/mL to 100 ± 1.4, 138 ± 2.0, and 176 ± 21.4 ng/mL, respectively. Furthermore, we observed an increase in both lipid accumulation and messenger RNA expression of transcription factors, such as CCAAT/enhancer-binding protein α and peroxisome proliferator-activated receptor γ; and of the fatty acid-binding protein aP2 in differentiated 3T3-L1 cells pretreated with MA. Our findings indicate that the stimulatory effects of mulberry leaf extract on adipocyte proliferation and differentiation likely occur through up-regulation of adipogenic transcription factors and downstream gene expression. Such effects of mulberry leaf extract on adiponectin secretion and adipocyte activity may account for, at least in part, the antidiabetic effects of consumption of beverages containing mulberry leaves.

Hypotensive, Hypolipidemic, and Vascular Protective Effects of Morus alba L. in Rats Fed an Atherogenic Diet

Morus alba L. has been used in traditional Chinese medicine and almost all parts of this plant are useful in cardiovascular, liver and spleen disorders. The present study was designed to investigate the inhibitory effect of a water extract from Morus alba L. (WMA) on vascular dysfunction in rat models fed a high fat and high cholesterol diet. Male rats were fed an atherogenic diet consisting of food with 7.5% cocoa butter and 1.25% cholesterol, with or without 100 or 200 mg/day/kg WMA, for 14 weeks. Chronic treatment with low (100 mg/kg/day) or high (200 mg/day/kg) doses of WMA markedly attenuated hypertension and the impairments of acetylcholine-induced relaxation of aortic rings in rats fed an atherogenic diet. WMA reduced intima/media thickness in rats fed an atherogenic diet. WMA improved plasma levels of triglyceride (TG) and augmented plasma levels of high-density lipoprotein (HDL) and plasma low-density lipoprotein (LDL), but did not affect blood glucose levels. Interestingly, WMA suppressed increased cell adhesion molecules such as E-selectin, vascular cell adhesion molecule-1 (VCAM-1), and intracellular adhesion molecule-1 (ICAM-1) expression in the aorta. Taken together, these results suggested that Morus alba L. could improve an atherogenic diet-induced hypertension, hyperlipidemia, and vascular dysfunction through inhibition of cell adhesion molecules expression and induction of vascular relaxation.

Hybrid of 1-deoxynojirimycin and polysaccharide from mulberry leaves treat diabetes mellitus by activating PDX-1/insulin-1 signaling pathway and regulating the expression of glucokinase, phosphoenolpyruvate carboxykinase and glucose-6-phosphatase in alloxan-induced diabetic mice

ETHNOPHARMACOLOGICAL RELEVANCE

1-Deoxynojirimycin (DNJ) discovered from mulberry trees has been reported to be a potent inhibitor of intestinal α-glycosidases (sucrase, maltase, glucoamylase), and many polysaccharides were useful in protecting against alloxan-induced pancreatic islets damage through their scavenging ability. This study was aimed to evaluate the therapeutic effect and potential mechanism(s) of the hybrid of DNJ and polysaccharide (HDP) from mulberry leaves on alloxan-induced diabetic mice.

MATERIALS AND METHODS

Daily oral treatment with HDP (150 mg/kg body weight) to diabetic mice for 12 weeks, body weight and blood glucose were determined every week, oral glucose tolerance test was performed after 4 and 8 weeks, biochemical values were measured using assay kits and gene expressions were investigated by RT-PCR.

RESULTS

A significant decline in blood glucose, glycosylated hemoglobin, triglyceride, aspartate transaminase and alanine transaminase levels and an evident increase in body weight, plasma insulin level and high density lipoprotein were observed in HDP treated diabetic mice. The polysaccharide (P1) showed a significant scavenging hydroxyl radicals and superoxide anion radical effects in vitro, which indicated that P1 could protect alloxan-induced pancreatic islets from damage by scavenging the free radicals and repaired the destroyed pancreatic β-cells. Pharmacokinetics assay showed that DNJ could be absorbed from the gastrointestinal mucosa and diffused rapidly into the liver, resulted in postprandial blood glucose decrease and alleviated the toxicity caused by sustained supra-physiological glucose to pancreatic β-cells. RT-PCR results indicated that HDP could modulate the hepatic glucose metabolism and gluconeogenesis by up/down-regulating the expression of rate-limiting enzymes (glucokinase, phosphoenolpyruvate carboxykinase and glucose-6-phosphatase) in liver and up-regulating the pancreatic and duodenal homeobox factor-1 (PDX-1), insulin-1 and insulin-2 expressions in pancreas.

CONCLUSION

These findings suggested that HDP has complimentary potency to develop an antihyperglycemic agent for treatment of diabetes mellitus.

Mulberry leaf polyphenols possess antiatherogenesis effect via inhibiting LDL oxidation and foam cell formation

Oxidized low-density lipoprotein (ox-LDL) and its uptake by machrophage are the hallmark in atherogenesis. In the present study, we aimed to investigate the antiatherogenic effect of mulberry leaf extracts (MLE) and the polyphenolic extracts (MLPE), which contained polyphenols including quercetin (11.70%), naringenin (9.01%) and gallocatechin gallate (10.02%). Both MLE and MLPE inhibited the oxidation and lipid peroxidation of LDL, while MLPE was shown to be more potent. As 1.0 mg/mL MLE reduced 30% of ox-LDL-generated ROS, 0.5 mg/mL MLPE decreased 46% of the ROS and was shown to be more potent on elevating SOD-1 and GPx in macrophages. At the same dose of 0.5 mg/mL, MLPE exhibited 1.5-fold potency than MLE in decreasing the formation of foam cells. Both MLE and MLPE reduced the expression of PPARγ, CD36 and SR-A, implicating the molecular regulation on ox-LDL uptake. These results suggested that MLPE potentially could be developed as an antiatherogenic agent and deserve further investigation.