Salacia oblonga improves cardiac fibrosis and inhibits postprandial hyperglycemia in obese zucker rats

A Comprehensive Approach to Derivatization: Elemental Composition, Biochemical, and In Silico Studies of Metformin Derivatives Containing Copper and Zinc Complexes

The current study was designed to synthesize, characterize, and screen the molecular and biological activities of different metformin derivatives that possess potent antidiabetic potential with minimal side-effects. Metformin-based derivatives containing the metal complexes Cu II (MCu1-MCu9) and Zn II (MZn1-MZn9) were generated using aromatic aldehydes and ketones in a template process. The novel metal complexes were characterized through elemental analysis, physical state, melting point, physical appearance, Fourier-transform infrared (FTIR) spectroscopy, UV/visible (UV/Vis) spectroscopy, ¹H nuclear magnetic resonance (NMR) spectroscopy, and ¹³C-NMR spectroscopy. Screening for inhibitory activity against the enzymes α-amylase and α-glucosidase, and molecular simulations performed in Schrödinger were used to assess the synthesized derivatives' biological potential. Met1, Met2, Met3, and Met8 all displayed activities that were on par with the reference in an enzymatic inhibition assay (amylase and glucosidase). The enzyme inhibition assay was corroborated by molecular simulation studies, which also revealed a competitive docking score compared to the gold standard. The Swiss ADME online web server was utilized to compute ADME properties of metformin analogues. Lipinski's rule of five held true across all derivatives, making it possible to determine the percentage of absorption. Metformin derivatives showed significant antidiabetic activities against both targeted enzymes, and the results of this work suggest that these compounds could serve as lead molecules for future study and development.

A systematic analysis of anti-diabetic medicinal plants from cells to clinical trials

Background

Diabetes is one of the fastest-growing health emergencies of the 21st century, placing a severe economic burden on many countries. Current management approaches have improved diabetic care, but several limitations still exist, such as decreased efficacy, adverse effects, and the high cost of treatment, particularly for developing nations. There is, therefore, a need for more cost-effective therapies for diabetes management. The evidence-based application of phytochemicals from plants in the management of diseases is gaining traction.

Methodology

Various plants and plant parts have been investigated as antidiabetic agents. This review sought to collate and discuss published data on the cellular and molecular effects of medicinal plants and phytochemicals on insulin signaling pathways to better understand the current trend in using plant products in the management of diabetes. Furthermore, we explored available information on medicinal plants that consistently produced hypoglycemic effects from isolated cells to animal studies and clinical trials.

Results

There is substantial literature describing the effects of a range of plant extracts on insulin action and insulin signaling, revealing a depth in knowledge of molecular detail. Our exploration also reveals effective antidiabetic actions in animal studies, and clear translational potential evidenced by clinical trials.

Conclusion

We suggest that this area of research should be further exploited in the search for novel therapeutics for diabetes.

Critical Assessment of In Vitro Screening of α-Glucosidase Inhibitors from Plants with Acarbose as a Reference Standard

Postprandial hyperglycemia is treated with the oral antidiabetic drug acarbose, an intestinal α-glucosidase inhibitor. Side effects of acarbose motivated a growing number of screening studies to identify novel α-glucosidase inhibitors derived from plant extracts and other natural sources. As "gold standard", acarbose is frequently included as the reference standard to assess the potency of these candidate α-glucosidase inhibitors, with many outperforming acarbose by several orders of magnitude. The results are subsequently used to identify suitable compounds/products with strong potential for in vivo efficacy. However, most α-glucosidase inhibitor screening studies use enzyme preparations obtained from nonmammalian sources (typically Saccharomyces cerevisiae), despite strong evidence that inhibition data obtained using nonmammalian α-glucosidase may hold limited value in terms of identifying α-glucosidase inhibitors with actual in vivo hypoglycemic potential. The aim was to critically discuss the screening of novel α-glucosidase inhibitors from plant sources, emphasizing inconsistencies and pitfalls, specifically where acarbose was included as the reference standard. An assessment of the available literature emphasized the cruciality of stating the biological source of α-glucosidase in such screening studies to allow for unambiguous and rational interpretation of the data. The review also highlights the lack of a universally adopted screening assay for novel α-glucosidase inhibitors and the commercial availability of a standardized preparation of mammalian α-glucosidase.

Hypericum Perforatum L. Hairy Root Extracts – Regulation of Glycemic, Metabolic, Serum Enzyme and Lipid Profile in Stz - Induced Diabetic Rats

Apart from currently available therapeutics for the treatment of diabetes mellitus, much attention has been paid to discover phytochemicals from natural resources, mainly due to their low side-effects. Hypericum perforatum hairy root (HR) transformed with Agrobacterium rhizogenes A4 represent prospective experimental system enriched in xanthones, known as potent antidiabetic agents. Thus, the aim of this study was to evaluate HR extracts for their potential antihyperglycemic activity in streptozotocin (STZ)-induced diabetic rats, also compared to the effects of wild-growing Hyperici herba (HH). We conducted an acute-toxicity study, multiple dose study, and 24h blood glucose measurements after a single dose administration of HH and HR (200 mg/kg) in diabetic rats. Furthermore, we examined the effects of 14-days administration of HH and HR extracts on blood glucose levels, metabolic parameters, enzyme, and lipid status in healthy and diabetic rats. Both extracts produced a fall of about 70% in blood glucose level after 24h of administration. Two-week treatment with HH and HR induced a significant decrease (70-72%) in blood glucose levels. Moreover, we found an improvement of the dysregulated metabolic parameters (body weight, food, and water consumption and urine output). Serum enzyme (AST, ALT, and γ-GT) and lipid profile parameters (CHOL, TAG, and HDL) were also improved by both extracts. These findings might provide a new insight for managing diabetic hyperglycemia and dysregulated serum enzyme and lipid profile, using extracts from transgenic roots cultures from H. perforatum.

Characterization of the chemical profile and the effects of ethanolic extracts of Maytenus ilicifolia Mart. ex Reissek on glucose metabolism in normal hyperglycemic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Maytenus ilicifolia Mart. ex Reissek, Celastraceae, is popularly known as "espinheira-santa" and used to treat pathologies related to the stomach. However, in popular culture, this species has also been used to treat other disorders such as diabetes, but without scientific evidence, requiring more phytochemical and pharmacological studies on the plant.

AIM OF THE STUDY

This work aims to investigate the anti-hyperglycemic potential of ethanolic extracts obtained from leaves from two different accessions of Maytenus ilicifolia (MIA and MIB) in normal hyperglycemic rats.

MATERIALS AND METHODS

The animals were divided into different experimental groups: normal hyperglycemic (negative control); MIA (treatment of Maytenus ilicifolia extract from access 116); MIB (treatment with Maytenus ilicifolia extract from access 122; and glipizide (positive control). At 30 min after treatment, all animals received glucose overload orally. Blood collection occurred at different periods for the assessment of blood glucose (0, 60, 90 and 210 min after treatment) and at the end of the experiment blood was collected through cardiac puncture and the liver, muscle, pancreas and intestine were dissected for further analysis.

RESULTS

Chromatographic analysis identified oleic and palmitic acid as the most common constituents, and both extracts of Maytenus ilicifolia caused a reduction in blood glucose levels within 60 min after administration of glucose overload when compared to the normal hyperglycemic group. No significant changes were observed in hepatic and muscular glycogen levels, plasma insulin concentration and disaccharidases activity with none of the extracts in the model employed. However, hyperglycemic rats treated with the extracts showed a marked increase in triglyceride and HDL cholesterol levels.

CONCLUSIONS

Our data suggest that Maytenus ilicifolia extracts from different locations showed differences in chemical composition which did not reflect significant differences in the results of biological tests. In addition, it was possible to conclude that the treatment with Maytenus ilicifolia had a discreet anti-hyperglycemic effect; however, it was not possible to identify the responsible mechanism, being necessary, therefore, new studies using different technologies in order to determine the possible mechanisms of action of the extract.

Protective effects of medicinal plant against diabetes induced cardiac disorder: A review

ETHNOPHARMACOLOGY RELEVANCE

Nowadays, there is an increase in global tendency to use medicinal plants as preventive and therapeutic agents to manage diabetes and its long-term complications such as cardiovascular disorders owing to their availability and valuable traditional background.

AIM OF STUDY

This review aims to introduce common medicinal plants, which have been demonstrated to have cardioprotective effects on diabetes and their mechanisms of action.

MATERIALS AND METHODS

Online literature databases, including Web of Sciences, PubMed, Science Direct, Scopus and Google Scholar were searched without date limitation by May 2020. The following keywords (natural products or medicinal plants or herbal medicine or herb or extract) and (diabetes or antidiabetic or hyperglycemic) and (cardiomyopathy or heart or cardioprotective or cardiac or cardio) were used, and after excluding non-relevant articles, 81 original English articles were selected.

RESULTS

The surveyed medicinal plants induced cardioprotective effects mostly through increasing antioxidant effects leading to attenuating ROS production as well as by inhibiting inflammatory signaling pathways and related cytokines. Moreover, they ameliorated the Na+/K + ATPase pump, the L-type Ca₂⁺ channel current, and the intracellular ATP. They also reduced cardiac remodeling and myocardial cell apoptosis through degradation of caspase-3, Bax, P53 protein, enhancement of Bcl-2 protein expression as well as downregulation of TGFβ1 and TNFα expression. In addition, the extracts improved cardiac function through increasing EF% and FS% as well as restoring hemodynamic parameters.

CONCLUSIONS

The reviewed medicinal plants demonstrated cardioprotective manifestations in diabetes through intervention with mechanisms involved in the diabetic heart to restore cardiovascular complications.

Antidiabetic and Antilipidemic Activity of Root Extracts of Salacia oblonga against Streptozotocin-Induced Diabetes in Wistar Rats

Salacia oblonga is used to treat diabetes, hypocholesteremia, gonorrhea, rheumatism, asthma, inflammation, oxidative stress, etc. In the present study, the antidiabetic activity of S. oblonga methanolic root extracts collected from three geographical locations, viz., Eleshwaram (Andhra Pradesh), Thoothukudi (Tamil Nadu), and Karwar (Karnataka), was studied in vitro. Among the three extracts, S. oblonga root extracts from Eleshwaram showed maximum α-glucosidase and α-amylase inhibitory activities, indicating better antidiabetic activity. Acute toxicity studies of S. oblonga carried out in Albino Wistar rats showed no toxicity. Further, in vivo studies showed antidiabetic and antilipidemic activities in Albino Wistar rats with induced type II diabetes mellitus. Type II diabetes mellitus was induced in the experimental rats by intraperitoneal injection of nicotinamide and streptozotocin. The rats were orally fed different doses (ranging from 0 to 400 mg/kg body weight) of S. oblonga root extracts from Eleshwaram for 14 days. Blood glucose, lipid, bilirubin, and creatinine levels were analyzed on day 0, 7, and 14. The S. oblonga root extract from Eleshwaram decreased the glucose levels in a dose-dependent manner as well as the lipid, creatinine, and bilirubin levels in diabetic rats. Thus, the present study demonstrates antidiabetic and antilipidemic properties of S. oblonga root extracts.

Reduction of blood glucose by plant extracts and their use in the treatment of diabetes mellitus; discrepancies in effectiveness between animal and human studies

ETHNOPHARMACOLOGICAL RELEVANCE

The global problem of diabetes, together with the limited access of large numbers of patients to conventional antidiabetic medicines, continues to drive the search for new agents. Ancient Asian systems such as traditional Chinese medicine, Japanese Kampo medicine, and Indian Ayurvedic medicine, as well as African traditional medicine and many others have identified numerous plants reported anecdotally to treat diabetes; there are probably more than 800 such plants for which there is scientific evidence for their activity, mostly from studies using various models of diabetes in experimental animals.

AIM OF THE REVIEW

Rather than a comprehensive coverage of the literature, this article aims to identify discrepancies between findings in animal and human studies, and to highlight some of the problems in developing plant extract-based medicines that lower blood glucose in patients with diabetes, as well as to suggest potential ways forward.

METHODS

In addition to searching the 2018 PubMed literature using the terms 'extract AND blood glucose, a search of the whole literature was conducted using the terms 'plant extracts' AND 'blood glucose' AND 'diabetes' AND 'double blind' with 'clinical trials' as a filter. A third search using PubMed and Medline was undertaken for systematic reviews and meta-analyses investigating the effects of plant extracts on blood glucose/glycosylated haemoglobin in patients with relevant metabolic pathologies.

FINDINGS

Despite numerous animal studies demonstrating the effects of plant extracts on blood glucose, few randomised, double-blind, placebo-controlled trials have been conducted to confirm efficacy in treating humans with diabetes; there have been only a small number of systematic reviews with meta-analyses of clinical studies. Qualitative and quantitative discrepancies between animal and human clinical studies in some cases were marked; the factors contributing to this included variations in the products among different studies, the doses used, differences between animal models and the human disease, and the impact of concomitant therapy in patients, as well as differences in the duration of treatment, and the fact that treatment in animals may begin before or very soon after the induction of diabetes.

CONCLUSION

The potential afforded by natural products has not yet been realised in the context of treating diabetes mellitus. A systematic, coordinated, international effort is required to achieve the goal of providing anti-diabetic treatments derived from medicinal plants.

A comprehensive review on xanthone derivatives as α-glucosidase inhibitors

α-Glucosidase plays an important role in carbohydrate metabolism and is therefore an attractive therapeutic target for the treatment of diabetes, obesity and other related complications. In the last two decades, considerable interest has been given to natural and synthetic xanthone derivatives in this field of research. Herein, a comprehensive review of the literature on xanthones as inhibitors of α-glucosidase activity, their mechanism of action, experimental procedures and structure-activity relationships have been reviewed for more than 280 analogs. With this overview we intend to motivate and challenge researchers (e.g. chemistry, biology, pharmaceutical and medicinal areas) for the design of novel xanthones as multipotent drugs and exploit the properties of this class of compounds in the management of diabetic complications.

MD-1, a poly herbal formulation indicated in diabetes mellitus ameliorates glucose uptake and inhibits adipogenesis - an in vitro study

Background

Type 2 Diabetes (T2D) is a polygenic disease requiring a multipronged therapeutic approach. In the current scenario, the use of polyherbals is increasing among the diabetics. MD-1, a poly herbal formulation is constituted as a mixture of six popular anti diabetic herbs, used in the management of Diabetes mellitus (DM). The physicochemical, biochemical and in vitro efficacy studies have been carried out to ascertain the possible mechanisms underlying the anti-diabetic action of MD-1.

Methods

MD-1 was evaluated for residual toxins as per Ayurvedic Pharmacoepia of India (API) procedures. The hydro alcoholic extract of the formulation (HAEF) was evaluated for anti oxidant activity against 2, 2-diphenyl-1-picrylhydrazil (DPPH) and nitric oxide radicals in vitro. The effect of HAEF on carbohydrate digestive enzymes α-glucosidase and α-amylase was studied using biochemical assays. HAEF was studied for its glucose lowering potential in L6 myotubes and 3T3L1 preadipocytes, using 2-deoxy-D-[1-³H] glucose (2-DG) uptake assay. Effect of MD-1 on adipogenesis was evaluated in 3T3L1 adipocytes using oil O red staining. The effect of HAEF on mRNA expression of peroxisome proliferator activated receptor gamma (PPARγ) and glucose transporter 4 (GLUT4) in 3T3L1 adiocytes was investigated by reverse transcriptase polymerase chain reaction (RT-PCR). Statistical analysis was performed by student t-test, ANOVA.

Results

Residual toxins present within the API limits and HAEF demonstrated strong antioxidant potential and significantly inhibited the α-glucosidase (IC₅₀ 63.6 ± 0.46 μg/mL) and α-amylase (IC₅₀ 242.81 ± 1.26 μg/mL) activity. HAEF significantly (p < 0.05) enhanced the insulin stimulated glucose uptake in both the cell lines studied. Unlike standard pioglitazone (PGZ), HAEF modulated the mRNA expression of PPARγ and GLUT4 (p < 0.0001) in 3T3L1 adipocytes, without inducing adipogenesis.

Conclusion

Physicochemical parameters established in the study may serve as reference standards in regular quality control. Absence of residual toxins underpins the safety. The enhanced glucose uptake and favorable modulation of insulin sensitivity through a plausible weak PPARγ agonism is similar to the distinct PPARγ activation pattern of several reported natural compound agonists. The differential binding modes of such dynamic combinatorial ligands within the formulation unlike synthetic ligands like thiozolidinediones (TZD) can be linked to the safe mitigation of diabetic complications by MD-1.

Enhydrin Regulates Postprandial Hyperglycemia in Diabetic Rats by Inhibition of α-Glucosidase Activity

During the last few years, numerous attempts were made to identify effective α-glucosidase inhibitors from natural sources in order to develop new alternatives for diabetes management. Smallanthus sonchifolius (yacon) leaves were found to be effective in controlling postprandial hyperglycemia. Enhydrin, a constituent of yacon leaves, was noted for its significant hypoglycemic properties in diabetic rats. These properties were also demonstrated for yacon leaves decoction, which is rich in phenolic compounds such as chlorogenic acid and its derivatives. The purpose of the present study was to evaluate the potential of yacon leaves decoction and the isolated compound enhydrin to inhibit α-glucosidase enzyme, a possible mechanism of the above antihyperglycemic effect. In vitro assays showed that both 10% decoction and enhydrin significantly inhibited the activity of the yeast α-glucosidase enzyme in a dose-dependent manner, IC₅₀ values being 50.40 and 134.17 μg/ml, respectively. In vivo experiments showed a rapid decrease in the hyperglycemic peak after sucrose load (2 g/kg body weight) in normal rats treated with the 10% decoction (140 mg/kg) and enhydrin (0.8 mg/kg). Both treatments caused a significant decrease in blood glucose levels in diabetic rats after sucrose load compared to diabetic control. These results suggest that both products assayed could be effective in the management of postprandial hyperglycemia through inhibition of α-glucosidase in the small intestine.

Aspects of extraction and biological evaluation of naturally occurring sugar-mimicking sulfonium-ion and their synthetic analogues as potent α-glucosidase inhibitors from Salacia: a review

A review of the selective inhibitory activities of sulfonium compounds ofSalaciaagainst intestinal α-glucosidases, structural features important for effective inhibition and the toggling approach for controlling starch digestion and glucose release.

Pharmacokinetics of mangiferin and its metabolite-Norathyriol, Part 1: Systemic evaluation of hepatic first-pass effect in vitro and in vivo

Mangiferin (MGF), a glucoside of xanthone existing in phytomedicines and food, is increasingly attracting attention on diabetes treatment, while the underlying mechanism leading to its low oral bioavailability is unclear. Norathyriol (NTR), an active metabolite with hypoglycemic activity and its exposure after MGF dosing remains unclear. Hence, a rapid and sensitive LC-MS/MS method was established and validated to determine MGF and NTR and applied in the PK study in rats. Correspondingly, the in vitro experiments on temperature-dependent uptake, and MGF metabolism in hepatocyte and enterobacteria samples were performed. Results revealed that hepatic first-pass effect slightly contributed to the poor bioavailability of MGF, based on the MGF exposure in portal vein plasma was nearly similar to that in systemic plasma, and the MGF accumulation in the liver was limited, so was that of NTR. Correspondingly, the in vitro study revealed the MGF uptake was mainly dependent on poor passive transport, possibly leading to its limited hepatic metabolism and accumulation. Moreover, the NTR exposure remained considerably low (C_max  < 3 ng/mL, AUC_NTR /AUC_MGF  < 3%) in plasma after single MGF dosing, corresponding to its tiny proportion (0.1%) of MGF in MGF-incubated enterobacteria samples. However, given the low generation and elimination rates of NTR, NTR might accumulate in plasma and exert effects after repeated MGF dosing, although requires further study. This work is the first systemic study on PK profiles of MGF and NTR in vitro and in vivo, which is important for the interpretation on the poor bioavailability and pharmacodynamics of MGF. © 2016 BioFactors, 42(5):533-544, 2016.

Mangiferin modulation of metabolism and metabolic syndrome

The recent emergence of a worldwide epidemic of metabolic disorders, such as obesity and diabetes, demands effective strategy to develop nutraceuticals or pharmaceuticals to halt this trend. Natural products have long been and continue to be an attractive source of nutritional and pharmacological therapeutics. One such natural product is mangiferin (MGF), the predominant constituent of extracts of the mango plant Mangifera indica L. Reports on biological and pharmacological effects of MGF increased exponentially in recent years. MGF has documented antioxidant and anti-inflammatory effects. Recent studies indicate that it modulates multiple biological processes involved in metabolism of carbohydrates and lipids. MGF has been shown to improve metabolic abnormalities and disorders in animal models and humans. This review focuses on the recently reported biological and pharmacological effects of MGF on metabolism and metabolic disorders. © 2016 BioFactors, 42(5):492-503, 2016.

Salacia - The new multi-targeted approach in diabetics

Salacia species plant has been used traditionally as an Ayurvedic medicine for diabetes mellitus. Studies over the past decades have shown its multi-targeted role in diabetics. In the present review article, various mechanisms of action of Salacia on diabetics are discussed in detail. Apart from the well-known action of decreasing postprandial glucose sugar by inhibiting α-glucosidase and α-pancreatic amylase, it also inhibits aldose reductase which otherwise results in microvascular complications. Importantly, its peroxisome proliferator-activated receptor (PPAR)-γ agonist (such as thiazolidinediones, the insulin sensitizers) action increases the uptake of free fatty acid (FFA) and facilitates their storage in subcutaneous fat rather than the visceral fat. This reduces plasma FFA and insulin resistance. Furthermore, it increases the expression of and translocation to the cell surface of glucose transporter 1 and 4 receptors which result in glucose uptake by the liver and skeletal muscle and decreases plasma glucose levels. It also decreases inflammatory cytokines and increases adiponectin expression. Salacia as PPAR-α agonist (such as fibrates) has a role in the management of dyslipidemia. The activation of PPAR-α leads to the increased expression of lipoprotein lipase and apolipoprotein (Apo) A-V and decrease in hepatic Apo-C-III. These actions lower plasma triglycerides in chylomicrons and very low-density lipoprotein particles, thus liberating fatty acids, which are taken up and stored as fat in adipocytes. Salacia has been shown to suppress the overexpression of cardiac PPAR-α (similar to angiotensin-converting enzyme inhibitors/angiotensin receptor blockers) and thereby preventing diabetic cardiomyopathy. It also suppresses the cardiac angiotensin II Type 1 receptors resulting in antihypertrophic and antifibrogenic effect.

An Updated Review on the Phytochemistry, Pharmacology, and Clinical Trials of Salacia oblonga

Salacia oblonga (S. oblonga), a perennial herb, has been used for thousands of years in ayurvedic medicine and is closely associated with prevention, treatment, and cure of various human ailments such as obesity and diabetes. A vast and wide range of chemical compounds such as polyphenols, friedelane-type triterpenes, norfriedelane-type triterpenes, eudesmane-type sesquiterpenes including various glycosides had been isolated from this plant. This review is aimed to survey the literature covering the phytochemistry and pharmacology of S. oblonga and to review the scientific data including active components and their multi-targeted mechanisms of action against various metabolic syndromes. We also included clinical trials related to this plant in this review. The overview would assist researchers to gather scientific information related to S. oblonga in future.

Anti-diabetic and Anti-hyperlipidemic Effects and Safety of Salacia reticulata and Related Species

Extracts of Salacia reticulata Wight (Hypocrataceae) roots, stems, and leaves have been used in Asia for hundreds of years for the folkloric treatment of diabetes and other health problems. Constituents that have been identified as exhibiting anti-diabetic effects include salacinol, kotalanol, ponkorinol, salaprinol, and their corresponding de-0-sulfonated compounds. Mangiferin, kotalagenin 16-acetate and various proanthocyanidin oligomers have also been isolated. Studies indicate that Salacia extracts modulate multiple targets that influence carbohydrate and lipid metabolism including α-glucosidase, aldose reductase, pancreatic lipase, peroxisomal proliferator-activated receptor-α, glucose transporter-4 mediated glucose uptake, and angiotensin II type 1 receptor. Furthermore, Salacia extracts exhibit free radical scavenging, antioxidant and hepatoprotectant activities. In human studies, Salacia extracts have been shown to decrease plasma glucose and insulin levels, decrease HbA1c, and modulate serum lipid levels with no adverse effects being reported. Similar results have been demonstrated in rat and mouse models as well as in vitro systems. Safety of S. reticulata and other Salacia species as S. oblonga and S. chinensis in rats and mice indicate that extracts are exceedingly safe. No clinical studies have examined the effects of Salacia extracts on human weight loss, although weight loss and decreases in weight gain have been demonstrated in animal models. Because of the large number of pharmacologically active compounds, it is difficult to establish standards for extracts.

The antihyperlipidemic mechanism of high sulfate content ulvan in rats

Numerous studies have suggested that hyperlipidemia is closely linked to cardiovascular disease. The aim of this study was to investigate the possible antihyperlipidemia mechanism of HU (high sulfate content of ulvan) in high-cholesterol fed rats. Wistar rats were made hyperlipidemic by feeding with a high-cholesterol diet. HU was administered to these hyperlipidemia rats for 30 days. Lipid levels and the mRNA expressions of FXR, LXR and PPARγ in liver were measured after 30 days of treatment. In the HU-treated groups, the middle dosage group of male rats (total cholesterol (TC): p < 0.01) and the low-dosage group of female rats (TC, LDL-C: p < 0.01) showed stronger activity with respect to antihyperlipidemia. Moreover, some HU groups could upregulate the mRNA expression of FXR and PPARγ and downregulate the expression of LXR. For the male rats, compared with the hyperlipidemia group, the middle dosage HU had the most pronounced effect on increasing the mRNA levels of FXR (p < 0.01); low- and high-dosage HU showed a significant inhibition of the mRNA levels of LXR (p < 0.01). All HU female groups could upregulate the mRNA expression of PPARγ in a concentration-dependent manner. In summary, HU could improve lipid profiles through upregulation of FXR and PPARγ and downregulation of LXR.

Herbal medicines for the treatment of nonalcoholic steatohepatitis: current scenario and future prospects

Nonalcoholic steatohepatitis (NASH) is a multifactorial disease and has close correlations with other metabolic disorders. This makes its treatment difficult using a single pharmacological drug. Use of plant extract/decoction or polyherbal formulation to treat various liver diseases is very well mentioned in various traditional systems of medicine (Ayurveda, Japanese or traditional Chinese Medicine, and Kampo medicine). Medicinal herbs are known for their multifaceted implications and thus can form an effective treatment schedule against NASH. Till date, several plant extracts, polyherbal formulations, and phytochemicals have been evaluated for their possible therapeutic potential in preventing onset and progression of NASH in experimental models, but clinical studies using the same are sparse. Herbal extracts with antioxidants, antidiabetic, and antihyperlipidemic properties have been shown to ameliorate symptoms of NASH. This review article is a meticulous compilation of our current knowledge on the role of natural products in alleviating NASH and possible lacunae in research that needs to be addressed.

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.

Management of cardiorenal metabolic syndrome in diabetes mellitus: a phytotherapeutic perspective

Cardiorenal syndrome (CRS) is a complex disease in which the heart and kidney are simultaneously affected and their deleterious declining functions are reinforced in a feedback cycle, with an accelerated progression. Although the coexistence of kidney and heart failure in the same individual carries an extremely bad prognosis, the exact cause of deterioration and the pathophysiological mechanisms underlying the initiation and maintenance of the interaction are complex, multifactorial in nature, and poorly understood. Current therapy includes diuretics, natriuretic hormones, aquaretics (arginine vasopressin antagonists), vasodilators, and inotropes. However, large numbers of patients still develop intractable disease. Moreover, the development of resistance to many standard therapies, such as diuretics and inotropes, has led to an increasing movement toward utilization and development of novel therapies. Herbal and traditional natural medicines may complement or provide an alternative to prevent or delay the progression of CRS. This review provides an analysis of the possible mechanisms and the therapeutic potential of phytotherapeutic medicines for the amelioration of the progression of CRS.

Mangiferin and its aglycone, norathyriol, improve glucose metabolism by activation of AMP-activated protein kinase

CONTEXT

Mangiferin has been reported to possess antidiabetic activities. Norathyriol, a xanthone aglycone, has the same structure as mangiferin, except for a C-glucosyl bond. To our best knowledge, no study has been conducted to determine and compare those two compounds on glucose consumption in vitro.

OBJECTIVE

In this study, the effects of norathyriol and mangiferin on glucose consumption in normal and insulin resistance (IR) L6 myotubes were evaluated. Simultaneously, the potential mechanism of this effect was also investigated.

MATERIALS AND METHODS

Normal or IR L6 myotubes were incubated with norathyriol (2.5 ∼ 10 μM, 0.625 ∼ 2.5 μM), mangiferin (10 ∼ 40 μM, 2.5 ∼ 10 μM) or rosiglitazone (20 μM) and/or 0.05 nM insulin for 24 h, respectively. The glucose consumption was assessed using the glucose oxidase method. Immunoblotting was performed to detect protein kinase B (PKB/Akt) and AMP-activated protein kinase (AMPK) phosphorylation in L6 myotubes cells.

RESULTS

Norathyriol and mangiferin treatment alone increased the glucose consumption 61.9 and 56.3%, respectively, in L6 myotubes and made additional increasing with 0.05 nM insulin. In IR L6 myotubes, norathyriol treatment made increasing with or without insulin, mangiferin treatment also made increasing but only when co-treated with insulin. Immunoblotting results showed that norathyriol and mangiferin produced an increase of 1.9 - and 1.8-fold in the phosphorylation levels of the AMPK, but not in Akt.

DISCUSSION AND CONCLUSION

Our findings suggest that norathyriol and mangiferin could improve the glucose utilization and insulin sensitivity by up-regulation of the phosphorylation of AMPK. Norathyriol may be considered as an active metabolite responsible for the antidiabetic activity of mangiferin.

Modulation of hepatic sterol regulatory element-binding protein-1c-mediated gene expression contributes to Salacia oblonga root-elicited improvement of fructose-induced fatty liver in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Salacia oblonga root (SOR) is a traditionally herbal medicine for obesity and diabetes, which are closely associated with fatty liver. To investigate the molecular mechanisms of SOR in the treatment of dietary-induced fatty liver.

MATERIALS AND METHODS

Male rats were co-administered with fructose in drinking water and vehicle or the aqueous-ethanolic extract of SOR (by gavage, once daily) for 10 weeks. Biochemical variables were determined enzymatically or by ELISA. Gene expression was analyzed by Real-Time PCR and/or Western blot.

RESULTS

SOR treatment (20mg/kg) diminished fructose-induced fatty liver indicated by decreases in excess triglyceride accumulation and the increased vacuolization and Oil Red O staining area in the livers of rats. Importantly, Hepatic gene expression profile revealed that SOR suppressed fructose-stimulated overexpression of sterol regulatory element-binding protein (SREBP)-1/1c mRNA and nuclear protein. In accord, overexpression of SREBP-1c-responsive genes, such as fatty acid synthase, acetyl-CoA carboxylase-1 and stearoyl-CoA desaturase-1, was also downregulated. In contrast, overexpressed nuclear protein of carbohydrate response element binding protein and mRNA of its target gene liver pyruvate kinase were not altered. Additionally, SOR also did not affect expression of peroxisome proliferator-activated receptor-gamma- and -alpha, as well as their target genes, such as carnitine palmitoyltransferase-1a, acyl-CoA oxidase and CD36.

CONCLUSIONS

These results suggest that modulation of hepatic sterol regulatory element-binding protein-1c-mediated gene expression contributes to SOR-elicited improvement of fructose-induced fatty liver in rats. Our findings provide a better understanding of SOR in the treatment of obesity and diabetes.

Nutritional supplements and their effect on glucose control

As diabetes mellitus (DM) continues to be a growing health concern, many people have been turning to natural health products (NHPs) in order to manage this condition, adjunctive to, or even in place of conventional therapies. In order to keep up with this trend, research focussing on the efficacy and mechanisms behind the most common NHPs has been growing amongst the scientific community. The purpose of this chapter is to search and compile scientific literature focussing on the most commonly used NHPs in diabetes treatment, so to educate health professionals on the efficacy, safety and dosage of these products. From our findings, it is apparent that there are promising results from many studies on the potential benefit of NHPs in the treatment of diabetes. Nonetheless, many of the herbs and single nutraceuticals still require further studies in order to confirm safety, dosage and potential interactions with standard conventional therapies. Soluble fibre, alpha lipoic acid, milk thistle, prickly pear cactus and pycnogenol appear to be the most beneficial in the treatment of diabetes.

Herbal medicines for the management of diabetes

Herbal medicines have been used in the management of diabetes in traditional medicine. This chapter reviews recent findings of the most popular herbs reported to treat diabetes through their relevant mechanistic pathways. These include increased insulin secretion, improvement in insulin sensitivity, enhanced glucose uptake by adipose and muscle tissues, inhibition of glucose absorption from intestine, inhibition of glucose production from hepatocytes and anti-inflammatory activities. The pharmacological activities have highlighted the potential efficacy of these herbal medicines in the management of diabetes.

Rhodiola crenulata root ameliorates derangements of glucose and lipid metabolism in a rat model of the metabolic syndrome and type 2 diabetes

ETHNOPHARMACOLOGICAL RELEVANCE

Rhodiola species are traditionally used as tonics and stimulants to treat asthenia, suggesting their possible regulatory effect on energy metabolism. Clinical trials have demonstrated their glucose-lowering effect in type 2 diabetes.

AIM OF THE STUDY

To examine the effects of Rhodiola on glucose and lipid metabolism in the metabolic syndrome and type 2 diabetes.

MATERIALS AND METHODS

Zucker diabetic fatty (ZDF) rats were treated with Rhodiola crenulata root (RCR) powder (100 and 500 mg/kg, by gavage, once daily for 4 weeks). In addition, the effects of RCR on sucrose-induced acute hyperglycemia in mice and olive oil-induced hypertriglyceridemia in rats were also examined. Biochemical variables were determined enzymatically or by ELISA.

RESULTS

In ZDF rats, RCR treatment decreased the increased plasma insulin and triglyceride concentrations at baseline, the index of the homeostasis model assessment of insulin resistance (HOMA-IR) and excessive hepatic triglyceride accumulation. This treatment also inhibited abnormal increases in plasma glucose and insulin concentrations during oral glucose tolerance test. Furthermore, RCR reversed the increased adipose insulin resistance index, and accelerated the decline of plasma concentrations of non-esterified fatty acids after exogenous glucose stimulation. However, RCR minimally affected sucrose-induced acute hyperglycemia in mice and olive oil-induced acute hypertriglyceridemia in rats.

CONCLUSIONS

The present results demonstrate that RCR treatment improves metabolic derangements in animal model of the metabolic syndrome and type 2 diabetes. Our findings may provide new pharmacological basis of therapeutics for the adaptogenic plants to treat metabolic derangements-associated disorders, such as asthenia.

Salacia oblonga ameliorates hypertriglyceridemia and excessive ectopic fat accumulation in laying hens

ETHNOPHARMACOLOGICAL RELEVANCE

Salacia oblonga root (SOR) is an Ayurvedic medicine for obesity and diabetes, those are associated with glucose and lipid metabolism.

AIM OF THE STUDY

SOR has been demonstrated previously to improve glucose and lipid metabolism in animal models of obesity and diabetes and to be a peroxisome proliferator-activated receptor-alpha activator. However, the anti-obesogenic and anti-diabetic mechanisms of SOR are still not largely understood. Here, we investigated the effects of SOR on lipid metabolism using laying hen, a unique animal model with a very high rate of triglyceride synthesis in the liver.

MATERIALS AND METHODS

Laying hens and preadolescent pullets were treated with the layer ration containing 0%, 0.5%, or 1% SOR water extract for 4 weeks. Biochemical variables were determined enzymatically.

RESULTS

Laying hens showed much higher fasted triglyceride concentrations (increased by 5-13 folds) in plasma, liver, skeletal muscle and heart than pullets. 1% SOR extract treatment inhibited body weight increase without affecting food intake. Importantly, this treatment substantially attenuated hypertriglyceridemia and inhibited increases in triglyceride contents in the non-adipose tissues. However, SOR extract did not induce change in plasma glucose concentration. Moreover, SOR extract did not alter all variables in pullets.

CONCLUSIONS

These results demonstrate that SOR ameliorates hypertriglyceridemia and excessive ectopic fat accumulation in laying hens. These findings suggest that the triglyceride-lowering property is one of the primary effects of SOR, possibly via hepatic mechanisms.

The Ayurvedic Medicine Salacia oblonga Attenuates Diabetic Renal Fibrosis in Rats: Suppression of Angiotensin II/AT1 Signaling

In human diabetic nephropathy, the extent of tubulointerstitial fibrosis is the leading cause of end-stage renal disease; fibrosis is closely correlated with renal dysfunction. Although a wide array of medicinal plants play a role in the prevention and treatment of diabetes, there are few reports of the application of herbal medicines in amelioration of renal fibrosis, or the underlying mechanisms by which such benefits are mediated. The efficacy of the Ayurvedic antidiabetic medicine Salacia oblonga (SO) root on rat renal fibrosis was investigated. An aqueous extract from SO (100 mg/kg, p.o., 6 weeks) diminished renal glomerulosclerosis and interstitial fibrosis in Zucker diabetic fatty (ZDF) rats, as revealed by van Giesen-staining. SO also reduced renal salt-soluble, acid-soluble and salt-insoluble collagen contents. These changes were accompanied by normalization of hypoalbuminemia and BUN. Gene profiling revealed that the increase in transcripts encoding the glomerulosclerotic mediators collagen I, collagen IV, fibronectin, angiotensin II type 1 receptor (AT1), transforming growth factor (TGF)-β1, plasminogen activator inhibitor (PAI)-1 observed in ZDF rat kidney was suppressed by SO. In rat-derived mesangial cells, similar to the effect of the AT1 antagonist telmisartan, SO and its major component mangiferin suppressed the stimulatory effect of angiotensin II on proliferation and increased mRNA expression and/or activities of collagen I, collagen IV, fibronectin, AT1, TGF-β1 and PAI-1. Considered together the present findings demonstrate that SO attenuates diabetic renal fibrosis, at least in part by suppressing anigiotensin II/AT1 signaling. Further, it now emerges that mangiferin is an effective antifibrogenic agent.

Increased renal collagen cross-linking and lipid accumulation in nephropathy of Zucker diabetic fatty rats

BACKGROUND

Zucker diabetic fatty (ZDF) rat is a genetic model of type 2 diabetes and obesity. The mechanism underlying nephropathy in ZDF rats, however, remains unclear.

METHODS

ZDF rats were compared to age-matched Zucker lean (ZL) rats. Physiological and blood biochemical parameters, renal glomerular cross-sectional area (hematoxylin-eosin staining), fibrosis (van Giesen staining), collagen composition (Sircol Collagen Assay), lipids (enzymatic method) and mRNA expression (RT-PCR) were determined.

RESULTS

ZDF rats showed an increase in renal-insoluble collagen content and the ratio of renal-insoluble to salt-soluble collagen (2- and 1.5-fold of the control animals). There were increases in renal glomerulosclerosis and interstitial fibrosis in ZDF rats (increased to 2-fold) in the glomerular mesangium and tubulointerstitium, and increased glomerular area. Renal triglyceride accumulated to greater than 2-fold of those levels in ZL rats. These changes were accompanied by hypoalbuminemia, and elevated plasma blood urea nitrogen and uric acid levels. Gene profiling showed increased expression of transcripts encoding the glomerulosclerotic mediator collagens I and IV, plasminogen activator inhibitor-1, transforming growth factor-beta1, and angiotensin II type 1 receptor in ZDF rat kidney. Moreover, renal expression of mRNAs encoding sterol regulatory element-binding protein-1, a nuclear transcription factor that activates genes involved in fatty acid synthesis, and acetyl-CoA carboxylase, a key enzyme that mediates fatty acid synthesis, was increased in ZDF rats.

CONCLUSIONS

Our findings suggest that dysregulated gene expression may result in increased renal collagen cross-linking and lipid accumulation, that may be associated with development of nephropathy in the animal model of type 2 diabetes and obesity.

Salacia oblonga root decreases cardiac hypertrophy in Zucker diabetic fatty rats: inhibition of cardiac expression of angiotensin II type 1 receptor

AIMS

We investigated the effect of the water extract of Salacia oblonga (SOE), an ayurvedic antidiabetic and antiobesity medicine, on obesity and diabetes-associated cardiac hypertrophy and discuss the role of modulation of cardiac angiotensin II type 1 receptor (AT(1)) expression in the effect.

METHODS

SOE (100 mg/kg) was given orally to male Zucker diabetic fatty (ZDF) rats for 7 weeks. At the end-point of the treatment, the hearts and left ventricles were weighed, cardiomyocyte cross-sectional areas were measured, and cardiac gene profiles were analysed. On the other hand, angiotensin II-stimulated embryonic rat heart-derived H9c2 cells and neonatal rat cardiac fibroblasts were pretreated with SOE and one of its prominent components mangiferin (MA), respectively. Atrial natriuretic peptide (ANP) mRNA expression and protein synthesis and [(3)H]thymidine incorporation were determined.

RESULTS

SOE-treated ZDF rats showed less cardiac hypertrophy (decrease in weights of the hearts and left ventricles and reduced cardiomyocyte cross-sectional areas). SOE treatment suppressed cardiac overexpression of ANP, brain natriuretic peptide (BNP) and AT(1) mRNAs and AT(1) protein in ZDF rats. SOE (50-100 microg/ml) and MA (25 micromol) suppressed angiotensin II-induced ANP mRNA overexpression and protein synthesis in H9c2 cells. They also inhibited angiotensin II-stimulated [(3)H]thymidine incorporation by cardiac fibroblasts.

CONCLUSIONS

Our findings demonstrate that SOE decreases cardiac hypertrophy in ZDF rats, at least in part by inhibiting cardiac AT(1) overexpression. These studies provide insights into a potential cardioprotective role of a traditional herb, which supports further clinical evaluation in obesity and diabetes-associated cardiac hypertrophy.

Salacia root, a unique Ayurvedic medicine, meets multiple targets in diabetes and obesity

In many traditional schools of medicine it is claimed that a balanced modulation of several targets can provide a superior therapeutic effect and decrease in side effect profile compared to a single action from a single selective ligand, especially in the treatment of certain chronic and complex diseases, such as diabetes and obesity. Diabetes and obesity have a multi-factorial basis involving both genetic and environmental risk factors. A wide array of medicinal plants and their active constituents play a role in the prevention and treatment of diabetes. Salacia roots have been used in Ayurvedic medicine for diabetes and obesity since antiquity, and have been extensively consumed in Japan, the United States and other countries as a food supplement for the prevention of obesity and diabetes. Recent pharmacological studies have demonstrated that Salacia roots modulate multiple targets: peroxisome proliferator-activated receptor-alpha-mediated lipogenic gene transcription, angiotensin II/angiotensin II type 1 receptor, alpha-glucosidase, aldose reductase and pancreatic lipase. These multi-target actions may mainly contribute to Salacia root-induced improvement of type 2 diabetes and obesity-associated hyperglycemia, dyslipidemia and related cardiovascular complications seen in humans and rodents. The results of bioassay-guided identification indicate that mangiferin, salacinol, kotalanol and kotalagenin 16-acetate are at least in part responsible for these multi-target regulatory activities of Salacia roots. The evidence suggests that this unique traditional medicine fulfills a multiple-target strategy in the prevention and treatment of diabetes and obesity. Although toxicological studies have suggested minimal adverse effects of the herbal medicine in rodents, a clinical trial is crucial to further confirm the safety of Salacia roots. In addition, further mechanistic studies are necessary in order to allow a better understanding of how use of Salacia root may interact with other therapeutic interventions.

An aqueous extract of Salacia oblonga root, a herb-derived peroxisome proliferator-activated receptor-alpha activator, by oral gavage over 28 days induces gender-dependent hepatic hypertrophy in rats

Activation of peroxisome proliferator-activated receptor (PPAR)-alpha by natural and synthetic chemicals induces hepatic hypertrophy. An aqueous extract of Salacia oblonga root (SOW) is an Ayurvedic medicine with anti-diabetic and anti-obesity properties. In the present study, it was found that SOW (100, 300 and 900mg/kg, once daily by oral gavage over a 28 day period) elicited dose-related increases in liver weight (LW) by 1.6%, 13.4% and 42.5%, respectively, and in the ratio of LW to body weight by 8.8%, 16.7% and 40.2%, respectively, in male rats. These effects were less pronounced in females. SOW selectively increased liver mass in male rats but Sudan red staining was not different, which indicates that hepatic lipid accumulation was similar in both genders. However, SOW even at the highest dosage did not influence serum ALT and AST activities in male or female rats. Moreover, SOW was found to activate PPAR-alpha in human hepatoma-derived HepG2 cells, as evidenced by the upregulation of PPAR-alpha and acyl-CoA oxidase mRNA expression. Thus, SOW-dependent PPAR-alpha activation may precede the development of the gender difference in hepatic hypertrophy; this process may be influenced by sex hormone status.

Pomegranate flower: a unique traditional antidiabetic medicine with dual PPAR-alpha/-gamma activator properties

PPARs are transcription factors belonging to the superfamily of nuclear receptors. PPAR-alpha is involved in the regulation of fatty acid (FA) uptake and oxidation, inflammation and vascular function, while PPAR-gamma participates in FA uptake and storage, glucose homeostasis and inflammation. The PPARs are thus major regulators of lipid and glucose metabolism. Synthetic PPAR-alpha or PPAR-gamma agonists have been widely used in the treatment of dyslipidaemia, hyperglycaemia and their complications. However, they are associated with an incidence of adverse events. Given the favourable metabolic effects of both PPAR-alpha and PPAR-gamma activators, as well as their potential to modulate vascular disease, combined PPAR-alpha/-gamma activation has recently emerged as a promising concept, leading to the development of mixed PPAR-alpha/-gamma activators. However, some major side effects associated with the synthetic dual activators have been reported. It is unclear whether this is a specific effect of the particular synthetic compounds or a class effect. To date, a medication that may combine the beneficial metabolic effects of PPAR-alpha and PPAR-gamma activation with fewer undesirable side effects has not been successfully developed. Pomegranate plant parts are used traditionally for the treatment of various disorders. However, only pomegranate flower has been prescribed in Unani and Ayurvedic medicines for the treatment of diabetes. This review provides a new understanding of the dual PPAR-alpha/-gamma activator properties of pomegranate flower in the potential treatment of diabetes and its associated complications.

Mechanism of hypolipidemic effect of crocin in rats: Crocin inhibits pancreatic lipase

The hypolipidemic mechanism of crocin, an active ingredient in Gardenia jasminoides Ellis and Crocus sativus L, was examined in rats. In diet-induced hyperlipidemic rats, a 10-day treatment with crocin significantly reduced serum triglyceride, total cholesterol, low density lipoprotein (LDL) cholesterol and very low density lipoprotein (VLDL) cholesterol level in the daily dose range of 25 to 100 mg/kg. Results of the modified fat-loading method indicated that crocin inhibited the absorption of fat and cholesterol and this inhibition is closely related to the hydrolysis of fat. In addition, the modified fat-balance method demonstrated that crocin increased the fecal excretion of fat and cholesterol in rats, but had no influence on the elimination of bile acids. The results of the in situ loop method and enzyme assay indicated that crocin could not directly block the absorption of cholesterol from rat jejunum but could selectively inhibit the activity of pancreatic lipase as a competitive inhibitor. These findings suggest that crocin yielded its hypolipidemic effect by inhibiting pancreatic lipase, leading to the malabsorption of fat and cholesterol.

Leads from Indian medicinal plants with hypoglycemic potentials

Diabetes mellitus is caused due to deficiency in production of insulin by the pancreas, or by the ineffectiveness of the insulin produced. It is a global problem and number of those affected is increasing day by day. The plants provide a potential source of hypoglycemic drugs because many plants and plant derived compounds have been used in the treatment of diabetes. Several medicinal plants have found potential use as hypoglycemic in the Indian system of medicines, including ayurveda. Many Indian plants have been investigated for their beneficial use in different types of diabetes and reports occur in numerous scientific journals. This article aims to provide a comprehensive review on various plant species from Indian biosphere and their constituents, which have been shown to display potent hypoglycemic activity. The use of herbs as hypoglycemic is a major avenue in Indian perspectives particularly for treating diabetes, which require to be explored more effectively as there are so many literatures available on these aspects. This paper describes the chemistry, activity and usage of the constituents isolated from these plants from India for the treatment of diabetes.

Salacia oblonga root improves cardiac lipid metabolism in Zucker diabetic fatty rats: Modulation of cardiac PPAR-α-mediated transcription of fatty acid metabolic genes

Excess cardiac triglyceride accumulation in diabetes and obesity induces lipotoxicity, which predisposes the myocytes to death. On the other hand, increased cardiac fatty acid (FA) oxidation plays a role in the development of myocardial dysfunction in diabetes. PPAR-alpha plays an important role in maintaining homeostasis of lipid metabolism. We have previously demonstrated that the extract from Salacia oblonga root (SOE), an Ayurvedic anti-diabetic and anti-obesity medicine, improves hyperlipidemia in Zucker diabetic fatty (ZDF) rats (a genetic model of type 2 diabetes and obesity) and possesses PPAR-alpha activating properties. Here we demonstrate that chronic oral administration of SOE reduces cardiac triglyceride and FA contents and decreases the Oil red O-stained area in the myocardium of ZDF rats, which parallels the effects on plasma triglyceride and FA levels. Furthermore, the treatment suppressed cardiac overexpression of both FA transporter protein-1 mRNA and protein in ZDF rats, suggesting inhibition of increased cardiac FA uptake as the basis for decreased cardiac FA levels. Additionally, the treatment also inhibited overexpression in ZDF rat heart of PPAR-alpha mRNA and protein and carnitine palmitoyltransferase-1, acyl-CoA oxidase and 5'-AMP-activated protein kinase mRNAs and restored the downregulated acetyl-CoA carboxylase mRNA. These results suggest that SOE inhibits cardiac FA oxidation in ZDF rats. Thus, our findings suggest that improvement by SOE of excess cardiac lipid accumulation and increased cardiac FA oxidation in diabetes and obesity occurs by reduction of cardiac FA uptake, thereby modulating cardiac PPAR-alpha-mediated FA metabolic gene transcription.

Pomegranate flower extract diminishes cardiac fibrosis in Zucker diabetic fatty rats: modulation of cardiac endothelin-1 and nuclear factor-kappaB pathways

The diabetic heart shows increased fibrosis, which impairs cardiac function. Endothelin (ET)-1 and nuclear factor-kappaB (NF-kappaB) interactively regulate fibroblast growth. We have recently demonstrated that Punica granatum flower (PGF), a Unani anti-diabetic medicine, is a dual activator of peroxisome proliferator-activated receptor (PPAR)-alpha and -gamma, and improves hyperglycemia, hyperlipidemia, and fatty heart in Zucker diabetic fatty (ZDF) rat, a genetic animal model of type 2 diabetes and obesity. Here, we demonstrated that six-week treatment with PGF extract (500 mg/kg, p.o.) in Zucker diabetic fatty rats reduced the ratios of van Gieson-stained interstitial collagen deposit area to total left ventricular area and perivascular collagen deposit areas to coronary artery media area in the heart. This was accompanied by suppression of overexpressed cardiac fibronectin and collagen I and III mRNAs. Punica granatum flower extract reduced the up-regulated cardiac mRNA expression of ET-1, ETA, inhibitor-kappaBbeta and c-jun, and normalized the down-regulated mRNA expression of inhibitor-kappaBalpha in Zucker diabetic fatty rats. In vitro, Punica granatum flower extract and its components oleanolic acid, ursolic acid, and gallic acid inhibited lipopolysaccharide-induced NF-kappaB activation in macrophages. Our findings indicate that Punica granatum flower extract diminishes cardiac fibrosis in Zucker diabetic fatty rats, at least in part, by modulating cardiac ET-1 and NF-kappaB signaling.

Punica granatum flower extract, a potent alpha-glucosidase inhibitor, improves postprandial hyperglycemia in Zucker diabetic fatty rats

Postprandial hyperglycemia plays an important role in the development of type 2 diabetes and has been proposed as an independent risk factor for cardiovascular diseases. The flowering part of Punica granatum Linn. (Punicaceae) (PGF) has been recommended in Unani literature as a remedy for diabetes. We investigated the effect and action mechanism of a methanolic extract from PGF on hyperglycemia in vivo and in vitro. Oral administration of PGF extract markedly lowered plasma glucose levels in non-fasted Zucker diabetic fatty rats (a genetic model of obesity and type 2 diabetes), whereas it had little effect in the fasted animals, suggesting it affected postprandial hyperglycemia in type 2 diabetes. In support of this conclusion the extract was found to markedly inhibit the increase of plasma glucose levels after sucrose loading, but not after glucose loading in mice, and it had no effect on glucose levels in normal mice. In vitro, PGF extract demonstrated a potent inhibitory effect on alpha-glucosidase activity (IC50: 1.8 microg/ml). The inhibition is dependent on the concentration of enzyme and substrate, as well as on the length of pretreatment with the enzyme. These findings strongly suggest that PGF extract improves postprandial hyperglycemia in type 2 diabetes and obesity, at least in part, by inhibiting intestinal alpha-glucosidase activity.