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

Assessing the potential fasting and postprandial mechanisms involved in the acute hypoglycemic and anti-hyperglycemic effects of four selected plants from Iran used in traditional Persian medicine

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Persian medicine (TPM), people often use herbal infusions as a dosage form to treat diseases related to hyperglycemia, known as 'dam-kardeh'. Traditionally, herbal preparations of Eryngium bungei Boiss. (E. b), Tragopogon buphthalmoides (DC.) Boiss. (T. b), Salvia hydrangea DC. ex Benth. (S. h), and Juniperus polycarpos K. Koch. (J. p) are used to manage diabetes in Iran. However, there is no evidence of their effectiveness in controlling glucose levels and their mechanisms remain unclear.

AIM OF THE STUDY

This study aimed to investigate whether traditional doses of plant infusions can have hypoglycemic and/or anti-hyperglycemic effects during fasting and/or postprandial states and establish the basis for future research on their potential mechanisms of action.

MATERIALS AND METHODS

The effects of traditional doses of herbal extracts on blood glucose levels in STZ-NA-induced hyperglycemic rats were investigated in 2-h acute tests during fasting and postprandial states (with a glucose load). In addition, the potential inhibitory effect in vitro of enzymes involved in relevant pathways, such as gluconeogenesis (fructose-1,6-bisphosphatase, FBPase and glucose-6-phosphatase, G6Pase), carbohydrate breakdown (intestinal α-glucosidases), and insulin sensitivity (protein tyrosine phosphatase 1B, PTP-1B) was evaluated. Acute toxicity tests were carried out and HPLC-SQ-TOF was used to analyze the chemical profiles of the plant extracts.

RESULTS

In the fasting state, T. b, S. h, and E. b were as effective as glibenclamide in lowering blood glucose levels in hyperglycemic rats. Moreover, all three suppressed G6Pase and FBPase enzymatic activity by 90-97% and 80-91%, respectively. On the other hand, significant postprandial hypoglycemic efficacy was observed for E. b, S. h, and T. b. Based on the AUC values, T. b caused a reduction comparable to the therapeutic efficacy of repaglinide. When investigating the possible mechanisms of action involved in this activity, E. b, S. h, and T. b showed significant inhibition of PTP-1B in vitro (>70%). Finally, all plant extracts showed no signs of acute toxicity. Several compounds that may contribute to biological activities were identified, including phenolic acids and flavonoid glycosides.

CONCLUSIONS

The present study supports the traditional use of T. b, E. b and S. h for the control of diabetes in the fasting and postprandial state. Moreover, these plants were found to be rich in bioactive compounds with hypoglycemic and antihyperglycemic activities. On the other hand, J. p, showed a modest effect only in the fasting state and after 90 min. Further studies are needed to expand these results by analyzing the chemical composition and using complementary experimental models.

Altered Igf2 imprint leads to accelerated adipogenesis and early onset of metabolic syndrome in male mice following gestational arsenic exposure

Developmental exposure to environmental pollutants has been shown to promote adverse health outcomes in offspring. Exposure to heavy metals such as arsenic which also has endocrine-disrupting activity is being increasingly linked with cancers, diabetes, and lately with Metabolic Syndrome (MetS). In this work, we have assessed the effects of preconceptional plus gestational arsenic exposure on the developmental programming of MetS in offspring. In our study, only gestational arsenic exposure led to reduced birth weight, followed by catch-up growth, adiposity, elevated serum triglycerides levels, and hyperglycemia in male offspring. Significant adipocyte dysfunction was observed in offspring with increased hypertrophy, insulin resistance, and chronic inflammation in epididymal white adipose tissue. Adipose tissue regulates the metabolic health of individuals and its dysfunction resulted in elevated serum levels of metabolism-regulating adipokines (Leptin, Resistin) and pro-inflammatory cytokines (PAI-1, TNFα). The progenitor adipose-derived stem cells (AdSCs) from exposed progeny had increased proliferation and adipogenic potential with excess lipid accumulation. We also found increased activation of Akt, ERK1/2 & p38 MAPK molecules in arsenic-exposed AdSCs along with increased levels of phospho-Insulin-like growth factor-1 receptor (p-IGF1R) and its upstream activator Insulin-like growth factor-2 (IGF2). Overexpression of Igf2 was found to be due to arsenic-mediated DNA hypermethylation at the imprinting control region (ICR) located -2kb to -4.4 kb upstream of the H19 gene which caused a reduction in the conserved zinc finger protein (CTCF) occupancy. This further led to persistent activation of the MAPK signaling cascade and enhanced adipogenesis leading to the early onset of MetS in the offspring.

Improving the Effect of Ferulic Acid on Inflammation and Insulin Resistance by Regulating the JNK/ERK and NF-κB Pathways in TNF-α-Treated 3T3-L1 Adipocytes

In this study, ferulic acid was investigated for its potential in suppressing TNF-α-treated inflammation and insulin resistance in adipocytes. Ferulic acid suppressed TNF-α, IL-6, IL-1β, and MCP-1. TNF-α increased p-JNK and ERK1/2, but treatment with ferulic acid (1, 10, and 50 μM) decreased p-JNK and ERK1/2. TNF-α induced the activation of IKK, IκBα, and NF-κB p65 compared to the control, but ferulic acid inhibited the activation of IKK, IκBα, and NF-κB p65. Following treatment with TNF-α, pIRS-1ser307 increased and pIRS-1tyr612 decreased compared to the control. Conversely, as a result of treatment with 1, 10, and 50 μM ferulic acid, pIRS-1ser307 was suppressed, and pIRS-1tyr612 was increased. Therefore, ferulic acid reduced inflammatory cytokine secretion by regulating JNK, ERK, and NF-κB and improved insulin resistance by suppressing pIRS-1ser. These findings indicate that ferulic acid can improve inflammation and insulin resistance in adipocytes.

In Silico Studies of Four Compounds of Cecropia obtusifolia against Malaria Parasite

Malaria is a disease that affects many people in the world. In Mexico, malaria remains an active disease in certain regions, particularly in the states of Chiapas and Chihuahua. While antimalarial effects have been attributed to some species of Cecropia in various countries, no such studies have been conducted in Mexico. Therefore, the objective of this study was to evaluate the in silico antimalarial activity of some active compounds identified according to the literature in the species of Cecropia obtusifolia, belonging to the Cecropiaceae family, such as ursolic acid, α-amyrin, chrysin, and isoorientin. These compounds were evaluated with specific molecular docking and molecular dynamics (MD) studies using three different malarial targets with the PDB codes 1CET, 2BL9, and 4ZL4 as well as the prediction of their pharmacokinetic (Pk) properties. Docking analysis revealed the following best binding energies (kcal/mol): isoorientin-1CET (-9.1), isoorientin-2BL9 (-8.8), and chrysin-4ZL4 (-9.6). MD simulation validated the stability of the complexes. Pharmacokinetics analysis suggested that the compounds would generally perform well if administered. Therefore, these results suggest that these compounds may be used as potential drugs for the treatment of malaria.

Potential use of the Asteraceae family as a cure for diabetes: A review of ethnopharmacology to modern day drug and nutraceuticals developments

The diabetes-associated mortality rate is increasing annually, along with the severity of its accompanying disorders that impair human health. Worldwide, several medicinal plants are frequently urged for the management of diabetes. Reports are available on the use of medicinal plants by traditional healers for their blood-sugar-lowering effects, along with scientific evidence to support such claims. The Asteraceae family is one of the most diverse flowering plants, with about 1,690 genera and 32,000 species. Since ancient times, people have consumed various herbs of the Asteraceae family as food and employed them as medicine. Despite the wide variety of members within the family, most of them are rich in naturally occurring polysaccharides that possess potent prebiotic effects, which trigger their use as potential nutraceuticals. This review provides detailed information on the reported Asteraceae plants traditionally used as antidiabetic agents, with a major focus on the plants of this family that are known to exert antioxidant, hepatoprotective, vasodilation, and wound healing effects, which further action for the prevention of major diseases like cardiovascular disease (CVD), liver cirrhosis, and diabetes mellitus (DM). Moreover, this review highlights the potential of Asteraceae plants to counteract diabetic conditions when used as food and nutraceuticals. The information documented in this review article can serve as a pioneer for developing research initiatives directed at the exploration of Asteraceae and, at the forefront, the development of a botanical drug for the treatment of DM.

The effect of Urtica dioica extract on oxidative stress, heat shock proteins, and brain histopathology in multiple sclerosis model

Multiple sclerosis (MS) results from the destruction of myelin and focal inflammation. The study aimed to evaluate the effect of hydroalcoholic extract of Urtica dioica on oxidative stress, heat shock proteins, and brain histopathology in multiple sclerosis model. Sixty male C57BL/6 mice were divided into six groups of 10. Groups included positive control, negative control, and treatment groups with U. dioica extract at a dose of 50, 100, 200, and 400 mg/kg for 21 days (three times a week). The MS model was developed by a diet containing 0.2% cuprizone for 6 weeks. A section of brains was evaluated with Luxol Fast Blue staining and the other part evaluated with heat shock protein (HSP) kits 60 and 70, total antioxidant capacity (TAC), and malondialdehyde (MDA). In sections of corpus callosum, the highest amount of myelin was observed in the negative controls, while the use of cuprizone in the positive controls caused the destruction and reduction of myelin. The use of U. dioica extract in therapeutic groups except at a dose of 50 mg/kg could reduce myelin degradation to some extent and lead to remyelination. However, myelin levels in treatment groups were not significantly different from any of the negative and positive controls. Although HSP60 decreased in the treatment groups, there was no significant difference between the positive and negative controls. Treatment with this extract significantly reduced the amount of HSP70 compared with the positive controls. The decreased TAC and increased MDA in positive controls indicated oxidative stress, respectively. Furthermore, the extract led to an increase and decrease of TAC and MDA in the treatment groups, respectively. However, only the MDA level was significantly different from that of the positive controls. Therefore, the antioxidant effects of U. dioica extract could decrease cuprizone-induced oxidative stress and be effective in improving demyelination.

Phenolic compounds as antidiabetic, anti-inflammatory, and anticancer agents and improvement of their bioavailability by liposomes

Phenolic compounds, widespread in plants, are a necessary part of the human regimen due to their antioxidant and pro-oxidative properties. Naturally, phenolics structurally range from a very simple phenolic molecule moiety to an intricate polymer. For decades, phenolic compounds have gained pronounced attention because of their protective effects against degenerative disorders such as inflammation, diabetes and cancer. Physico-chemical properties (eg, solubility) restricted their bioactivity and also limited their usage as nutraceutical ingredients. However, encapsulation technology like liposomal formulations has been developed for the delivery of phenolic compounds without affecting their original aesthetic and organoleptic property. Hence, this review outlines the antioxidant and pro-oxidative properties of phenolic compounds and focuses on biological activity reports of flavonoids and phenolic acids as antidiabetic, anti-inflammatory and anticancer agents. Also, the delivery applications of phenolic compounds as liposomes are discussed with few examples.

Controlled Release of Chlorogenic Acid from Polyvinyl Alcohol/Poly(γ-Glutamic Acid) Blended Electrospun Nanofiber Mats with Potential Applications in Diabetic Foot Treatment

This work biosynthesized poly(γ-glutamic acid) (γ-PGA) produced by Bacillus licheniformis ATCC-9945a. This material was utilized to prepare electrospun nanofibers with solutions of 10% polyvinyl alcohol (PVA) (w/v) mixed with γ-PGA at 5 and 10% w/v, intended as a wound dressing for diabetic foot treatment. These solutions were loaded with chlorogenic acid (CGA), an active hypoglycemic agent. Morphological analysis showed a decrease in size of the fibers with the combination of PVA/γ-PGA compared to pure PVA nanofibers, which was attributed to the hydrogen bonding interactions between the glutaraldehyde vapors, γ-PGA, and PVA that permitted nanofiber cross-linking and allowed CGA release. The in vitro release analysis showed that the PVA membranes reached 28% delivery after the first 24 h. Notably, the nanofiber mat with PVA blended with 5% γ-PGA reached 57% delivery, and the PVA nanofiber with 10% γ-PGA reached 66% release after the same amount of time. The rate constant for the release kinetics showed that PVA with 5% γ-PGA had a higher value than that of the other samples, reaching saturation first.

Pharmacognostic Evaluation of Ten Species of Medicinal Importance of Cecropia: Current Knowledge and Therapeutic Perspectives

This work covers a systematic review of literature about the genus Cecropia from 1978 to 2020, emphasizing the analysis of 10 of the most relevant species and their associated biological activities. Cecropia is a neotropical genus, which comprises about 61 native species in the American continent where it is known to be part of the traditional medicine of numerous countries. Secondary metabolites described for this genus showed an elevated structural and functional diversity, where polyphenols have been the most abundant. Based on this diversity, Cecropia phytochemicals represent an important source of potential therapeutic agents yet to be exploited. This review also highlights the effectiveness of combining chemometrics and ultra-performance liquid chromatography-tandem mass spectrometry as a novel approach to successfully single out Cecropia species phytochemicals. While the medicinal use of Cecropia species is officially recognized in National Pharmacopoeias and Formularies of several Latin American countries, it is important to recognize that these phytomedicines are complex mixtures requiring a thorough understanding of their chemical composition and their correlation with biological activities to guarantee their quality, safety, and efficacy.

Antidiabetic Flavonoids from Fruits of Morus alba Promoting Insulin-Stimulated Glucose Uptake via Akt and AMP-Activated Protein Kinase Activation in 3T3-L1 Adipocytes

Morus alba (Moraceae), known as white mulberry, has been used to treat fever, protect against liver damage, improve eyesight, and lower blood sugar levels in traditional oriental medicine. Few studies have been conducted on the antidiabetic compounds identified from M. alba and their underlying mechanisms of action. Consequently, in this study, the fruits of M. alba were investigated for potential antidiabetic natural products using 3T3-L1 adipocytes. Phytochemical analysis of the ethanolic extract of M. alba fruits, followed by high-performance liquid chromatography (HPLC), purification led to the isolation of two main compounds: rutin and quercetin-3-O-β-d-glucoside (Q3G). Long-term use of available drugs for treating type 2 diabetes ((T2D) is often accompanied by undesirable side effects, which have generated increased interest in the development of more effective and safer antidiabetic agents. Examination of the isolated compounds, rutin and Q3G, for antidiabetic or anti-obesity properties or both in 3T3-L1 adipocytes demonstrated that they both improved glucose uptake via Akt-mediated insulin signaling pathway or AMP-activated protein kinase (AMPK) activation in 3T3-L1 adipocytes. The compounds also showed a positive effect on lipid accumulation in adipocytes, suggesting that glucose uptake occurred through activation of the Akt and AMPK signaling pathway without inducing adipogenesis. Taken together, our findings suggest that rutin and Q3G in M. alba fruits have the potential to induce fewer side effects such as weight gain, and these active compounds could be potential therapeutic candidates for the management of T2D.

Molecular mechanism of down-regulating adipogenic transcription factors in 3T3-L1 adipocyte cells by bioactive anti-adipogenic compounds

Obesity is growing at an alarming rate, which is characterized by increased adipose tissue. It increases the probability of many health complications, such as diabetes, arthritis, cardiac disease, and cancer. In modern society, with a growing population of obese patients, several individuals have increased insulin resistance. Herbal medicines are known as the oldest method of health care treatment for obesity-related secondary health issues. Several traditional medicinal plants and their effective phytoconstituents have shown anti-diabetic and anti-adipogenic activity. Adipose tissue is a major site for lipid accumulation as well as the whole-body insulin sensitivity region. 3T3-L1 cell line model can achieve adipogenesis. Adipocyte characteristics features such as expression of adipocyte markers and aggregation of lipids are chemically induced in the 3T3-L1 fibroblast cell line. Differentiation of 3T3-L1 is an efficient and convenient way to obtain adipocyte like cells in experimental studies. Peroxisome proliferation activated receptor γ (PPARγ) and Cytosine-Cytosine-Adenosine-Adenosine-Thymidine/Enhancer-binding protein α (CCAAT/Enhancer-binding protein α or C/EBPα) are considered to be regulating adipogenesis at the early stage, while adiponectin and fatty acid synthase (FAS) is responsible for the mature adipocyte formation. Excess accumulation of these adipose tissues and lipids leads to obesity. Thus, investigating adipose tissue development and the underlying molecular mechanism is important in the therapeutical approach. This review describes the cellular mechanism of 3T3-L1 fibroblast cells on potential anti-adipogenic herbal bioactive compounds.

Hypoglycemic effect and bioactive compounds associated with the ripening stages of the Cucurbita ficifolia Bouché fruit

BACKGROUND

The fruit of Cucurbita ficifolia Bouché is known in Mexico as 'chilacayote'. The scientific interest that C. ficifolia Bouché has acquired is due to its important hypoglycemic effect. The present research aimed (i) to discover whether this hypoglycemic property is present at different stages of development of this fruit, and (ii) to characterize some bioactive compounds with antioxidant or anti-inflammatory properties. Ethylene production, respiration rate, and maturity indices were determined during fruit development. The chemical characterization of the aqueous extracts of each stage of maturity studied was determined and their hypoglycemic effects were bioassayed using groups of normal mice with diabetes induced by streptozotocin at a dose of 500 mg^-1 kg^-1 body weight.

RESULTS

Respiration rate and ethylene production showed a typical pattern for non-climacteric fruit and the quality parameters did not show significant changes. Phenolic compounds such as gallic acid and chlorogenic acid were found to have the highest concentration at 15 days of development. Extracts at 15 days showed a hypoglycemic effect that was 11% greater than that of glibenclamide in diabetized mice.

CONCLUSION

All stages of development of C. ficifolia fruit had a hypoglycemic effect; however, the aqueous extract from the fruit at 15 days of development showed a better effect than glibenclamide. This finding highlights the potential of this maturity stage, and shows that it is appropriate for inclusion in treatments of type 2 diabetes mellitus. The results also indicate that phenolic compounds are mainly responsible for this effect and not d-chiro-inositol as previously thought. © 2020 Society of Chemical Industry.

Molecules Isolated from Mexican Hypoglycemic Plants: A Review

Like in many developing countries, in Mexico, the use of medicinal plants is a common practice. Based on our own field experience, there are at least 800 plants used for treating diabetes nowadays. Thus, their investigation is essential. In this context, this work aims to provide a comprehensive and critical review of the molecules isolated from Mexican hypoglycemic plants, including their source and target tested. In the last few years, some researchers have focused on the study of Mexican hypoglycemic plants. Most works describe the hypoglycemic effect or the mechanism of action of the whole extract, as well as the phytochemical profile of the tested extract. Herein, we analyzed 85 studies encompassing 40 hypoglycemic plants and 86 active compounds belonging to different classes of natural products: 28 flavonoids, 25 aromatic compounds, other than flavonoids, four steroids, 23 terpenoids, 4 oligosaccharides, and 1 polyalcohol. These compounds have shown to inhibit α-glucosidases, increase insulin secretion levels, increase insulin sensitivity, and block hepatic glucose output. Almost half of these molecules are not common metabolites, with a narrow taxonomic distribution, which makes them more interesting as lead molecules. Altogether, this analysis provides a necessary inventory useful for future testing of these active molecules against different hypoglycemic targets, to get a better insight into the already described mechanisms, and overall, to contribute to the knowledge of Mexican medicinal plants.

Traditional Herbal Medicine in Mesoamerica: Toward Its Evidence Base for Improving Universal Health Coverage

The quality of health care in Mesoamerica is influenced by its rich cultural diversity and characterized by social inequalities. Especially indigenous and rural communities confront diverse barriers to accessing formal health services, leading to often conflicting plurimedical systems. Fostering integrative medicine is a fundamental pillar for achieving universal health coverage (UHC) for marginalized populations. Recent developments toward health sovereignty in the region are concerned with assessing the role of traditional medicines, and particularly herbal medicines, to foster accessible and culturally pertinent healthcare provision models. In Mesoamerica, as in most regions of the world, a wealth of information on traditional and complementary medicine has been recorded. Yet these data are often scattered, making it difficult for policy makers to regulate and integrate traditionally used botanical products into primary health care. This critical review is based on a quantitative analysis of 28 survey papers focusing on the traditional use of botanical drugs in Mesoamerica used for the compilation of the "Mesoamerican Medicinal Plant Database" (MAMPDB), which includes a total of 12,537 use-records for 2188 plant taxa. Our approach presents a fundamental step toward UHC by presenting a pharmacological and toxicological review of the cross-culturally salient plant taxa and associated botanical drugs used in traditional medicine in Mesoamerica. Especially for native herbal drugs, data about safety and effectiveness are limited. Commonly used cross-culturally salient botanical drugs, which are considered safe but for which data on effectiveness is lacking constitute ideal candidates for treatment outcome studies.

Caffeoylquinic Acids with Potential Biological Activity from Plant In vitro Cultures as Alternative Sources of Valuable Natural Products

BACKGROUND

For a long time, the researchers have been looking for new efficient methods to enhance production and obtain valuable plant secondary metabolites, which would contribute to the protection of the natural environment through the preservation of various plant species, often rare and endangered. These possibilities offer plant in vitro cultures which can be performed under strictly-controlled conditions, regardless of the season or climate and environmental factors. Biotechnological methods are promising strategies for obtaining the valuable plant secondary metabolites with various classes of chemical compounds including caffeoylquinic acids (CQAs) and their derivatives. CQAs have been found in many plant species which are components in the daily diet and exhibit a wide spectrum of biological activities, including antioxidant, immunomodulatory, antihypertensive, analgesic, anti-inflammatory, hepato- and neuroprotective, anti-hyperglycemic, anticancer, antiviral and antimicrobial activities. They have also been found to offer protection against Alzheimer's disease, and play a role in weight reduction and lipid metabolism control, as well as modulating the activity of glucose-6-phosphatase involved in glucose metabolism.

METHODS

This work presents the review of the recent advances in use in vitro cultures of various plant species for the alternative system to the production of CQAs and their derivatives. Production of the secondary metabolites in in vitro culture is usually performed with cell suspension or organ cultures, such as shoots and adventitious or transformed roots. To achieve high production of valuable secondary metabolites in in vitro cultures, the optimization of the culture condition is necessary with respect to both biomass accumulation and metabolite content. The optimization of the culture conditions can be achieved by choosing the type of medium, growth regulators or growth conditions, selection of high-productivity lines or culture period, supplementation of the culture medium with precursors or elicitor treatments. Cultivation for large-scale in bioreactors and genetic engineering: Agrobacterium rhizogenes transformation and expression improvement of transcriptional factor or genes involved in the secondary metabolite production pathway are also efficient strategies for enhancement of the valuable secondary metabolites.

RESULTS

Many studies have been reported to obtain highly productive plant in vitro cultures with respect to CQAs. Among these valuable secondary metabolites, the most abundant compound accumulated in in vitro cultures was 5-CQA (chlorogenic acid). Highly productive cultures with respect to this phenolic acid were Leonurus sibiricus AtPAP1 transgenic roots, Lonicera macranthoides and Eucomia ulmoides cell suspension cultures which accumulated above 20 mg g-1 DW 5-CQA. It is known that di- and triCQAs are less common in plants than monoCQAs, but it was also possible to obtain them by biotechnological methods.

CONCLUSION

The results indicate that the various in vitro cultures of different plant species can be a profitable approach for the production of CQAs. In particular, an efficient production of these valuable compounds is possible by Lonicera macranthoides and Eucomia ulmoides cell suspension cultures, Leonurus sibiricus transformed roots and AtPAP1 transgenic roots, Echinacea angustifolia adventitious shoots, Rhaponticum carthamoides transformed plants, Lavandula viridis shoots, Sausera involucrata cell suspension and Cichorium intybus transformed roots.

Lipid oversupply induces CD36 sarcolemmal translocation via dual modulation of PKCζ and TBC1D1: an early event prior to insulin resistance

Lipid oversupply may induce CD36 sarcolemmal translocation to facilitate fatty acid transport, which in turn causes dyslipidemia and type 2 diabetes. However, the underlying mechanisms of CD36 redistribution are still yet to be unraveled.

Methods: High fat diet fed mice and palmitate/oleic acid-treated L6 cells were used to investigate the initial events of subcellular CD36 recycling prior to insulin resistance. The regulation of CD36 sarcolemmal translocation by lipid oversupply was assessed by insulin tolerance test (ITT), oral glucose tolerance test (OGTT), glucose/fatty acid uptake assay, surface CD36 and GLUT4 detection, and ELISA assays. To elucidate the underlying mechanisms, specific gene knockout, gene overexpression and/or gene inhibition were employed, followed by Western blot, co-immunoprecipitation, immunostaining, and kinase activity assay.

Results: Upon lipid/fatty acid overload, PKCζ activity and TBC1D1 phosphorylation were enhanced along with increased sarcolemmal CD36. The inhibition of PKCζ or TBC1D1 was shown to block fatty acid-induced CD36 translocation and was synergistic in impairing CD36 redistribution. Mechanically, we revealed that AMPK was located upstream of PKCζ to control its activity whereas Rac1 facilitated PKCζ translocation to the dorsal surface of the cell to cause actin remodeling. Furthermore, AMPK phosphorylated TBC1D1 to release retained cytosolic CD36. The activated PKCζ and phosphorylated TBC1D1 resulted in a positive feedback regulation of CD36 sarcolemmal translocation.

Conclusion: Collectively, our study demonstrated exclusively that lipid oversupply induced CD36 sarcolemmal translocation via dual modulation of PKCζ and TBC1D1, which was as an early event prior to insulin resistance. The acquired data may provide potential therapy targets to prevent lipid oversupply-induced insulin resistance.

Scopoletin increases glucose uptake through activation of PI3K and AMPK signaling pathway and improves insulin sensitivity in 3T3-L1 cells

Coumarins have been shown to reduce blood glucose levels and improve insulin sensitivity in other studies. The purpose of this study was to investigate the effects of scopoletin, which is a type of coumarin family, on glucose uptake in 3T3-L1 cells to test the hypothesis that scopoletin exerts an antidiabetic function on adipocytes. Scopoletin significantly increased glucose uptake, which was associated with increased expression of the plasma membrane glucose transporter type 4 (PM-GLUT4) in 3T3-L1 adipocytes. This increase in PM-GLUT4 expression was promoted by phosphorylation of protein kinase B, activation of phosphatidylinositol-3-kinase (PI3K), and enhanced intracellular glucose uptake. Scopoletin also promoted phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and enhanced PM-GLUT4 expression. Scopoletin-induced glucose uptake in 3T3-L1 adipocytes was inhibited by treatment with the PI3K inhibitor wortmannin and the AMPK inhibitor compound C. These results suggest that scopoletin has an antidiabetic effect by stimulating GLUT4 translocation to the PM through activation of the PI3K and AMPK pathways in 3T3-L1 adipocytes, thereby upregulating glucose uptake.

Fucoidan from Undaria pinnatifida has anti-diabetic effects by stimulation of glucose uptake and reduction of basal lipolysis in 3T3-L1 adipocytes

Fucoidan, a sulfated polysaccharide derived from brown seaweeds, has been shown to reduce blood glucose levels and improve insulin sensitivity in mice. We investigated the effects of fucoidan on lipid accumulation, lipolysis, and glucose uptake in 3T3-L1 cells to test the hypothesis that fucoidan exerts an anti-diabetic function by acting directly on adipocytes. The 3T3-L1 cells were treated with 10, 50, 100, and 200 μg/mL of fucoidan from Undaria pinnatifida. Oil Red O staining and AdipoRed assay were used to determine lipid accumulation during adipocyte differentiation. Fucoidan was shown to reduce lipid accumulation and glycerol-3-phosphate dehydrogenase (GPDH) activity in a dose-dependent manner (P < .01). The expression of peroxisome proliferator-activated receptor γ (PPARγ), a major transcription factor associated with adipocyte differentiation, was also suppressed upon treatment with fucoidan. Treatment with fucoidan stimulated glucose uptake in normal adipocytes and restored insulin-stimulated glucose uptake in obesity-induced insulin resistant adipocytes, which were made by incubating hypertrophied 3T3-L1 cells with the conditioned media of RAW 264.7 macrophages (RAW-CM) (P < .01). In the presence of RAW-CM, fucoidan enhanced epinephrine-stimulated lipolysis but reduced basal lipolysis, as determined by non-esterified fatty acid into the culture medium (P < .001). These results suggest that fucoidan may have anti-diabetic effects by improving insulin-stimulated glucose uptake and inhibiting basal lipolysis in adipocytes without inducing adipogenesis.

Distinct Fractions of an Artemisia scoparia Extract Contain Compounds With Novel Adipogenic Bioactivity

Adipocytes are important players in metabolic health and disease, and disruption of adipocyte development or function contributes to metabolic dysregulation. Hence, adipocytes are significant targets for therapeutic intervention in obesity and metabolic syndrome. Plants have long been sources for bioactive compounds and drugs. In previous studies, we screened botanical extracts for effects on adipogenesis in vitro and discovered that an ethanolic extract of Artemisia scoparia (SCO) could promote adipocyte differentiation. To follow up on these studies, we have used various separation methods to identify the compound(s) responsible for SCO's adipogenic properties. Fractions and subfractions of SCO were tested for effects on lipid accumulation and adipogenic gene expression in differentiating 3T3-L1 adipocytes. Fractions were also analyzed by Ultra Performance Liquid Chromatography- Mass Spectrometry (UPLC-MS), and resulting peaks were putatively identified through high resolution, high mass accuracy mass spectrometry, literature data, and available natural products databases. The inactive fractions contained mostly quercetin derivatives and chlorogenates, including chlorogenic acid and 3,5-dicaffeoylquinic acid, which had no effects on adipogenesis when tested individually, thus ruling them out as pro-adipogenic bioactives in SCO. Based on these studies we have putatively identified the principal constituents in SCO fractions and subfractions that promoted adipocyte development and fat cell gene expression as prenylated coumaric acids, coumarin monoterpene ethers, 6-demethoxycapillarisin and two polymethoxyflavones.

Phytochemical characterization and comparative studies of four Cecropia species collected in Panama using multivariate data analysis

Plant species of the genus Cecropia (Urticaceae) are used as traditional medicine in Latin-America, and are commercially available as food supplements. The aim of this study was to characterize and compare the phytochemical constituents of four Cecropia species collected in Panama. The structures of 11 compounds isolated from leaves of C. obtusifolia were elucidated based on high resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) spectroscopic analysis; the polyphenolic constituents of leaves of all four Cecropia species and commercial products were characterized using high performance liquid chromatography-diode array detection-quadrupole time of flight-tandem high resolution mass spectrometry (HPLC-DAD-QTOF). Forty-seven compounds were fully identified or tentatively characterized. Thirty-nine of these have not been previously reported for the species under investigation. Multivariate analysis revelead that C. obtusifolia and C. insignis are the most related species, while C. hispidissima is the most segregated one. Considering the importance of the description of novel chemical entities and the increasing interest and use of natural products, this study may be of great help for chemotaxonomic purposes, the interpretation of medicinal properties and for quality assessment of herbal supplements containing Cecropia leaves.

Chemistry and Biology of Selected Mexican Medicinal Plants

Herbal medicines are an integral element of alternative medical care in Mexico, and the best testimony to their efficacy and cultural value is their persistence in contemporary Mexican marketplaces where the highest percentages of medicinal and aromatic plants are sold. This chapter summarizes current trends in research on medicinal plants in Mexico, with emphasis on work carried out at the authors' laboratories. The most relevant phytochemical and pharmacological profiles of a selected group of plants used widely for treating major national health problems are described.From this contribution, it is evident that in the last five decades a significant amount of research on medicinal plants has been performed by Mexican scientists. Such efforts have led to the publication of many research papers in noted peer-reviewed journals and technical books. The isolation and structural characterization of hundreds of bioactive secondary metabolites have been accomplished, and most importantly, these studies have tended to support the ethnomedical uses of many different species. A multidisciplinary approach for investigating these plants has led to an increased emphasis on areas such as phytopharmacology, phytotoxicology, quality control, regulation, and conservation issues for these valuable resources. The medicinal plants analyzed so far have shown a very broad chemical diversity of their constituents, which have a high potential for exhibiting novel mechanistic effects biologically. The chapter shows also that there is need to conduct additional clinical studies on herbal drugs, in particular because the longstanding traditional evidence for their safety is not always sufficient to assure their rational use. There is also need to move to "omics" approaches for investigating the holistic effect and the influence of groups of phytochemicals on the whole organism. Mexican scientists may be expected to have bright prospects in this regard, which will imbue medicinal plant research with a new dynamism in the future.

Smilax aristolochiifolia Root Extract and Its Compounds Chlorogenic Acid and Astilbin Inhibit the Activity of α-Amylase and α-Glucosidase Enzymes

Regulating activities of α-amylase and α-glucosidase through the use of specific inhibitors is a main strategy for controlling type 2 diabetes. Smilax aristolochiifolia root decoctions are traditionally used in Mexico as hypoglycemic and for weight loss, but the active principles and mechanisms underlying such putative metabolic effects are yet unknown. Here, we isolated the major bioactive compounds from a hydroethanolic extract of S. aristolochiifolia root by fast centrifugal partition chromatography and evaluated their effects against pancreatic α-amylase and yeast α-glucosidase. A chlorogenic acid-rich fraction (CAF) inhibited α-amylase activity with an IC₅₀ value of 59.28 μg/mL in an uncompetitive manner and α-glucosidase activity with an IC₅₀ value of 9.27 μg/mL in a noncompetitive mode. Also, an astilbin-rich fraction (ABF) inhibited α-glucosidase activity with an IC₅₀ value of 12.30 μg/mL, in a noncompetitive manner. CAF inhibition α-amylase was as active as acarbose while both CAF and ABF were 50-fold more potent inhibitors of α-glucosidase than acarbose. The molecular docking results of chlorogenic acid and astilbin with α-amylase and α-glucosidase enzymes correlated with the inhibition mechanisms suggested by enzymatic assays. Our results prove that S. aristolochiifolia roots contain chlorogenic acid and astilbin, which inhibit carbohydrates-hydrolyzing enzymes, suggesting a new mechanism for the hypoglycemic effect reported for this plant.

In vitro anti-diabetic effect of flavonoids and pheophytins from Allophylus cominia Sw. on the glucose uptake assays by HepG2, L6, 3T3-L1 and fat accumulation in 3T3-L1 adipocytes

BACKGROUND AND PURPOSE

Based on ethno-botanical information collected from diabetic patients in Cuba and firstly reported inhibition of PTP1B and DPPIV enzymes activities, Allophylus cominia (A. cominia) was identified as possible source of new drugs that could be used for the treatment of type 2 diabetes mellitus (T2-DM).

EXPERIMENTAL APPROACH

in this study, the activity of the characterised extracts from A. cominia was tested on the glucose uptake using HepG2 and L6 cells, 3T3-L1 fibroblasts and adipocytes as well as their effect on the fat accumulation using 3T3-L1 adipocytes.

KEY RESULTS

on 2-NBDG glucose uptake assay using HepG2 and L6 cells, extracts from A. cominia enhanced insulin activity by increasing glucose uptake. On HepG2 cells Insulin EC₅₀ of 93 ± 21nM decreased to 13 ± 2nM in the presence of the flavonoids mixture from A.cominia. In L6 cells, insulin also produced a concentration-dependent increase with an EC₅₀ of 28.6 ± 0.7nM; EC₅₀ decreased to 0.08 ± 0.02nM and 5 ± 0.9nM in the presence of 100μg/ml of flavonoids and pheophytins mixtures, respectively. In 3T3-L1 fibroblasts, insulin had an EC₅₀ of >1000nM that decreased to 38 ± 4nM in the presence of the flavonoids extract. However, in adipocytes, insulin produced a significant concentration-dependent increase and an EC₅₀ of 30 ± 8nM was a further confirmation of the insulin responsiveness of the adipocytes to the insulin. At 100µg/ml, flavonoids and pheophytins extracts decreased fat accumulation in 3T3-L1 adipocytes by two folds in comparison to the control differentiated cells (p < 0.05). The crude extract of A. cominia did not show any enhancement of 2-NBDG uptake by 3T3-L1 adipocytes in the presence or absence of 100nM insulin. In addition, in fully differentiated adipocytes, both extracts produced significant decrease in lipid droplets in the cells and no lipid accumulation were seen after withdrawal of the extracts from the cell growth medium. However, there was no effect of both extracts on total protein concentration in cells as well as on Glut-4 transporters.

CONCLUSIONS AND IMPLICATIONS

the pharmacological effects of the extracts from A. cominia observed in experimental diabetic models were shown in this study. A. cominia is potentially a new candidate for the treatment and management of T2-DM.

Current trends in small molecule discovery targeting key cellular signaling events towards the combined management of diabetes and obesity

Non-insulin dependent diabetes mellitus, also known as Type 2 diabetes is a polygenic disorder leading to abnormalities in the carbohydrate and lipid metabolism. The major contributors in the pathophysiology of type 2 diabetes (T2D) include resistance to insulin action, β cell dysfunction, an abnormality in glucose metabolism and storage, visceral obesity and to some extent inflammation and oxidative stress. Insulin resistance, along with a defect in insulin secretion by the pancreatic β cells is instrumental towards progression to hyperglycemia. Increased incidence of obesity is also a major contributing factor in the escalating rates of type 2 diabetes. Drug discovery efforts are therefore crucially dependent on identifying individual molecular targets and validating their relevance to human disease. The current review discusses bioactive compounds from medicinal plants offering enhanced therapeutic potential for the combined patho-physiology of diabetes and obesity. We have demonstrated that 3β-taraxerol a pentacyclic triterpenoid (14-taraxeren-3-ol) isolated from the ethyl acetate extract of Mangifera indica, chlorogenic acid isolated from the methanol extract of Cichorium intybus, methyl tetracosanoate from the methanol extract of Costus pictus and vitalboside A derived from methanolic extract of Syzygium cumini exhibited significant effects on insulin stimulated glucose uptake causing insulin sensitizing effects on 3T3L1 adipocytes (an in vitro model mimicking adipocytes). Whereas, (3β)-stigmast-5-en-3-ol isolated from Adathoda vasica and Aloe emodin isolated from Cassia fistula showed significant insulin mimetic effects favoring glucose uptake in L6 myotubes (an in vitro model mimicking skeletal muscle cells). These extracts and molecules showed glucose uptake through activation of PI3K, an important insulin signaling intermediate. Interestingly, cinnamic acid isolated from the hydro-alcohol extract of Cinnamomum cassia was found to activate glucose transport in L6 myotubes through the involvement of GLUT4 via the PI3K-independent pathway. However, the activation of glucose storage was effective in the presence of 3β-taraxerol and aloe emodin though inhibition of GSK3β activity. Therefore, the mechanism of improvement of glucose and lipid metabolism exhibited by the small molecules isolated from our lab is discussed. However, Obesity is a major risk factor for type-2 diabetes leading to destruction of insulin receptors causing insulin resistance. Identification of compounds with dual activity (anti-diabetic and antiadipogenic activity) is of current interest. The protein tyrosine phosphatase 1B (PTP1B) is an important negative regulator of the insulin and leptin-signaling pathway is of significance in target definition and discovery.

Effect of Chlorogenic Acid Administration on Glycemic Control, Insulin Secretion, and Insulin Sensitivity in Patients with Impaired Glucose Tolerance

Chlorogenic acid has been described as a novel polyphenol with metabolic effects on glucose homeostasis. The aim of this study was to evaluate the effect of chlorogenic acid administration on glycemic control, insulin secretion, and insulin sensitivity in patients with impaired glucose tolerance (IGT). A randomized, double-blind, placebo-controlled clinical trial was performed in 30 patients with IGT; 15 patients randomly assigned to oral chlorogenic acid received 400 mg three times per day for 12 weeks, and the other 15 patients received placebo in the same way. Before and after the intervention, anthropometric and metabolic measurements, including fasting plasma glucose (FPG), glycated hemoglobin A1c, and a lipid profile, were performed. Area under the curve of glucose and insulin as well as the insulinogenic, Stumvoll, and Matsuda indices were calculated. Wilcoxon, Mann-Whitney U, and chi-square tests were performed, and P ≤ .05 was considered statistically significant. There were significant decreases in FPG (5.7 ± 0.4 vs. 5.5 ± 0.4 mmol/L, P = .002), insulinogenic index (0.71 ± 0.25 vs. 0.63 ± 0.25, P = .028), body weight, body mass index, waist circumference, triglycerides, total cholesterol, low-density lipoprotein cholesterol, and very low-density lipoprotein levels in the chlorogenic acid group, with an increment in the Matsuda index (1.98 ± 0.88 vs. 2.30 ± 1.23, P = .002). There were no significant differences in the placebo group. In conclusion, chlorogenic acid administration in patients with IGT decreased FPG and insulin secretion, while increasing insulin sensitivity and improving both anthropometric evaluations and the lipid profile.

Selection of chemical markers for the quality control of medicinal plants of the genus Cecropia

CONTEXT

Several Cecropia (Cecropiaceae) species are traditionally used in Latin America for the treatment of a variety of diseases including diabetes, arterial hypertension, asthma, bronchitis, anxiety, and inflammation. At present, a number of commercial products based on these plants have been introduced into the market with very little information on methods for guaranteeing their quality and safety.

OBJECTIVE

This work proposes potential chemical markers for the quality control of the raw materials of Cecropia obtusifolia Bertol., Cecropia peltata L., Cecropia glaziovii Snethl., Cecropia pachystachya Trécul, and Cecropia hololeuca Miq.

METHODS

The Herbal Chemical Marker Ranking System (Herb MaRS) developed by the National Institute of Complementary Medicine (NICM) at the University of Western Sydney was used for selecting chemical markers for the quality control of selected medicinal species of Cecropia. This review covers the period from 1982 to 2016.

RESULTS

Chlorogenic acid, flavonoidal glycosides (orientin, isoorientin, vitexin, isovitexin, and rutin), catechin, epicatechin, procyanidins (B2, B5, and C1), steroids (β-sitosterol), and triterpenoids (α-amyrin, pomolic, tormentic and ursolic acids) were selected as chemical markers for the quality control of the leaves.

CONCLUSION

It is necessary to establish comprehensive standards for guaranteeing quality, safety and efficacy of herbal drugs. The selection of adequate chemical markers for quality control purposes requires a good knowledge about the chemical composition of medicinal plants and their associated biological properties. To the best of our knowledge this review article is the first to address the identification and quantitative determination of the chemical markers for the genus Cecropia.

Antidiabetic plant-derived nutraceuticals: a critical review

Diabetes mellitus (DM) is one of the major health problems in the world, especially amongst the urban population. Chemically synthesized drugs used to decrease the ill effects of DM and its secondary complications cause adverse side effects, viz., weight gain, gastrointestinal disturbances, and heart failure. Currently, various other approaches, viz., diet control, physical exercise and use of antidiabetic plant-derived molecules/foods are advocated to manage DM, as they are economical with fewer or no side effects. This review mainly focuses on antidiabetic plants, chemically characterized plant molecules and plant-based foods in the treatment of DM. Very little science-based evidence is available on the mechanism of action of plant-derived food molecules on the DM targets. Critical DM targets include α-amylase, α-glucosidase, DPP-IV, aldose reductase, PPAR-γ, AMP kinase and GLUT4. In-depth studies carried out on a few of those targets with specific mechanisms of action are addressed in this review. This review may help future researchers in identifying a right plant molecule to treat DM or to develop food formulations for DM management.

Flavonoids from Tetracera indica Merr. induce adipogenesis and exert glucose uptake activities in 3T3-L1 adipocyte cells

BACKGROUND

Tetracera indica Merr. (Family: Dilleniaceae), known to the Malay as 'Mempelas paya', is one of the medicinal plants used in the treatment of diabetes in Malaysia. However, no proper scientific study has been carried out to verify the traditional claim of T. indica as an antidiabetic agent. Hence, the aims of the present study were to determine the in vitro antidiabetic potential of the T. indica stems ethanol extract, subfractions and isolated compounds.

METHODS

The ethanol extract and its subfractions, and isolated compounds from T. indica stems were subjected to cytotoxicity test using MTT viability assay on 3T3-L1 pre-adipocytes. Then, the test groups were subjected to the in vitro antidiabetic investigation using 3T3-L1 pre-adipocytes and differentiated adipocytes to determine the insulin-like and insulin sensitizing activities. Rosiglitazone was used as a standard antidiabetic agent. All compounds were also subjected to fluorescence glucose (2-NBDG) uptake test on differentiated adipocytes. Test solutions were introduced to the cells in different safe concentrations as well as in different adipogenic cocktails, which were modified by the addition of compounds to be investigated and in the presence or absence of insulin. Isolation of bioactive compounds from the most effective subfraction (ethyl acetate) was performed through repeated silica gel and sephadex LH-20 column chromatographies and their structures were elucidated through 1H-and 13C-NMR spectroscopy.

RESULTS

Four monoflavonoids, namely, wogonin, norwogonin, quercetin and techtochrysin were isolated from the T. indica stems ethanol extract. Wogonin, norwogonin and techtochrysin induced significant (P < 0.05) adipogenesis like insulin and enhanced adipogenesis like rosiglitazone. Wogonin and norwogonin also exhibited significant (P < 0.05) glucose uptake activity.

CONCLUSION

The present study demonstrated that the flavonoids isolated from the T. indica stems possess antidiabetic potential revealing insulin-like and insulin-sensitizing effects which were significant among the compounds. This also rationalizes the traditional use of T. indica in the management of diabetes in Malaysia.

Intestinal α-Glucosidase Inhibitors in Achillea millefolium

Achillea millefolium is a plant used as a component of anti-diabetic preparation but the bioactive compounds responsible for its use are not known. Inhibition of intestinal α-glucosidase is a preferable effect for prevention and treatment of diabetes, and A. millefolium extract showed inhibitory activity against the enzyme. Activity-guided separation of the extract gave four mono- or di-caffeoylquinic acids as the isolate. Quantitation of these four caffeoylquinic acids and the activity of the isolates suggested that these are the major contributor for the α-glucosidase inhibitory activity in the extract. However also, the presence of unidentified, minor, but potent α-glucosidase inhibitor in the isolate was also suggested.

Potential of the chlorogenic acid as multitarget agent: Insulin-secretagogue and PPAR α/γ dual agonist

The chlorogenic acid (CGA) is a natural product isolated from Cecropia obtusifolia, which possesses several pharmacological properties, such as: anti-carcinogenic, neuroprotective, antioxidant, anti-inflammatory, hypoglycemic, and hypolipidemic. In relation to its effects on the hyperglycemia and hypertriglyceridemia, few is known about the mechanisms in which this compound may be acting, therefore, the aim of the present study was to determine if CGA acts as an insulin secretagogue increasing intracellular calcium concentrations ([Ca²⁺]_i) in RINm5F cells; or as an insulin sensitizer and lipid-lowering agent stimulating the expression of PPARγ and PPARα, respectively, in 3T3-L1 adipocytes. As results, RINm5F cells treated with 200μM of CGA showed an increase in [Ca²⁺]_i of 9-times versus control and 4-times as compared to positive control; in addition, an increase in insulin secretion was observed similarly to those of positive control. CGA also significantly increased the mRNA expression of PPARγ (150%) and GLUT4 (220%), as well PPARα (40%) and FATP (25%) as it was appreciated by RT-PCR. Additionally, a chemoinformatic analysis suggested that CGA has suitable physicochemical properties to be considered as leader bioactive molecule for the development of novel agents with similar properties. Together, our results indicate that CGA possesses multiple mechanisms of action for the development of highly effective therapeutics in the treatment of metabolic diseases such as type 2 diabetes.

Histochemistry and immunolocalisation of glucokinin in antidiabetic plants used in traditional Mexican medicine

Mexico is a megadiverse country that has 3,600 to 4,000 species of medicinal plants, of which approximately 800 are used to treat conditions related to diabetes mellitus (DM). DM is a chronic degenerative disease of energy metabolism that exists as two types: type 1 (DM1) and type 2 (DM2). DM is considered a public health problem that affects 7% of the Mexican population older than 20 years. DM is clinically controlled with hypoglycaemic drugs, alpha-glucosidase inhibitors, insulin secretion stimulants or the direct application of insulin. The hypoglycaemic effectiveness of specific molecules has been determined only for some medicinal plants in Mexico used to treat DM2. The presence of molecules called glucokinins, wich are similar to animal insulin molecules, has been reported in some plant species; glucokinins act as both growth factors and regulators of glucose metabolism in plants. Therefore, we hypothesized that the hypoglycaemic effectiveness of some of the popularly used species for the control of DM could be due to the presence of glucokinin, as reported for Bauhinia variegata. The goal of this work was to use histochemistry to detect, the accumulation of protein that is immunocytochemically compatible with glucokinin in slide sections of hypoglycaemic species used as remedies for DM2. The top fourteen most used medicinal plants in Mexico were selected for study via microscopic sections. Proteins were histochemically detected using naphthol blue black and Johansen's quadruple stain, and the immunocytochemical correspondence of the proteins with glucokinin was investigated using an insulin antibody. All species studied reacted positively to proteins and glucokinin in the same structures. The presence of glucokinin in these structures and the corresponding hypoglycaemic effects are discussed in the contex of the actions of other compounds.

In vitro anti-diabetic activity of flavonoids and pheophytins from Allophylus cominia Sw . on PTP1B, DPPIV, alpha-glucosidase and alpha-amylase enzymes

BACKGROUND

Ethno-botanical information from diabetic patients in Cuba led to the identification of Allophylus cominia as a possible source of new drugs for the treatment of type 2 diabetes mellitus (T2-DM).

EXPERIMENTAL

Chemical characterization of the extracts from A. cominia was carried out using chromatographic and spectroscopic methods. The extracts were tested for their activity on PTP1B, DPPIV, α-glucosidase enzymes and α-amylase.

RESULTS

The flavonoid rich fractions from A. cominia inhibited DPPIV enzyme (75.3±2.33%) at 30µg/ml and produced a concentration-dependent inhibition against DPPIV with a Ki value of 2.6µg/ml. At 30µg/ml, flavonoids and pheophytins extracts significantly inhibited PTP1B enzyme (100±2.6% and 68±1% respectively). The flavonoids, pheophytin A and pheophytin B fractions showed significant concentration-dependent inhibition against PTP1B with Ki values of 3µg/ml, 0.64µg/ml and 0.88µg/ml respectively. At 30µg/ml, the flavonoid fraction significantly inhibited α-glucosidase enzyme (86±0.3%) in a concentration-dependent pattern with a Ki value of 2µg/ml. None of the fractions showed significant effects on α-amylase. Fatty acids, tannins, pheophytins A and B, and a mixture of flavonoids were detected in the methanolic extract from A. cominia. The identified flavonoids were mearnsitrin, quercitrin, quercetin-3-alloside, and naringenin-7-glucoside.

CONCLUSION

The pharmacological effects of the extracts from A. cominia earlier observed in experimental diabetic models was confirmed in this study. Thus a new drug or formulation for the treatment of T2-DM could be developed from A. cominia.

Chemical composition, phytochemical constituents, antioxidant and anti-inflammatory activities of Urtica urens L. leaves

OBJECTIVE

The aim of this study was to investigate the chemical composition and antioxidant properties of Urtica urens L.(Uu) as well as its anti-inflammatory effect on carrageenan (CARR)-induced paw oedema in rats.

METHODS

The leaves were extracted using ethanol (EtOH) and water. The extracts were analysed for proximate composition and antioxidant activity using standard chemical analysis methods.

RESULTS

The proximate analysis showed that Uu leaves contained appreciable percentages of dry mass, ashes, carbohydrates, proteins, lipids, sugars, anthocyanin, carotenoid and fibre. Results showed that EtOH extract contained the highest amount of total phenolics, flavonoids, tannins, ortho-diphenols and flavonols. It decreased the paw oedema after CARR administration, and ameliorated the activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and the malondialdehyde (MDA).

CONCLUSIONS

Uu displayed a high potential as a natural source of minerals, phytochemicals and antioxidant properties. EtOH extract exhibited a significant inhibition against CARR-induced inflammation.

Plants used in the traditional medicine of Mesoamerica (Mexico and Central America) and the Caribbean for the treatment of obesity

ETHNOPHARMACOLOGICAL RELEVANCE

Obesity is a worldwide medical concern. New ethnobotanical information regarding the antiobesity effect of medicinal plants has been obtained in the last 30 years in response to socio-demographic changes and high-fat diets became common.

AIM OF THE STUDY

This review provides a summary of medicinal plants used in Mexico, Central America and the Caribbean for the empirical treatment of obesity in terms of ethnobotany, toxicity, pharmacology, conservation status, trade and chemistry.

MATERIALS AND METHODS

Bibliographic investigation was performed by analyzing recognized books, undergraduate and postgraduate theses and peer-reviewed scientific articles, consulting worldwide accepted scientific databases from the last four decades. Medicinal plants used for the treatment of obesity were classified in two categories: (1) plants with pharmacological evidence and (2) plants without pharmacological evidence.

RESULTS

A total of 139 plant species, belonging to 61 families, native to Mexico, Central America and the Caribbean that are used for the empirical treatment of obesity were recorded. From these plants, 33 were investigated in scientific studies, and 106 plants lacked scientific investigation. Medicinal plants were experimentally studied in vitro (21 plants) and in vivo (16 plants). A total of 4 compounds isolated from medicinal plants used for the empirical treatment of obesity have been tested in vitro (2 compounds) and in vivo (4 compounds) studies. No clinical trials on obese subjects (BMI>30 kg/m(2)) have been performed using the medicinal plants cited in this review. There are no herbal-based products approved in Mexico for the treatment of obesity.

CONCLUSIONS

There are a limited number of scientific studies published on medicinal plants from Mexico, Central America and the Caribbean used for the treatment of obesity. This review highlights the need to perform pharmacological, phytochemical, toxicological and ethnobotanical studies with medicinal flora to obtain new antiobesity agents.

Antidiabetic plants improving insulin sensitivity

BACKGROUND

Globally, the prevalence of diabetes mellitus is increasing at an alarming rate. This chronic pathology gravely troubled the human health and quality of life. Both insulin deficiency and insulin resistance are involved in the pathophysiology of diabetes mellitus. Moreover, insulin resistance is being diagnosed nowadays in a growing population of diabetic and obese patients, especially in industrialized societies. There are lots of conventional agents available to control and to treat diabetes, but total recovery from this disorder has not been reported up to this date. Plants provided a potential source of hypoglycemic drugs and are widely used in several traditional systems of medicine to prevent diabetes. A few reviews with less attention paid to mechanisms of action have been published on antidiabetic plants.

OBJECTIVES

The present review focuses on the various plants that have been reported to be effective in improving insulin sensitivity associated with diabetes.

KEY FINDINGS

In this work, an updated systematic review of the published literature has been conducted to review the antidiabetic plants improving insulin sensitivity and 111 medicinal plants have been reported to have a beneficial effect on insulin sensitivity using several in-vitro and in-vivo animal models of diabetes.

CONCLUSION

The different metabolic and cellular effects of the antidiabetic plants improving insulin sensitivity are reported indicating the important role of medicinal plants as potential alternative or complementary use in controlling insulin resistance associated with diabetes mellitus.

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.

A perspective on natural products research and ethnopharmacology in Mexico: the eagle and the serpent on the prickly pear cactus

Mexico's extraordinarily rich cultural and floristic diversity has fascinated explorers and researchers ever since the "New World" was discovered for and by Europeans. For many decades, natural product research has been a very active field of research in Mexico, and there also are some ongoing ethnopharmacological research efforts. This review provides an overview and critical appraisal on some key developments in these fields and examples of medicinal plants used by indigenous communities that have become of great local importance in Mexican popular medicine. In this review, the focus is on plants with effects on the CNS, diabetes, metabolic syndrome, inflammatory processes, and gastrointestinal disorders. While some of the major food plants consumed worldwide originate from southern North America, only very few medicinal plants have become of major global importance. Opuntia species are now used increasingly to manage diabetes and metabolic syndrome and represent an example of a novel medicinal product/supplement. Undoubtedly, narcotic and mind-altering drugs both have received the widest scientific interest and have attracted considerable popular attention. The history of use of the indigenous Mexican Materia Medica in the context of research on local and popular resources specifically with regard to the diverse challenges in the context of studying the world's biodiversity and the development of comparative and semiquantitative ethnobotanical research methods is discussed herein. Natural product and ethnopharmacological research in Mexico seems to have been influenced by the political and societal developments originating from the Convention on Biological Diversity (CBD) and subsequent conventions, which have not yet had the desired effect of giving value to these local resources, as they might deserve. Their equitable and sustainable implementation remains a challenge. Natural product research and ethnopharmacology will play a key role in developing an adequate evidence base for such products derived from local and traditional knowledge in Mexico.