Water extracts from Momordica charantia increase glucose uptake and adiponectin secretion in 3T3-L1 adipose cells

Bitter melon extract suppresses metastatic breast cancer cells (MCF-7 cells) growth possibly by hindering glucose uptake

Breast cancer is one of the most commonly diagnosed cancers among women, however the complete cure for metastatic breast cancer is lacking due to poor prognosis. There has been an increasing trend of dietary modifications including consumption of natural food for the prevention of cancer. One of the popular natural foods is bitter melon. Bitter melon grows in tropical and subtropical areas. Some of the beneficial effects of bitter melon towards disease including cancer have been reported at the whole body/organismal level. However, specific cellular mechanisms by which bitter melon exerts beneficial effects in breast cancer are lacking. In this study, we used a human metastatic breast cancer cell line, MCF-7 cell, to study if bitter melon alters glucose clearance from the culture medium. We co-cultured MCF-7 cells with bitter melon extract in the presence and absence of supplemented insulin and subsequently measured MCF-7 cells viability. In this study, we report a noble finding that bitter melon extract exerts cytotoxic effects on MCF-7 cells possibly via inhibition of glucose uptake. Our findings show that insulin rescues MCF-7 cells from the effects of bitter melon extract.

D-optimal mixture design optimized solid formulation containing fruits extracts of Momordica charantia and Abelmoschus esculentus

Fruit extracts of Momordica charantia L. (Cucurbitaceae) and Abelmoschus esculentus (L.) Moench (Malvaceae) have shown promising antidiabetic activities in clinical trials. However, they remain underutilized due to insufficient standardization and lack of formulation containing their mixture. This study’s overall purpose was to develop and optimize a capsule dosage form containing dried fruit extracts of M. charantia and A. esculentus. The design of the experiment involved two steps; first, response surface methodology (RSM) with a five-level two-factor central composite rotatable design (CCRD) was employed to determine the optimal dose of a mixture of extracts for adequate glycemic control. The extract of M. charantia and A. esculentus were the independent variables while fasting plasma glucose (FPG) was the dependent factor. In the second step, a D-optimal mixture design was applied to study the interaction effect of the optimal dose and selected excipients on granules flowability and capsules’ disintegration time. Moreover, a second-order quadratic model determined the interrelationship of excipients and the desired capsules’ quality attributes. The validity of the predicted models was confirmed. The findings indicated that a combined dose of 175 A. esculentus and 281 M. charantia (mg/kg) significantly reduced the FPG level compared to vehicle at day 14 (mean difference -2.7 ± 0.21, p < 0.001). This dose was used to make a 600 mg capsule (DM083) with 76% drug loading. The DM083 had 40.4 ± 0.62 mg GAE/gDW total polyphenols, 12 peaks HPLC fingerprint, and 26.6 ± 4.75 min average disintegration time. Together, these findings showed that a mixture of M. charantia and A. esculentus fruit extracts could be formulated in a stable capsule dosage form with acceptable quality standards. Further biological studies such as toxicity assays and long-term efficacy studies of the developed capsules could be carried out before large-scale commercial production.

Virtual screening of functional foods and dissecting their roles in modulating gene functions to support post COVID-19 complications

COVID-19 has become the focal point since 2019 after the outbreak of coronavirus disease. Many drugs are being tested and used to treat coronavirus infections; different kinds of vaccines are also introduced as preventive measure. Alternative therapeutics are as well incorporated into the health guidelines of some countries. This research aimed to look into the underlying mechanisms of functional foods and how they may improve the long-term post COVID-19 cardiovascular, diabetic, and respiratory complications through their bioactive compounds. The potentiality of nine functional foods for post COVID-19 complications was investigated through computational approaches. A total of 266 bioactive compounds of these foods were searched via extensive literature reviewing. Three highly associated targets namely troponin I interacting kinase (TNNI3K), dipeptidyl peptidase 4 (DPP-4), and transforming growth factor beta 1 (TGF-β1) were selected for cardiovascular, diabetes, and respiratory disorders, respectively, after COVID-19 infections. Best docked compounds were further analyzed by network pharmacological tools to explore their interactions with complication-related genes (MAPK1 and HSP90AA1 for cardiovascular, PPARG and TNF-alpha for diabetes, and AKT-1 for respiratory disorders). Seventy-one suggested compounds out of one-hundred and thirty-nine (139) docked compounds in network pharmacology recommended 169 Gene Ontology (GO) items and 99 Kyoto Encyclopedia of Genes and Genomes signaling pathways preferably AKT signaling pathway, MAPK signaling pathway, ACE2 receptor signaling pathway, insulin signaling pathway, and PPAR signaling pathway. Among the chosen functional foods, black cumin, fenugreek, garlic, ginger, turmeric, bitter melon, and Indian pennywort were found to modulate the actions. Results demonstrate that aforesaid functional foods have attenuating roles to manage post COVID-19 complications. PRACTICAL APPLICATIONS: Functional foods have been approaching a greater interest due to their medicinal uses other than gastronomic pleasure. Nine functional food resources have been used in this research for their traditional and ethnopharmacological uses, but their directive-role in modulating the genes involved in the management of post COVID-19 complications is inadequately studied and reported. Therefore, the foods types used in this research may be prioritized to be used as functional foods for ameliorating the major post COVID-19 complications through appropriate science.

Bioanalytical method development for momordicinin and its application to long-term pharmacokinetics in diabetic rats

OBJECTIVE

To develop and validate bioanalytical RP-HPLC method to evaluate pharmacokinetics and tissue distribution pattern of momordicinin (MRN).

SIGNIFICANCE

MRN is one of the major cucurbitane triterpenoid found in Momordica charantia Linn (MC). However, MRN has not been explored for its pharmacokinetic profile, tissue distribution, and stability in order to establish it as an antidiabetic agent.

METHODS

In 28 days pharmacokinetic study, 54 diabetic male wistar rats were divided into three different groups and administered with 25, 50, and 100 mg/kg MRN orally. The blood samples were collected at 1, 7, 14, 21, and 28th day of the treatment and plasma quantification of MRN was done by validated RP-HPLC method. The rats were sacrificed at end of the study for tissue distribution.

RESULTS

The developed method was successfully applied to investigate pharmacokinetic profile of MRN. In pharmacokinetic analysis, the C_max for 25, 50, and 100 mg/kg was found to be 8.412, 10.443, and 11.829 µg/mL respectively suggesting the dose dependent activity. The maximum plasma concentration was achieved at 2 h for all doses. MRN showed major distribution in liver followed by kidney, spleen, and pancreas.

CONCLUSION

The newly developed and validated method was used to assay MRN in plasma as well as in tissues to evaluate pharmacokinetics of the drug for the first time. Undoubtedly, these findings can be taken into consideration while concluding its therapeutic effects after oral administration.

Natural Compound 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al from Momordica charantia Acts as PPARγ Ligand

Momordica charantia is a popular vegetable associated with effective complementary and alternative diabetes management in some parts of the world. However, the molecular mechanism is less commonly investigated. In this study, we investigated the association between a major cucurbitane triterpenoid isolated from M. charantia, 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al (THCB) and peroxisome proliferator activated receptor gamma (PPARγ) activation and its related activities using cell culture and molecular biology techniques. In this study, we report on both M. charantia fruit crude extract and THCB in driving the luciferase activity of Peroxisome Proliferator Response Element, associated with PPARγ activation. Other than that, THCB also induced adipocyte differentiation at far less intensity as compared to the full agonist rosiglitazone. In conjunction, THCB treatment on adipocytes also resulted in upregulation of PPAR gamma target genes expression; AP2, adiponectin, LPL and CD34 at a lower magnitude compared to rosiglitazone's induction. THCB also induced glucose uptake into muscle cells and the mechanism is via Glut4 translocation to the cell membrane. In conclusion, THCB acts as one of the many components in M. charantia to induce hypoglycaemic effect by acting as PPARγ ligand and inducing glucose uptake activity in the muscles by means of Glut4 translocation.

Pharmacological reflection of plants traditionally used to manage diabetes mellitus in Tanzania

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing national prevalence of diabetes mellitus (DM) and its complications have overstretched the health care system in Tanzania and influenced patients to use herbal medicines as alternative therapeutic strategies. Therefore, an urgent need exists to validate the safety and efficacy of plants used locally.

AIM OF THE STUDY

To identify plants used for the management of DM in Tanzania and analyses their pharmacological, phytochemistry, and safety evidence with a special focus on the mechanism of action.

METHODS

Researchers searched Medline, web of science, and Scopus for published articles. Also, specialized herbarium documents of Muhimbili Institute of traditional medicine were reviewed. Articles were assessed for relevance, quality, and taxonomical accuracy before being critically reviewed.

RESULTS

We identified 62 plant species used locally for DM management. Moringa oleifera Lam. and Cymbopogon citratus (D.C) stapf were the most mentioned. Fifty-four phytochemicals from 13 species had DM activities. These were mainly; polyphenolics, phytosterols, and triterpenoids. Extracts, fractions, and pure compounds from 18 species had in vitro antidiabetic activities of which 14 had α-glucosidase and α-amylase inhibition effects. The most studied -Momordica charantia L. increased; glucose uptake and adiponectin release in 3T3-L1 adipocytes, insulin secretion, insulin receptor substrate-1 (IRS-1), GLUT-4 translocation, and GLP-1 secretion; and inhibited protein tyrosine phosphatase 1 B (PTP1B). Preclinical studies reported 30 species that lower plasma glucose with molecular targets in the liver, skeletal muscles, adipose tissues, pancreases, and stomach. While three species; Aspilia mossambiscensis (Oliv.) Willd, Caesalpinia bonduc (L.) Roxb, and Phyllanthus amarus Schumach. & Thonn. had mild toxicity in animals, 33 had no report of their efficacy in DM management or toxicity.

CONCLUSION

Local communities in Tanzania use herbal medicine for the management of DM. However, only a fraction of such species has scientific evidence. A. mossambiscensis, C. bonduc., and P. amarus had mild toxicity in animals. Together, our findings call for future researches to focus on in vitro, in vivo, and phytochemical investigation of plant species for which their use in DM among the local communities in Tanzania have not been validated.

The Effect of Coconut Water on Adipocyte Differentiation and Lipid Accumulation in 3T3-L1 Cells

Coconut water is reported to have lipid-lowering effects in animal studies. However, there is lack of published reports regarding its effect on adipocytes. This study observed the effect of coconut water on adipocyte differentiation and lipid accumulation in 3T3-L1 cells. The sample used in this study was mature coconut water from tall variety. Based on a preliminary study, the sample was heat-treated and added with certain amino acids as precursors for Maillard reaction to improve its original flavor. As a comparison, aromatic coconut water was used since it is highly preferred as a fresh beverage. Six samples were supplemented to 3T3-L1 cells, which were then analyzed for cell proliferation, lipid accumulation, triglyceride content, and gene expression. Arginine and vitamin C contents of the samples were also determined. The data were analyzed with ANOVA and followed by Tukey's test. Results showed that aromatic coconut water could slightly suppress lipid accumulation, while mature coconut water had a significantly lower percentage of accumulation compared to the control sample (p<0.05). Canned and fresh samples had no significant difference in terms of lipid-lowering activity (p>0.05). Similarly, the addition of lysine and proline in canned samples did not significantly affect the cells' differentiation. There was no significant effect on expressions of C/EBP-α and PPARγ, indicating the possibility of other pathways involved in hypolipidemic effect of coconut water. This study showed that coconut water might have potential to inhibit adipogenesis in 3T3-L1 cells due to its bioactive compounds.

The safety and efficacy of Momordica charantia L. in animal models of type 2 diabetes mellitus: A systematic review and meta-analysis

Type 2 diabetes mellitus is a chronic hyperglycemic condition due to progressively impaired glucose regulation. Momordica charantia L. could potentially improve hyperglycemia because its fruit extracts can alleviate insulin resistance, beta-cell dysfunction, and increase serum insulin level. We evaluated the effect of M. charantia L. in comparison with a vehicle on glycemic control in animal models of type 2 diabetes mellitus. MEDLINE, Web of Science, Scopus, and CINAHL databases were searched without language restriction through April 2019. About 66 studies involving 1861 animals that examined the effect of M. charantia L. on type 2 diabetes mellitus were included. Fruits and seed extracts reduced fasting plasma glucose (FPG) and glycosylated hemoglobin A1c in comparison to vehicle control: (42 studies, 815 animals; SMD, -6.86 [95% CI; -7.95, -5.77], 3 studies, 59 animals; SMD; -7.76 [95% CI; -12.50, -3.01]) respectively. Also, the extracts have hepato-renal protective effects at varying doses and duration of administration. Despite the observed significant glycemic control effect, poor methodological quality calls for future researches to focus on standardizing extract based on chemical markers and adopt measures to improve the quality of preclinical studies such as sample size calculation, randomization, and blinding.

The Role of Momordica charantia in Resisting Obesity

Momordica charantia (M. charantia), commonly known as bitter gourd, bitter melon, kugua, balsam pear, or karela, is a tropical and sub-tropical vine belonging to the Cucurbitaceae family. It has been used to treat a variety of diseases in the traditional medicine of China, India, and Sri Lanka. Here, we review the anti-obesity effects of various bioactive components of M. charantia established at the cellular and organismal level. We aim to provide links between various bioactive components of M. charantia and their anti-obesity mechanism. An advanced search was conducted on the worldwide accepted scientific databases via electronic search (Google Scholar, Web of Science, ScienceDirect, ACS Publications, PubMed, Wiley Online Library, SciFinder, CNKI) database with the query TS = “Momordica charantia” and “obesity”. Information was also obtained from International Plant Names Index, Chinese Pharmacopoeia, Chinese herbal classic books, online databases, PhD and MSc dissertations, etc. First, studies showing the anti-obesity effects of M. charantia on the cells and on animals were classified. The major bioactive components that showed anti-obesity activities included proteins, triterpenoids, saponins, phenolics, and conjugated linolenic acids. Their mechanisms included inhibition of fat synthesis, promotion of glucose utilization, and stimulation of auxiliary lipid-lowering activity. Finally, we summarized the risks of excessive consumption of M. charantia and the application. Although further research is necessary to explore various issues, this review establishes the therapeutic potential of M. charantia and it is highly promising candidate for the development of anti-obesity health products and medicines.

In vitro and in silico elucidation of antidiabetic and anti-inflammatory activities of bioactive compounds from Momordica charantia L

Bitter melon (Momordica charantia) has been used to manage diabetes and related conditions in various parts of the world. In the present study, ten compounds were isolated from acetone and methanol extracts of bitter melon. The chemical structures of compounds were unambiguously elucidated by 1D, 2D NMR, and high-resolution mass spectra. Identified compounds 1-7 exhibited significant inhibition of α-amylase and moderate inhibition of α-glucosidase activities. Momordicoside G and gentisic acid 5-O-β-d-xyloside showed the highest inhibition of α-amylase (70.5%), and α-glucosidase (56.4%), respectively. Furthermore, molecular docking studies of isolated compounds 1-7 were able to bind to the active sites of both enzymes. Additionally, the isolated compounds 1-7 significantly attenuated lipopolysaccharide (LPS)-induced inflammation, downregulating the expression of pro-inflammatory markers NF-κB, INOS, IL-6, IL-1β, TNF-α, and Cox-2 in murine macrophage RAW 264.7 cells. One phenolic derivative, gentisic acid 5-O-β-d-xyloside, was isolated and identified for the first time from bitter melon, and significantly suppressed the expression of Cox-2 and IL-6 compared to the LPS-treated group. α-Amylase and α-glucosidase are targets of anti-diabetes drugs, our findings suggest that compounds purified from bitter melon may have potential to use as functional food ingredients for the prevention of type 2 diabetes and related inflammatory conditions.

Hypoglycaemic effects of functional tri-peptides from silk in differentiated adipocytes and streptozotocin-induced diabetic mice

BACKGROUND

In this study, the tri-peptides Gly-Glu-Tyr (GEY) and Gly-Tyr-Gly (GYG), identified previously as active compounds from the silk peptide E5K6, significantly stimulated basal and insulin-mediated glucose uptake by 3T3-L1 fibroblasts in a dose-dependent manner.

RESULTS

Synthetic GEY and GYG peptides at a concentration of 500 µmol L(-1) significantly increased glucose transporter type 4 expression by 157% and 239%, respectively. Differentiation of 3T3-L1 cells into adipocytes leads to accumulation of intracellular fat droplets, and GEY and GYG at a concentration of 250 µmol L(-1) suppressed this effect by 72% and 75%, respectively. GYG improved glucose tolerance in steptozotocin (STZ)-induced diabetic mice in a dose-dependent manner.

CONCLUSION

These results suggest that GYG isolated from E5K6 has anti-diabetic potential and silk waste products containing bioactive peptides could be used to the developments of treatments to lower blood glucose.

A review on possible therapeutic targets to contain obesity: The role of phytochemicals

The prevalence and severity of obesity has increased markedly in recent decades making it a global public health concern. Since obesity is a potential risk factor in the development of hypertension, type-2 diabetes, cardiovascular diseases, infertility, etc., it is no more viewed as a cosmetic issue. Currently, only a few FDA-approved anti-obesity drugs like Orlistat, Lorcaserin and Phentermine-topiramate are available in the market, but they have considerable side effects. On the other hand, bariatric surgery as an alternative is associated with high risk and expensive. In view of these there is a growing trend towards natural product-based drug intervention as one of the crucial strategies for management of obesity and related ailments. In Asian traditional medicine and Ayurvedic literature a good number of plant species have been used and quoted for possible lipid-lowering and anti-obesity effects; however, many of them have not been evaluated rigorously for a definite recommendation and also lack adequate scientific validation. This review explores and updates on various plant species, their used parts, bioactive components and focuses multiple targets/pathways to contain obesity which may pave the way to develop novel and effective drugs. We also summarised different drugs in use to treat obesity and their current status. Nature is future promise of our wellbeing.

Beneficial role of bitter melon supplementation in obesity and related complications in metabolic syndrome

Diabetes, obesity, and metabolic syndrome are becoming epidemic both in developed and developing countries in recent years. Complementary and alternative medicines have been used since ancient era for the treatment of diabetes and cardiovascular diseases. Bitter melon is widely used as vegetables in daily food in Bangladesh and several other countries in Asia. The fruits extract of bitter melon showed strong antioxidant and hypoglycemic activities in experimental condition both in vivo and in vitro. Recent scientific evaluation of this plant extracts also showed potential therapeutic benefit in diabetes and obesity related metabolic dysfunction in experimental animals and clinical studies. These beneficial effects are mediated probably by inducing lipid and fat metabolizing gene expression and increasing the function of AMPK and PPARs, and so forth. This review will thus focus on the recent findings on beneficial effect of Momordica charantia extracts on metabolic syndrome and discuss its potential mechanism of actions.

Protective effects of ginseng leaf extract using enzymatic extraction against oxidative damage of UVA-irradiated human keratinocytes

UVA is responsible for numerous biological effects on the skin, including premature aging characterized by wrinkles, leathery texture, and mottled pigmentation. The objective of this study was evaluating the protective effect of ginseng leaf extract prepared by Ultraflo L on skin from photodamage. Anti-wrinkle effect of ginseng leaf extract with or without Ultraflo L treatment were tested on human keratinocyte cells (HaCaT) irradiated with ultraviolet (UV) A. Ginseng leaves inhibited ROS generation, GHS depletion, and expression of MMP-2 and MMP-9 induced by UVA irradiation. The glutathione (GSH) content of the cells was significantly increased by over 25 μg mL(-1) of Ultraflo-treated extract (UTGL) as well as by over 100 μg mL(-1) of nonenzyme-treated extract (NEGL) compared to control. UTGL and NEGL treatments significantly decreased expression of metalloproteinase (MMP)-2 and 9 compared with control, but inhibitory effects of two groups on expression of MMPs were not significantly different. Overall, ULtraflo L-treated ginseng leaves inhibited ROS generation, GHS depletion, and expression of MMP-2 and MMP-9 in UVA photodamaged HaCat cells. From these results, enzyme-treated ginseng leaf extract has advantages over untreated ginseng leaves and have potential as a skin protective ingredient against UVA-induced photodamage.

Phytotherapy in diabetes: Review on potential mechanistic perspectives

Diabetes mellitus (DM) is a widely spread epidemic disease that results from the absence of insulin, decreased secretion and/or impaired function. Since DM is a multi-factorial disease, the available pharmaceuticals, despite their sensible treatment, target mostly one pathway to control hyperglycemia and encounter several side effects. Therefore, new therapeutic paradigms aim to hit several pathways using only one agent. Traditionally, antidiabetic plants and/or their active constituents may fulfill this need. More than 200 species of plants possess antidiabetic properties which were evaluated mostly by screening tests without digging far for the exact mode of action. Searching among the different literature resources and various database and in view of the above aspects, the present article provides a comprehensive review on the available antidiabetic plants that have been approved by pharmacological and clinical evaluations, and which their mechanism(s) of action is assured. These plants are categorized according to their proved mode of action and are classified into those that act by inhibiting glucose absorption from intestine, increasing insulin secretion from the pancreas, inhibiting glucose production from hepatocytes, or enhancing glucose uptake by adipose and muscle tissues. The current review also highlights those that mimic in their action the new peptide analogs, such as exenatide, liraglutide and dipeptidylpeptidase-4 inhibitors that increase glucagon-like peptide-1 serum concentration and slow down the gastric emptying.

Regulation effects of TZQ-F on adipocyte differentiation and insulin action

ETHNOPHARMACOLOGICAL RELEVANCE

TZQ has been used in traditional Chineses medicine for treating diabetes. Based on the recipe of traditional anti-diabetic formula TZQ, we have developed TZQ-F which has been in phase 2 clinical trails. To study the mechanisms by which TZQ-F ameliorates diabetes, we examined whether treatment with TZQ-F improves hyperinsulinemia, hyperglycemia and obesity in type 2 diabetic KKA(y) mice and whether this is associated with an improvement of adipocyte differentiation and insulin action.

METHODS

TZQ-F, fenofibrate, rosiglitazone or distilled water was administered to 7-week-old diabetic KKA(y) and nondiabetic C57BL/6J mice for 8 weeks. Insulin resistance index, body weight and levels of serum blood glucose, leptin, insulin and adiponectin were evaluated. The expression of peroxisome proliferator-activated receptor γ (PPARγ) in skeletal muscle and liver tissues were determined with real-time PCR and western boltting. The mRNA expressions of insulin receptor (InsR), insulin receptor substrate-1 (IRS-1), insulin receptor substrate-2 (IRS-2), glucose transporter-1 (Glut-1) and Phosphoenolpyruvate 3-kinases (PI3K) in skeletal muscle and liver tissues were determined with real-time PCR. Histopathology of liver has been observed.

RESULTS

Treatment of TZQ-F for 8 weeks ameliorated hyperglycemia, hyperinsulinemia, hyperleptinemia and hypoadiponectinemia in KKA(y) mice. TZQ-F also up-regulated expression of PPARγ in liver tissue. However, it had no effect on regulation of expression of PPARγ in muscle tissue. In addition, TZQ-F upregulates InsR, IRS-1, IRS-2, Glut-1, and PI3K mRNA expression. Consistent with the in vivo results, histology study demonstrated that TZQ-F alleviated pathologic changes of the liver induced by high-fat diet.

CONCLUSIONS

These results first indicate that TZQ-F can be beneficial for reducing hyperinsulinemia, hyperglycemia and obesity through its potency of regulating adipocyte differentiation and insulin action.

SDF7, a group of Scoparia dulcis Linn. derived flavonoid compounds, stimulates glucose uptake and regulates adipocytokines in 3T3-F442a adipocytes

ETHNOPHARMACOLOGY RELEVANCE

Adipocytes are major tissues involved in glucose uptake second to skeletal muscle and act as the main adipocytokines mediator that regulates glucose uptake mechanism and cellular differentiation. The objective of this study were to examine the effect of the SDF7, which is a fraction consists of four flavonoid compounds (quercetin: p-coumaric acid: luteolin: apigenin=8: 26: 1: 3) from Scoparia dulcis Linn., on stimulating the downstream components of insulin signalling and the adipocytokines expression on different cellular fractions of 3T3-F442a adipocytes.

MATERIAL AND METHODS

Morphology and lipid accumulation of differentiated 3T3-F442a adipocytes by 100 nM insulin treated with different concentrations of SDF7 and rosiglitazone were examined followed by the evaluation of glucose uptake activity expressions of insulin signalling downstream components (IRS-1, PI3-kinase, PKB, PKC, TC10 and GLUT4) from four cellular fractions (plasma membrane, cytosol, high density microsome and low density microsome). Next, the expression level of adipocytokines (TNF-α, adiponectin and leptin) and immunoblotting of treated 3T3-F442 adipocytes was determined at 30 min and 480 min. Glucose transporter 4 (GLUT4) translocation of 3T3-F442a adipocytes membrane was also determined. Lastly, mRNA expression of adiponectin and PPAR-γ of 3T3-F442a adipocytes were induced and compared with basal concentration.

RESULTS

It was found that SDF7 was able to induce adipocytes differentiation with great extends of morphological changes, lipid synthesis and lipid stimulation in vitro. SDF7 stimulation of glucose transport on 3T3-F442a adipocytes are found to be dose independent, time-dependent and plasma membrane GLUT4 expression-dependent. Moreover, SDF7 are observed to be able to suppress TNF-α and leptin expressions that were mediated by 3T3-F442a adipocytes, while stimulated adiponectin secretion on the cells. There was a significant expression (p<0.01) of protein kinase C and small G protein TC10 on 3T3-F442a adipocytes upon treatment with SDF7 as compared to the control. SDF7 was also found to be effective in stimulating adiponectin and PPAR-γ mRNA upregulation at 50 µg/ml.

CONCLUSION

SDF7 exhibited good lipogenesis, adiponectinesis and glucose uptake stimulatory properties on 3T3-F442a adipocytes.

Momordica charantia and its novel polypeptide regulate glucose homeostasis in mice via binding to insulin receptor

Momordica charantia (MC) has been used as an alternative therapy for diabetes mellitus. This study analyzed and elucidated therapeutic targets contributing to the hypoglycemic effect of aqueous extract of MC seeds (MCSE) by transcriptomic analysis. Protein ingredients aimed at the hypoglycemic target were further identified by proteomic, docking, and receptor-binding assays. The data showed that MSCE (1 g/kg) significantly lowered the blood glucose level in normal and diabetic mice. Moreover, MCSE primarily regulated the insulin signaling pathway in muscles and adipose tissues, suggesting that MCSE might target insulin receptor (IR), stimulate the IR-downstream pathway, and subsequently display hypoglycemic activity in mice. It was further revealed that inhibitor against trypsin (TI) of MC directly docked into IR and activated the kinase activity of IR in a dose-dependent manner. In conclusion, the findings suggested that MCSE regulated glucose metabolism mainly via the insulin signaling pathway. Moreover, TI was newly identified as a novel IR-binding protein of MC that triggered the insulin signaling pathway via binding to IR.

Safety evaluation of main alkaloids from Rhizoma Coptidis

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizoma Coptidis (RC), a widely used traditional Chinese medicine, has been used for the treatment of heat-clearing and detoxifying, but there is very little information on its safety.

AIM OF THE STUDY

To provide information on the safety of RC, we evaluated the toxicity of the crude RC and RC alkaloids (berberine, coptisine, palmatine and epiberberine) including cytotoxicity, acute toxicity in mice and sub-chronic toxicity in rats.

MATERIALS AND METHODS

The cytotoxicity of RC alkaloids was tested in HepG2 and 3T3-L1 cells by the MTT assay. The acute toxicity of RC alkaloids was tested in mice and the mortality was calculated at the end of experiment. For sub-chronic toxicity study, the rats were treated with the RC alkaloids at a dose of 156 mg/kg/day and RC at a dose of 521 mg/kg/day for 90 days. Mortality, clinical signs, body weight changes, organ weights, urinalysis and hematological parameters, gross necropsy and histopathology were monitored during the study period.

RESULTS

The cell assay indicates that the IC(50) values of berberine, coptisine, palmatine and epiberberine in HepG2 cells were 48.17, 64.81, 112.80 and 120.58 μg/mL, which in 3T3-L1 cells were 41.76, 56.48, 84.32 and 104.18 μg/mL, respectively. In the acute toxicity assay, the LD(50) values of four alkaloids were 713.57, 852.12, 1533.68 and 1360 mg/kg, respectively. However, in the sub-chronic toxicity study, no mortality and morbidity were observed which could be related to RC alkaloids and RC treatment. Besides, there was no abnormality in clinical signs, body weights, organ weights, urinalysis, hematological parameters, gross necropsy and histopathology in any of the animals after the oral administration of RC alkaloids and RC.

CONCLUSIONS

Taking these results together, we came to the conclusion that the toxicity of berberine is the maximum and palmatine is the minimal in four RC alkaloids. The currently recommended doses of RC alkaloids and RC consumed are relatively safe.

Ficus deltoidea: A Potential Alternative Medicine for Diabetes Mellitus

Ficus deltoidea from the Moraceae family has been scientifically proven to reduce hyperglycemia at different prandial states. In this study, we evaluate the mechanisms that underlie antihyperglycemic action of Ficus deltoidea. The results had shown that hot aqueous extract of Ficus deltoidea stimulated insulin secretion significantly with the highest magnitude of stimulation was 7.31-fold (P < 0.001). The insulin secretory actions of the hot aqueous extract involved K⁺  _ATP channel-dependent and K⁺  _ATP-channel-independent pathway. The extract also has the ability to induce the usage of intracellular Ca²⁺ to trigger insulin release. The ethanolic and methanolic extracts enhanced basal and insulin-mediated glucose uptake into adipocytes cells. The extracts possess either insulin-mimetic or insulin-sensitizing property or combination of both properties during enhancing glucose uptake into such cells. Meanwhile, the hot aqueous and methanolic extracts augmented basal and insulin-stimulated adiponectin secretion from adipocytes cells. From this study, it is suggested that Ficus deltoidea has the potential to be developed as future oral antidiabetic agent.

Antidiabetic potentials of Momordica charantia: multiple mechanisms behind the effects

Momordica charantia fruits are used as a vegetable in many countries. From time immemorial, it has also been used for management of diabetes in the Ayurvedic and Chinese systems of medicine. Information regarding the standardization of this vegetable for its usage as an antidiabetic drug is scanty. There are many reports on its effects on glucose and lipid levels in diabetic animals and some in clinical trials. Reports regarding its mechanism of action are limited. So in the present review all the information is considered to produce some concrete findings on the mechanism behind its hypoglycemic and hypolipidemic effects. Studies have shown that M. charantia repairs damaged β-cells, increases insulin levels, and also enhance the sensitivity of insulin. It inhibits the absorption of glucose by inhibiting glucosidase and also suppresses the activity of disaccharidases in the intestine. It stimulates the synthesis and release of thyroid hormones and adiponectin and enhances the activity of AMP-activated protein kinase (AMPK). Effects of M. charantia like transport of glucose in the cells, transport of fatty acids in the mitochondria, modulation of insulin secretion, and elevation of levels of uncoupling proteins in adipose and skeletal muscles are similar to those of AMPK and thyroxine. Therefore it is proposed that effects of M. charantia on carbohydrate and fat metabolism are through thyroxine and AMPK.

Preventive effects of chebulic acid isolated from Terminalia chebula on advanced glycation endproduct-induced endothelial cell dysfunction

AIM OF THE STUDY

The aqueous extract of Terminalia chebular fruits was reported to have anti-hyperglycemia and anti-diabetic complication effects. The present study therefore investigated the protective mechanism of chebulic acid, a phenolcarboxylic acid compound isolated from the ripe fruits of Terminalia chebula against advanced glycation endproducts (AGEs)-induced endothelial cell dysfunction.

MATERIALS AND METHODS

To investigate the protective mechanism of chebulic acid against vascular endothelial dysfunction human umbilical vein endothelial cells (HUVEC) were treated with chebulic acid in the presence/absence of glyceraldehyde-related AGEs (glycer-AGEs).

RESULTS

HUVEC incubated with 100 μg/ml of glycer-AGEs had significantly enhanced reactive oxygen species formation, whereas the treatment of chebulic acid dose-dependently reduced glycer-AGE-induced formation to 108.2 ± 1.9% for 25 μM versus 137.8 ± 1.1% for glycer-AGEs treated alone. The transendothelial electrical resistance (TER) value of the glycer-AGEs group was dramatically decreased to 76.9 ± 2.2% compared to the control, whereas chebulic acid treatment prevented glycer-AGE-induced TER change with a value of 91.3 ± 5.3%. The incubation of confluent HUVEC with 100 μg/ml of glycer-AGEs for 24h remarkably increased the adhesion of human monocytic THP-1 cells compared to non-stimulated HUVEC. These increases in HUVEC adhesiveness were dose-dependently reduced by chebulic acid.

CONCLUSIONS

The present study shows the effects of chebulic acid against the progression of AGE-induced endothelial cell dysfunction suggesting that this compound may constitute a promising intervention agent against diabetic vascular complications.

Antidiabetic effects of bitter gourd extracts in insulin-resistant db/db mice

Bitter gourd (BG, Momordica charantia) exerts proven blood glucose- and body weight-lowering effects. To develop an effective and safe application, it is necessary to identify the bioactive compounds and biochemical mechanisms responsible for these effects in type 2 diabetes. A total of forty-five 4-week-old male db/db mice were assigned to five groups of nine each. The mice were given sterile tap water as a control, a whole fruit powder, the lipid fraction, the saponin fraction or the hydrophilic residue of BG at a daily oral dosage of 150 mg/kg body weight for 5 weeks, respectively. Weight gain was significantly decreased in all the BG-treated groups (P ≤ 0.05). Glycated Hb levels were the highest in the control mice compared with all the four BG-treated mice (P = 0.02). The lipid fraction had the strongest effect, and it tended (P = 0.075) to reduce glycated Hb levels from 9.3 % (control mice) to 8.0 % (lipid fraction-treated mice). The lipid and saponin fractions reduced lipid peroxidation of adipose tissue significantly (P ≤ 0.01). Additionally, the saponin fraction and the lipid fraction reduced protein tyrosine phosphatase 1B (PTP 1B) activity in skeletal muscle cytosol by 25 % (P = 0.05) and 23 % (P = 0.07), respectively. PTP 1B is the physiological antagonist of the insulin signalling pathway. Inhibition of PTP 1B increases insulin sensitivity. This is the first study to demonstrate that BG is involved in PTP 1B regulation, and thus explains one possible biochemical mechanism underlying the antidiabetic effects of BG in insulin resistance and type 2 diabetes.

Momordica charantia (bitter melon) inhibits primary human adipocyte differentiation by modulating adipogenic genes

BACKGROUND

Escalating trends of obesity and associated type 2 diabetes (T2D) has prompted an increase in the use of alternative and complementary functional foods. Momordica charantia or bitter melon (BM) that is traditionally used to treat diabetes and complications has been demonstrated to alleviate hyperglycemia as well as reduce adiposity in rodents. However, its effects on human adipocytes remain unknown. The objective of our study was to investigate the effects of BM juice (BMJ) on lipid accumulation and adipocyte differentiation transcription factors in primary human differentiating preadipocytes and adipocytes.

METHODS

Commercially available cryopreserved primary human preadipocytes were treated with and without BMJ during and after differentiation. Cytotoxicity, lipid accumulation, and adipogenic genes mRNA expression was measured by commercial enzymatic assay kits and semi-quantitative RT-PCR (RT-PCR).

RESULTS

Preadipocytes treated with varying concentrations of BMJ during differentiation demonstrated significant reduction in lipid content with a concomitant reduction in mRNA expression of adipocyte transcription factors such as, peroxisome proliferator-associated receptor gamma (PPARgamma) and sterol regulatory element-binding protein 1c (SREBP-1c) and adipocytokine, resistin. Similarly, adipocytes treated with BMJ for 48 h demonstrated reduced lipid content, perilipin mRNA expression, and increased lipolysis as measured by the release of glycerol.

CONCLUSION

Our data suggests that BMJ is a potent inhibitor of lipogenesis and stimulator of lipolysis activity in human adipocytes. BMJ may therefore prove to be an effective complementary or alternative therapy to reduce adipogenesis in humans.

Impact of dietary polyphenols on carbohydrate metabolism

Polyphenols, including flavonoids, phenolic acids, proanthocyanidins and resveratrol, are a large and heterogeneous group of phytochemicals in plant-based foods, such as tea, coffee, wine, cocoa, cereal grains, soy, fruits and berries. Growing evidence indicates that various dietary polyphenols may influence carbohydrate metabolism at many levels. In animal models and a limited number of human studies carried out so far, polyphenols and foods or beverages rich in polyphenols have attenuated postprandial glycemic responses and fasting hyperglycemia, and improved acute insulin secretion and insulin sensitivity. The possible mechanisms include inhibition of carbohydrate digestion and glucose absorption in the intestine, stimulation of insulin secretion from the pancreatic β–cells, modulation of glucose release from the liver, activation of insulin receptors and glucose uptake in the insulin-sensitive tissues, and modulation of intracellular signalling pathways and gene expression. The positive effects of polyphenols on glucose homeostasis observed in a large number of in vitro and animal models are supported by epidemiological evidence on polyphenol-rich diets. To confirm the implications of polyphenol consumption for prevention of insulin resistance, metabolic syndrome and eventually type 2 diabetes, human trials with well-defined diets, controlled study designs and clinically relevant end-points together with holistic approaches e.g., systems biology profiling technologies are needed.

Science Across Borders: 5th Annual Natural Health Product Research Conference—March 26–29, 2008, Toronto, Canada

Canada is experiencing a growing interest in the use of alternative therapies and products particularly natural health products (NHP). In 1997, Canadians spent around C$ 2 billion on NHP. In an attempt to catch with this popularity of NHP use, Canadian researchers and administrators from academia, industry and government jointly established the Natural Health Product Research Society of Canada (NHPRS). Since its formation, NHPRS has been organizing an annual meeting which brings together world renowned researchers and experts in the area of NHP research. For 2008, the annual NHPRS meeting took place in Toronto from the 26th to 29th of March with a focus on ‘Science Across Borders: Global Natural Health Products Research’. The scientific program was spread into three days of plenary lectures and oral presentations. The different sessions containing these talks were on: ethnobotany around the world; chemical analysis of NHP; product standards and quality control; ethnomedicine; novel analytical approaches; systemic research, nutrisciences and molecular medicine; and drug development from NHP. The meeting proved to be a great success in terms of the speakers that were invited and based on the data that was presented which highlighted recent research taking place in the field of NHP not only in Canada but from many parts of the world.

Fruit extracts of Momordica charantia potentiate glucose uptake and up-regulate Glut-4, PPAR gamma and PI3K

ETHNOPHARMACOLOGICAL RELEVANCE

Momordica charantia fruit is a widely used traditional medicinal herb as, anti-diabetic, anti-HIV, anti-ulcer, anti-inflammatory, anti-leukemic, anti-microbial, and anti-tumor.

AIMS OF STUDY

The present study is undertaken to investigate the possible mode of action of fruit extracts derived from Momordica charantia (MC) and study its pharmacological effects for controlling diabetic mellitus. Effects of aqueous and chloroform extracts of Momordica charantia fruit on glucose uptake and up-regulation of glucose transporter (Glut-4), peroxisome proliferator activator receptor gamma (PPAR gamma) and phosphatidylinositol-3 kinase (PI3K), were investigated to show its efficacy as a hypoglycaemic agent.

MATERIALS AND METHODS

Dose dependent glucose uptake assay was performed on L6 myotubes using 2-deoxy-D-[1-(3)H] glucose. Up-regulatory effects of the extracts on the mRNA expression level of Glut-4, PPAR gamma and PI3K have been studied.

RESULTS

The association of Momordica charantia with the aqueous and chloroform extracts of Momordica charantia fruit at 6 microg/ml has shown significant up-regulatory effect, respectively, by 3.6-, 2.8- and 3.8-fold on the battery of targets Glut-4, PPAR gamma and PI3K involved in glucose transport. The up-regulation of glucose uptake was comparable with insulin and rosiglitazone which was approximately 2-fold over the control. Moreover, the inhibitory effect of the cyclohexamide on Momordica charantia fruit extract mediated glucose uptake suggested the requirement of new protein synthesis for the enhanced glucose uptake.

CONCLUSION

This study demonstrated the significance of Glut-4, PPAR gamma and PI3K up-regulation by Momordica charantia in augmenting the glucose uptake and homeostasis.

Cecropia obtusifolia Bertol and its active compound, chlorogenic acid, stimulate 2-NBDglucose uptake in both insulin-sensitive and insulin-resistant 3T3 adipocytes

ETHNOPHARMACOLOGICAL IMPORTANCE

Cecropia obtusifolia Bertol (Cecropiaceae) is a plant extensively used for the empirical treatment of type 2 diabetes in México. Although some of its hypoglycemic principles have been described, their mechanisms of action remain unclear.

AIM OF THE STUDY

To investigate the anti-diabetic mechanisms of Cecropia obtusifolia aqueous extract (CAE) and its active compound chlorogenic acid (CGA).

MATERIALS AND METHODS

Non-toxic concentrations of CAE and CGA were assayed on the adipogenesis and 2-NBDglucose uptake in 3T3-F442A murine adipocytes.

RESULTS

Added to adipogenic medium, CAE 70 microg/ml induced a modest increment (20%) in 3T3 adipogenesis whereas CGA did not affect adipogenesis at any of the tested concentrations (0.1-100 microM). Both preparations stimulated 2-NBDG uptake in adipocytes by 51% (CAE) and 176% (CGA) in the absence of insulin, and by 174% (CAE) and 404% (CGA) in the presence of the hormone. CAE and CGA also stimulated the 2-NBDG uptake in insulin-resistant 3T3 adipocytes by 35% and 141%, respectively, compared with the incorporation shown by insulin-sensitive adipocytes stimulated by the hormone. The potency of CGA to stimulate 2-NBDG uptake was comparable to the anti-diabetic drug rosiglitazone.

CONCLUSION

Cecropia obtusifolia and CGA exert their anti-diabetic effects stimulating glucose uptake in both insulin-sensitive and insulin-resistant adipocytes without appreciable pro-adipogenic effects.

Bitter gourd (Momordica charantia) improves insulin sensitivity by increasing skeletal muscle insulin-stimulated IRS-1 tyrosine phosphorylation in high-fat-fed rats

The aim of this present study was to investigate the effect of bitter gourd extract on insulin sensitivity and proximal insulin signalling pathways in high-fat-fed rats. High-fat feeding of male Wistar rats for 10 weeks decreased the glucose tolerance and insulin sensitivity compared to chow-fed control rats. Bitter gourd extract supplementation for 2 weeks (9th and 10th) of high-fat feeding improved the glucose tolerance and insulin sensitivity. In addition bitter gourd extract reduced the fasting insulin (43 (se4·4)v. 23 (se5·2) μU/ml,P < 0·05), TAG (134 (se12)v. 96 (se5·5) mg/dl,P < 0·05), cholesterol (97 (se6·3)v. 72 (se5·2) mg/dl,P < 0·05) and epidydimal fat (4·8 (se0·29)v. 3·6 (se0·24) g,P < 0·05), which were increased by high-fat diet (HFD). High-fat feeding and bitter gourd supplementation did not have any effect on skeletal muscle insulin receptor, insulin receptor subtrate-1 (IRS-1) and insulin- stimulated insulin receptor tyrosine phosphorylation compared to chow-fed control rats. However high-fat feeding for 10 weeks reduced the insulin-stimulated IRS-1 tyrosine phosphorylation compared to control rats. Bitter gourd supplementation together with HFD for 2 weeks improved the insulin-stimulated IRS-1 tyrosine phosphorylation compared to rats fed with HFD alone. Our results show that bitter gourd extract improves insulin sensitivity, glucose tolerance and insulin signalling in HFD-induced insulin resistance. Identification of potential mechanism(s) by which bitter gourd improves insulin sensitivity and insulin signalling in high-fat-fed rats may open new therapeutic targets for the treatment of obesity/dyslipidemia-induced insulin resistance.