Antidiabetic activity of alcoholic stem extract of Gymnema montanum in streptozotocin-induced diabetic rats

Identification of Potential Plant-Derived Pancreatic Beta-Cell-Directed Agents Using New Custom-Designed Screening Method: Gymnema sylvestre as an Example

BACKGROUND

Folk medicines are attractive therapeutic agents for treating type 2 diabetes mellitus (T2DM). Most plant extracts that have been suggested to restore β-cells function were tested in vivo. Some only have been tested in vitro to determine whether they have a direct effect on β-cells islets of Langerhans. Currently, there are no defined criteria for screening of β-cell-directed plant-based remedies as potential antidiabetic agents.

SUMMARY

In this review, we have identified certain criteria/characteristics that can be used to generate a "screening portfolio" to identify plant extracts as potential β-cell-directed agents for the treatment of T2DM. To validate our screening method, we studied the potential therapeutic efficacy of a Gymnema sylvestre (GS) extract using the screening criteria detailed in the review. Six criteria have been identified and validated using OSA®, a GS extract. By using this screening method, we show that OSA® fulfilled most of the criteria identified for an effective β-cell-directed antidiabetic therapy, being an effective insulin-releasing agent at nontoxic concentrations; maintaining β-cell insulin content by stimulating a concomitant increase in insulin gene transcription; maintaining β-cell mass by protecting against apoptosis; and being effective at maintaining normoglycemia in vivo in a mouse model and a human cohort with T2DM.

KEY MESSAGES

The present review has highlighted the importance of having a screening portfolio for plant extracts that have potential antidiabetic effects in the treatment of T2DM. We propose that this screening method should be adopted for future studies to identify new β-cell-directed antidiabetic plant derived agents.

In Vivo Hypolipidemic, Hypoglycemic, Antihyperglycemic, and In Vitro Antioxidant Effects of Podocarpus gracilis Leaf Extract and Fractions in Diabetic Mice

Background

Podocarpus gracilis is an evergreen, dioecious tree found in Ethiopia and other African nations. It can reach a height of 60 meters. Without any scientific validation, ethnobotanical studies conducted in Ethiopia revealed that the Podocarpus gracilis plant's leaf is consumed orally to treat diabetes mellitus. Hence, this study aims to evaluate the in vivo blood glucose level lowering, lipid-lowering, and in vitro-free radical scavenging responses of Podocarpus gracilis leaf extract and fractions on experimental mice induced with diabetes.

Methods

The in vitro antioxidant activity of PGC (Podocarpus gracilis) leaf extract was assessed by using a diphenyl-2-picrylhydrazyl (DPPH) assay. The oral glucose-loaded, normoglycemic, and streptozotocin- (STZ-) induced diabetic mouse models were employed. In the STZ-induced mice model, the leaf extract and solvent fractions activity on serum lipid and weight were also measured. The extract and fractions were tested at 100, 200, and 400 mg/kg dosages. One-way ANOVA was used to determine the statistical significance of BGL (blood glucose level) changes within and between groups, and Tukey's post hoc multiple comparisons were then performed.

Results

In the acute toxicity study of Podocarpus gracilis leaf extract and fractions, there was no evidence of animal mortality at the maximum dose of 2 g/kg during the observation period. The extract-treated group with normoglycemia revealed a significant lowering in BGL at the 4-hour mark of 27.4% (p < 0.001) and 25.2% (p < 0.01) at doses of 200 mg/kg and 400 mg/kg, respectively, compared to that in negative control. In the oral glucose tolerance test (OGTT) model, only 400 mg/kg treated groups at 120 min after exposure showed a BGL reduction of 31.17% which was statistically significant (p < 0.05) in comparison to the negative control. In the single-dose STZ-induced model, eighth-hour BGL measurements from CE 100, CE 200, CE 400, and GLC5 showed drops in BGL of 43.1%, 44.1%, 45%, and 47.3% from baseline fasting BGL values. In the repeated streptozotocin (STZ)-induced model, at all doses of leaf extract and fractions, the fasting BGL was significantly (p < 0.001) reduced. Moreover, the leaf extract and solvent fractions have shown a significant (p < 0.001) reduction of serum lipids such as LDL, TC, and VLDL, and at the same time, it increases HDL at 14 days with body weight gained. In the test for antioxidant activity, the half-maximal inhibitory concentrations (IC50) for leaf extract and the standard medication (ascorbic acid) were 8.2 μg/ml and 3.3 μg/ml, respectively. The IC50 value denotes the concentration of the sample required to scavenge 50% DPPH radicals.

Conclusion

The 80% hydromethanolic leaf extract and fractions of Podocarpus gracilis exhibited blood glucose lowering, lipid-lowering activity in normoglycemic, oral glucose tolerance test (OGTT) mode, and STZ-induced diabetic mice with weight gains. There is scientific support for the alleged traditional use as an antidiabetic, lipid-lowering, and antioxidant activity. The results need to be confirmed by future studies.

Evaluation of Antidiabetic Effect of Luteolin in STZ Induced Diabetic Rats: Molecular Docking, Molecular Dynamics, In Vitro and In Vivo Studies

Despite the existence of modern antidiabetic medications, diabetes still affects millions of individuals worldwide, with a high death and disability rate. There has been a concerted search for alternative natural medicinal agents; luteolin (LUT), a polyphenolic molecule, might be a good choice, both because of its efficacy and because of it having fewer side effects, compared to conventional medicines. This study aims to explore the antidiabetic potential of LUT in diabetic rats, induced by streptozotocin (STZ; 50 mg/kg b.w.), intraperitoneally. The level of blood glucose, oral glucose tolerance test (OGTT), body weight, glycated hemoglobin A1c (HbA1c), lipidemic status, antioxidant enzymes, and cytokines were assessed. Also, its action mechanism was explored through molecular docking and molecular dynamics simulations. Oral supplementation of LUT for 21 days resulted in a significant decrease in the blood glucose, oxidative stress, and proinflammatory cytokine levels, and modulated the hyperlipidemia profile. LUT also ameliorated the tested biomarkers of liver and kidney function. In addition, LUT markedly reversed the damage to the pancreas, liver, and kidney cells. Moreover, molecular docking and molecular dynamics simulations revealed excellent antidiabetic behavior of LUT. In conclusion, the current investigation revealed that LUT possesses antidiabetic activity, through the reversing of hyperlipidemia, oxidative stress, and proinflammatory status in diabetic groups. Therefore, LUT might be a good remedy for the management or treatment of diabetes.

Evaluation of in vivo Antidiabetic, Antidyslipidemic and in vitro Anti-Oxidant Activity of Extract and Solvent Fractions of Discopodium penninervum Hoschst Leaf in Mice: Normoglycemic and Streptozocin-Induced Model

BACKGROUND

Diabetes mellitus has become a huge global public health and economic issue. The shortcomings of current medicines, as well as their serious side effects, prompted a focused quest for natural medicinal agents. In Ethiopia, the leaf of Discopodium penninervum Hoschst has been utilized in the traditional health system to treat diabetes. The goal of this study was to confirm the anti-diabetic, anti-dyslipidemia, and anti-oxidant activity of Discopodium penninervum Hoschst leaf in both in vitro and in vivo.

METHODS

In the normoglycemic, glucose-loaded, and streptozotocin-induced diabetic mouse models, the blood glucose-lowering effects of extract and solvent fractions of the leaf of Discopodium penninervum Hoschst were tested. The weight and lipid profile of streptozotocin-induced diabetic mice were assessed after treatment with leaf extract and solvent fractions for 14 days. The DPPH test was used to assess the antioxidant activity of the plant leaf extract.

RESULTS

In the normoglycemic model and glucose loaded test, the leaf extract of Discopodium penninervum Hoschst demonstrated significant blood glucose decrease (34.1%, p<0.001) and 44.5%, p<0.001, respectively, when compared to the normal control. When compared to a diabetic control group, extract and solvent fractions significantly (p<0.001) reduced blood glucose levels on the 14th day in the streptozotocin-induced diabetic model. In addition, serum TC, STG, TG, LDL, and VLDL levels were reduced significantly (p<0.001). IC50 values of leaf extract and a standard medication (ascorbic acid) in the antioxidant activity test were 4.1g/mL and 10.23g/mL, respectively.

CONCLUSION

The hydro-alcoholic leaf extract and solvent fractions of Discopodium penninervum Hoschst leaves have demonstrated blood glucose-lowering effect, which justify ethnobotanical use, and can therefore be used as a good insight for new anti-diabetic medication source with a call for additional studies.

Assessment of antidiabetic potential of Musa acuminata peel extract and its fractions in experimental animals and characterisation of its bioactive compounds by HPTLC

Musa acuminata is a rich source of nutritional food with acclaimed therapeutic uses. Banana pulp has been reported to possess antidiabetic properties. The present study aimed to investigate antidiabetic potential of Musa acuminata peels and its fractions along with diabetic complications. Animals were divided into various groups (n = 6), EMA 100, 200 and 400 mg/kg/day and various fractions 50 and 100 mg/kg/day along with vehicle administered orally to alloxan-induced diabetic rats (n = 6) for 21 days for extract and for 7 days for fractions. Musa acuminata possess antidiabetic potential by reducing plasma glucose by utilising glucose in the periphery and production of hepatic glycogen and further reduce protein catabolism which is responsible for improvement in body weight along with reduction in diabetic complications such as dyslipidemia, peripheral neuropathy and nephropathy. Protective role of Musa acuminata in treatment of diabetes and its complications.

Recent developments made in the assessment of the antidiabetic potential of gymnema species - From 2016 to 2020

BACKGROUND

In traditional herbal medicine, the Gymnema species has been well known for various therapeutic activities such as anti-diabetic, anti-inflammatory, anti-bacterial, anti-arthritic, anti-hyperlipidemic, cytotoxic, and immunostimulatory activities. This review is an effort to analyse all the recent studies done to explore the anti-diabetic potential of traditional Gymnema species. Gymnema sylvestre (Retz.) R.Br. ex Sm. is an important member of the Apocynaceae family that has been used to treat a variety of diseases, the most studied of which is diabetes. This action is mostly due to the pharmacologically active phytoconstituents present in its extract, which include gymnemic acids, triterpenoid saponin glycosides, and so on. Numerous other Gymnema species have also demonstrated a similar pharmacological action.

INTRODUCTION

The goal of this study is to give a critical overview of the available data on Gymnema species that are used to treat diabetes. The major goal of this study is to give up-to-date knowledge on ethnopharmacology, botany, pharmacology, and structure-activity relationships of Gymnemaspecies from 2016 to 2020, as well as potential future research. The potential of using medicinal plants for alleviating symptoms of diabetes is recently being recognized. This review aims to summarize the available data and highlight both the potential and shortcomings of using Gymnema therapeutically. This knowledge can further be used to develop more therapeutically effective drugs derived from Gymnema.

MATERIALS AND METHODS

Data for Gymnema species was obtained using a mix of several search terms from online databases such as PubMed, SCOPUS, and Europe PMC. Other literature surveys relevant to traditional knowledge, phytochemistry, pharmacology, or structure-activity relationship activity were also used as reference. Several methods by which Gymnema species extracts exert their effects have been investigated, and a summary of the newly discovered chemicals isolated from the plant in the previous five years has been provided.

RESULTS

SAR based evaluation has been carried out for a total of 27 pharmacologically active compounds belonging to three species of Gymnema genus (Gymnema sylvestre, Gymnema latifolium, and Gymnema inodorum).These compounds demonstrated the critical significance of plant medicines for diabetes management. Numerous heterocyclic compounds have anti-diabetic action and may serve as a starting point for the design and identification of new diabetes inhibitors.

CONCLUSIONS

This study aims to provide researchers with a better understanding of the antidiabetic potential Gymnema species, as well as an outline of prospective future developments. It was concluded after studying the evaluation done in the last 5 years that although extracts of Gymnema have shown good antidiabetic potential, further modifications in the structures could result in the development of more potent and safer compounds.

Amelioration of diabetes and its complications by Manilkara zapota (L) P. Royen fruit peel extract and its fractions in alloxan and STZ-NA induced diabetes in Wistar rats

Purpose

This study aims to evaluate the effects of Manilkara zapota (L) P. Royen fruit peel extract (EMZFP) and its fractions in ameliorating diabetes and its complications in alloxan and STZ-NA induced diabetes in Wistar rats.

Methods

Antidiabetic effects of EMZFP were assessed in alloxan (150 mg kg^-1) induced diabetes in differently grouped rats (n=6). Diabetic rats were treated with EMZFP 150, 300, and 600 mg kg^-1 while, glimepiride (0.09 mg kg^-1) was used as a reference standard. Treated animals were assessed for various biological parameters i.e. blood glucose, serum lipids, nephroprotective markers, cardiovascular risk indices, liver glycogen, neuropathy, body weight, and histopathology of kidneys. However, for evaluating antidiabetic effects of fractions (chloroform, acetone, ethyl acetate, and remaining ethanol fraction) of EMZFP, diabetes was induced by streptozotocin (60 mg kg^-1)-nicotinamide (120 mg kg^-1/ml) in differently grouped male rats (n=6). Diabetic rats were treated with EMZFP fractions 200 mg kg^-1 however; glibenclamide (10 mg kg^-1) was a reference standard and evaluated for blood glucose, serum lipids, cardiovascular risk indices, and diabetic neuropathy.

Results

EMZFP 300 and 600 mg kg^-1/day demonstrated significant antihyperglycemic effects with augmentation in glycogen content, perfection in serum lipid profile, cardiovascular risk indices, body weight enhancement, nephroprotective effects, beneficial in peripheral neuropathy, and histopathological evidence of reversal of glomerulosclerosis. EMZFP-Et and EMZFP-EA fractions depicted a significant improvement in blood glucose, serum lipid profile, cardiovascular risk indices, and peripheral neuropathy.

Conclusion

EMZFP and its Et and EA fractions ameliorated diabetes and its complications by improving glycemic control and associated biochemical alteration.

Highlights

• Manilkara Zapota (L.) P. Royen fruit peel 70% ethanolic extract exert antidiabetic effects• EMZFP significantly ameliorated diabetic biochemical parameters and its complications.• EMZFP-Et and EMZFP-EA fractions exert potential antihyperglycemic, hypolipidemic effects and significantly improved cardiovascular risk indices, and peripheral neuropathy.• Studied MZFP can be used as promising natural herbal source of antidiabetic principles.

Evidence from a Systematic Review and Meta-Analysis Pointing to the Antidiabetic Effect of Polyphenol-Rich Plant Extracts from Gymnema montanum, Momordica charantia and Moringa oleifera

In vitro and animal model studies are of great interest for selecting new phytochemicals, including polyphenols with antioxidative properties, as candidates for antidiabetic drugs. This review provides evidence from a critical literature data analysis on the effects of plant extract supplementation in diabetes mellitus management. We considered and meta-analyzed the efficacy of oral supplementation of plant extracts in animal model studies and examined physiological and oxidative stress parameters. Finally, 23 articles were included in the meta-analysis, revealing three plants with experimentally confirmed in vivo and in vitro antidiabetic properties: Gymnema montanum, Momordica charantia and Moringa oleifera. The following parameter changes resulted from an investigation of the supplementation: reduced oxidative stress, decreased insulin resistance, increased insulin release, reduced adiposity, and a modulatory effect on glycolysis and gluconeogenesis, as well as attenuation of diabetes-associated weight loss, reduced fasting blood glucose and lowered oxidative status. A comparison of Gymnema montanum versus Glybenclamide revealed the superiority of extracts over drug administration in some aspects. Although the analyzed extracts are promising candidates for antidiabetic treatment, there is much inconsistent data in the literature. Therefore, ultimate references for using these compounds in the prevention of diabetes are currently not applicable.

In vivo hypoglycemic, antihyperglycemic and antidyslipidemic effects of the solvent fractions of Hagenia abyssinica leaves in mice

Background

Hagenia abyssinica leaves have been used traditionally for the management of different diseases including diabetes mellitus (DM) although the antidiabetic effect of different solvent fractions of hydromethanol H. abyssinica leaf extract has not been scientifically studied. Thus, this study was conducted to investigate the in vivo hypoglycemic, antihyperglycemic and antidyslipidemic effects of the solvent fractions of Hagenia abyssinica leaf extract.

Methods

The antidiabetic effect of the solvent fractions was evaluated in normal, oral glucose loaded and streptozotocin-induced diabetic mice. Hypoglycemic, antihyperglycemic, antidyslipidemic activities and effect on body weight change were evaluated after administration of three different doses of the solvent fractions (100, 200, and 400 mg/kg). One-way ANOVA followed by Tukey's post hoc test was used for data analysis, and p<0.05 was considered as statistically significant.

Results

The crude hydromethanol extract of H. abyssinica leaves did not show any sign of toxicity at the dose of 2000 mg/kg in mice. In normoglycemic mice, both aqueous and ethyl acetate fractions of H. abyssinica leaves showed significant (P<0.05) hypoglycemic activity. In oral glucose loaded mice, the two doses of the aqueous fraction, 200 mg/kg (p<0.05) and 400 mg/kg (p<0.001), showed a significant antihyperglycemic effect at 60 and 120 minute post-oral glucose loading while the ethyl acetate fraction showed significant antihyperglycemic effect at 60 (P<0.05 for 200 mg/kg and P<0.001 for 400 mg/kg) and 120 min (P<0.01 for 400 mg/kg) post-oral glucose loading. In single dose-treated diabetic mice, all doses of the solvent fractions caused a significant (P<0.05) reduction in blood glucose level except 100 mg/kg of the aqueous and chloroform fractions. Additionally, repeated daily treatment with the aqueous fraction significantly reduced hyperglycemia, body weight loss, and improved dyslipidemia of diabetic mice.

Conclusion

This study has revealed that the solvent fractions of H. abyssinica leaves possess in vivo blood-glucose-lowering activities on normal, oral glucose loaded, and streptozotocin-induced diabetic mice. Additionally, the aqueous fraction prevented diabetic body weight loss and dyslipidemia in mice after repeated daily dose administration.

Possible Synergistic Antidiabetic Effects of Quantified Artemisia judaica Extract and Glyburide in Streptozotocin-Induced Diabetic Rats via Restoration of PPAR-α mRNA Expression

Simple Summary

A considerable number of diabetic patients are in favour of using oral antidiabetic drugs in combination with certain herbs instead of using oral antidiabetic drugs alone. Artemisia judaica (AJ) is one of the herbs documented to have antidiabetic effects. This study examined the effect of using combination of A. judaica extract (AJE) and the oral hypoglycemic drug glyburide (GLB, 5 mg/kg) on diabetic rats. Fasting blood glucose (FBG), insulin levels, glycated hemoglobin (HbA1c) percentage, serum lipid profile, and oxidative stress biomarkers were estimated. The histopathological examination of the pancreas and the immunohistochemical analysis of anti-insulin, anti-glucagon, and anti-somatostatin protein expressions were also performed. The analysis of the hepatic mRNA expression of peroxisome proliferator-activated receptor α (PPAR-α) and nuclear factor erythroid 2-related factor-2 (Nrf2) genes was performed using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Combination of GLB and 500 mg/kg of AJE highly improved FBG, insulin levels, HbA1c, and lipid profile in blood when compared with GLB monotherapy. Furthermore, GLB plus 500 mg/kg of AJE combination was the most successful in restoring insulin content in the β-cells and diminished the levels of glucagon and somatostatin of the α- and δ-endocrine cells in the pancreatic islets, restoring PPAR-α and Nrf2 mRNA expression in the liver. In conclusion, these data indicate that GLB plus 500 mg/kg of AJE combination gives greater glycemic improvement than GLB monotherapy.

Abstract

Several members of the genus Artemisia are used in both Western and African traditional medicine for the control of diabetes. A considerable number of diabetic patients switch to using oral antidiabetic drugs in combination with certain herbs instead of using oral antidiabetic drugs alone. This study examined the effect of Artemisia judaica extract (AJE) on the antidiabetic activity of glyburide (GLB) in streptozotocin (STZ)-induced diabetes. Forty-two male Wistar rats were divided into seven equal groups. Normal rats of the first group were treated with the vehicle. The diabetic rats in the second–fifth groups received vehicle, GLB (5 mg/kg), AJE low dose (250 mg/kg), and AJE high dose (500 mg/kg), respectively. Groups sixth–seventh were treated with combinations of GLB plus the lower dose of AJE and GLB plus the higher dose of AJE, respectively. All administrations were done orally for eight weeks. Fasting blood glucose (FBG) and insulin levels, glycated hemoglobin (HbA1c) percentage, serum lipid profile, and biomarkers of oxidative stress were estimated. The histopathological examination of the pancreas and the immunohistochemical analysis of anti-insulin, anti-glucagon, and anti-somatostatin protein expressions were also performed. The analysis of the hepatic mRNA expression of PPAR-α and Nrf2 genes were performed using quantitative RT-PCR. All treatments significantly lowered FBG levels when compared with the STZ-control group with the highest percentage reduction exhibited by the GLB plus AJE high dose combination. This combination highly improved insulin levels, HbA1c, and lipid profile in blood of diabetic rats compared to GLB monotherapy. In addition, all medicaments restored insulin content in the β-cells and diminished the levels of glucagon and somatostatin of the α- and δ-endocrine cells in the pancreatic islets. Furthermore, the GLB plus AJE high dose combination was the most successful in restoring PPAR-α and Nrf2 mRNA expression in the liver. In conclusion, these data indicate that the GLB plus AJE high dose combination gives greater glycemic improvement in male Wistar rats than GLB monotherapy.

Evaluation of the Antidiabetic Potential of Extracts of Urtica dioica, Apium graveolens, and Zingiber officinale in Mice, Zebrafish, and Pancreatic β-Cell

Medicinal plants are commonly used in the treatment of diabetes, particularly as they contain flavonoids and phenolic compounds. The present study aims to investigate the activities of a polyherbal formulation made from Urtica dioica, Apium graveolens, and Zingiber officinale (UAZ) against streptozotocin–nicotinamide ((STZ-NA)-induced type 2 diabetes in CD1 mice, glucose-induced type 2 diabetes (T2DM) in zebrafish, and high glucose-induced damage in RINm5F pancreatic β-cells. In fasting mice, plasma glucose, glycosylated hemoglobin (HbA1C), lipid hydroperoxides (LOOH), thiobarbituric acid reactive substances (TBARS), and lipid profiles were significantly increased, whereas insulin, enzymatic antioxidants, and carbohydrate metabolic enzymes were altered significantly in diabetic mice. Zebrafish had similar glucose levels, liver enzymes, and lipid profiles compared to mice. The study investigated the effects of the extract in enhancing cell viability, insulin secretion, and reducing lipid peroxidation and intracellular reactive oxygen species (ROS) levels in RINm5F cells damaged by high glucose. All the above biochemical parameters were enhanced in both mice and zebrafish treated; the combined extract UAZ normalized all the biochemical parameters. The medicinal plant extracts, used either separately or in combination, ameliorated the adverse effect of glucose on cell viability and functionality of beta-RINm5F cells.

Phytochemical Screening and Antidiabetic, Antihyperlipidemic, and Antioxidant Effects of Leptopus Cordifolius Decne. In Diabetic Mice

Plants are well known in traditional herbal medicines for their hypoglycemic and hypolipidemic activities and are often used due to their accessibility, affordability, and corollary effects. Leptopus cordifolius has been reported to control diabetes in folkloric medicine, but no known scientific research has been conducted to assess the plausibility of this assertion. Therefore, the current study is aimed to investigate the antidiabetic and hypolipidemic effects of Leptopus cordifolius leaves in alloxan-induced diabetic mice. The antidiabetic and antihyperlipidemic evaluation was conducted in Swiss albino mice at doses of 150-250°mg/kg for 15°days. The blood glucose, total cholesterol, triglyceride, LDL, HDL, creatinine, ALP, SGPT, and SGOT levels were estimated according to standard procedures. Phytochemicals of leaves were analyzed using GC-MS analysis. Enzymatic antioxidant activity of the plant was investigated spectrophotometrically by carrying out superoxide dismutase, peroxidase, and catalase assays. The membrane stabilization potential of L. cordifolius leaf extracts was carried out using an in vitro haemolytic assay. The results revealed a dose response effect with the methanolic extract of L. cordifolius which had significant antihyperglycemic effects at 150-250°mg/kg in alloxan treated mice, although less than the positive control (glibenclamide). Hyperlipidemic activity was significant at 250 mg/kg. The biochemical parameters, such as total cholesterol, triglyceride, LDL, HDL, creatinine, ALP, SGPT, and SGOT, were significantly improved (p < 0.01) by the methanolic extract of 250 mg/kg compared to the diabetic group. Treatment for 15 days showed significant elevation (p < 0.01) of antioxidant enzymes. GC-MS analysis provided tentative identifications of 52 compounds in the methanolic extract of L. cordifolius, of which 12 compounds have reported antidiabetic activity. In conclusion, methanolic extract of L. cordifolius of 150 and 250°mg/kg body weight showed significant antidiabetic and antihyperlipidemic activities in alloxan-induced diabetic mice and, with further work, has the potential to be used to manage blood glucose and cholesterol levels.

Inhibitory effects of Gymnema inodorum (Lour.) Decne leaf extracts and its triterpene saponin on carbohydrate digestion and intestinal glucose absorption

ETHNOPHARMACOLOGICAL RELEVANCE

Chiang-Da, Gymnema inodorum (Lour.) Decne. (GI), is an ethnomedicinal plant that has been used for diabetic treatment since ancient times. One of the anti-diabetic mechanisms is possibly related to the actions of triterpene glycoside, (3β, 16β)-16,28-dihydroxyolean-12-en-3-yl-O-β-D-glucopyranosyl-β-D-glucopyranosiduronic acid (GIA1) in decreasing carbohydrate digestive enzymes and intestinal glucose absorption in the gut system.

AIMS OF THE STUDY

To observe the amount of GIA1 in GI leaf extracts obtained from different ethanol concentrations and to investigate the anti-hyperglycemic mechanisms of the extracts and GIA1.

MATERIALS AND METHODS

The crude extracts were prepared using 50%v/v to 95%v/v ethanol solutions and used for GIA1 isolation. The anti-hyperglycemic models included in our study examined the inhibitory activities of α-amylase/α-glucosidase and intestinal glucose absorption related to sodium glucose cotransporter type 1 (SGLT1) using Caco-2 cells.

RESULTS

GIA1 was found about 8%w/w to 18%w/w in the GI extract depending on ethanol concentrations. The GI extracts and GIA1 showed less inhibitory activities on α-amylase. The extracts from 75%v/v and 95%v/v ethanol and GIA1 significantly delayed the glycemic absorption by lowering α-glucosidase activity and glucose transportation of SGLT1. However, the 50%v/v ethanolic extract markedly decreased the α-glucosidase activity than the SGLT1 function.

CONCLUSION

Differences in the GIA1 contents and anti-glycemic properties of the GI leaf extract was dependent on ethanol concentrations. Furthermore, the inhibitory effects of the 75%v/v and 95%v/v ethanolic extracts on α-glucosidase and SGLT1 were relevant to GIA1 content.

Evaluation of in vitro and in vivo Anti-Diabetic, Anti-Hyperlipidemic and Anti-Oxidant Activity of Flower Crude Extract and Solvent Fractions of Hagenia Abyssinica (Rosaceae)

BACKGROUND

The flower of Hagenia abyssinica (Rosaceae) has been used in traditional health systems to treat diabetes mellitus in Ethiopia and Tanzania. However, the antidiabetic activity of this medicinal plant is not scientifically validated and authenticated. The present study aimed to investigate the in vitro and in vivo anti-diabetic activity of flower crude extract and solvent fractions of Hagenia abyssinica.

METHODS

The in vitro α-amylase inhibition and antioxidant activity of the crude extract and solvent fractions of Hagenia abyssinica were evaluated by using 3,5-dinitrosalicylic acid (DNSA) and diphenyl-2-picrylhydrazyl (DPPH) assay model, respectively. Blood glucose lowering activity of 80% methanolic flower crude extract and solvent fraction was studied in four animal models: normoglycemic mice model, oral glucose loaded mice model, single dose-treated streptozotocin-induced diabetic mice model, and repeated dose-treated streptozotocin-induced diabetic mice model. The effect of the crude extract and solvent fraction of Hagenia abyssinica on diabetic lipid profile and body weight was also studied.

RESULTS

The acute toxicity study of Hagenia abyssinica flower extract did not show mortality in the animals at the limit dose of 2g/kg during the observation period. The result of α-amylase enzyme inhibition activity was found in a dose-dependent manner, the strongest activity was shown by ethyl acetate fraction (54.23% inhibition at 800 μg/mL) compared to the standard acarbose having 91.87% inhibition at 800 μg/mL. Among these extracts, the crude extract had the highest antioxidant activity (58.38% inhibition at 500 μg/mL). The crude extract of H. abyssinica showed significant blood glucose-lowering effect on normoglycemic mice and oral glucose loaded mice. In streptozotocin-induced diabetic mice model, the crude extract and ethyl acetate fraction significantly decreased the fasting blood glucose level after 14 days of treatment. There were significant reductions in serum total cholesterol, serum triglycerides, very low-density lipoprotein, and low-density lipoprotein. However, there were significant increments in body weight and high-density lipoprotein as compared to untreated diabetic mice.

CONCLUSION

The result demonstrated the beneficial biochemical effects of Hagenia abyssinica extract by inhibiting α-amylase, scavenging diphenyl-2-picrylhydrazyl (DPPH) and improving serum lipid profile levels. The flower crude extract and solvent fractions of Hagenia abyssinica are effective in lowering blood glucose levels in diabetic and normoglycemic mice. The claimed traditional use as antidiabetic has scientific ground.

Evaluation of Antidiabetic Effect of Ethanolic Leaves Extract of Becium grandiflorum Lam. (Lamiaceae) in Streptozotocin-Induced Diabetic Mice

BACKGROUND

Becium grandiflorum has been used traditionally for treatment of different ailments including diabetes mellitus although it lacks scientific evidence. Thus, the present study was aimed at evaluating the antidiabetic effect of Becium grandiflorum in streptozotocin (STZ)-induced diabetic mice.

METHODS

The antidiabetic activity of hydro-ethanolic (30:70) leaf extract of Becium grandiflorum was evaluated in STZ (45 mg/kg)-induced diabetic and normal mice. Antihyperglycemic, hypoglycemic, oral glucose tolerance and body weight change effects of the extract were assessed after administering three doses of the extract (200, 400 and 600 mg/kg), glibenclamide 5 mg/kg (reference drug) and 2% Tween 80 (vehicle). One-way analysis of variance and Tukey's post hoc test were used for data analysis.

RESULTS

All doses of the extract (200 mg/kg (p<0.05), 400 mg/kg (p<0.05) and 600 mg/kg (p<0.01)) and glibenclamide 5 mg/kg (p<0.001) showed statistically significant blood glucose level reduction in normal mice as compared to Tween 80. The hydroalcoholic extract at a dose of 200 mg/kg (p<0.05), 400 mg/kg (p<0.01) and 600 mg/kg (p<0.001) showed better blood glucose tolerance after 60, 120 and 180-minute treatment duration in normal mice as compared to negative control. In diabetic mice, Becium grandiflorum doses and the reference drug caused maximum reduction in blood glucose level at the end of the 15th day of treatment by 17.61%, 22.52%, 24.62% and 34.12%, respectively. The extract's doses and the standard drug showed significant (p<0.05) improvement in body weight while the diabetic control continued to lose their body weight.

CONCLUSION

Thus, Becium grandiflorum exhibits antihyperglycemic activity in STZ-induced diabetic mice, and shows improvement in oral glucose tolerance and body weight, which justifies the claimed use of the plant in ameliorating diabetes mellitus in Ethiopian folk medicine.

Oleanane hemiacetal glycosides from Gymnema latifolium and their inhibitory effects on protein tyrosine phosphatase 1B

Gymnema sylvestre (Retz.) R. Br. ex Schult. has a long history to be used as an antidiabetic herbal medicine. Various varieties of G. sylvestre, have been studied intensively on their 3β-hydroxy oleanane triterpenoid composition for hypoglycemic effects. It is also well-known that most species belonging to the same genus have similar chemical composition and biological activity. Thus, an extract of the Gymnema latifolium Wall. ex Wight, which showed considerable protein tyrosine phosphatase 1B (PTP1B) inhibitory activity (>70% inhibition at 30 μg/mL), was studied intensively. Extensive chemical investigation on the 70% EtOH of G. latifolium led to the isolation of four previously undescribed oleanane hemiacetal glycosides, gymlatinosides GL1-GL4, three previously undescribed oleanane glycosides, gymlatinosides GL5-GL7, and two known 3β-hydroxy oleanane analogs. The structures of the previously undescribed compounds were elucidated using diverse spectroscopic methods. The hemiacetal structure of the glycoside portion was further elaborated precisely by HMBC and J resolved proton NMR. Gymlatinosides GL2 and GL3 showed considerable PTP1B inhibitory effect.

Antidiabetic and Antihyperlipidemic Activities of the Leaf Latex Extract of Aloe megalacantha Baker (Aloaceae) in Streptozotocin-Induced Diabetic Model

BACKGROUND

Diabetes mellitus has become a major public health and economic problem across the globe. The inadequacies, as well as serious adverse effects associated with conventional medicines, led to a determined search for alternative natural therapeutic agents. The leaf latex extract of Aloe megalacantha has been used for the management of diabetes mellitus in Ethiopian folk medicine. This study aimed to evaluate the antidiabetic and antihyperlipidemic effects of the leaf latex extract of A. megalacantha in streptozotocin- (STZ-) induced diabetic model.

METHODS

The experimental diabetes was induced in Swiss albino mice by the administration of a single dose of STZ (150 mg/kg), intraperitoneally. The leaf latex extract of A. megalacantha at three different doses (100, 200, and 400 mg/kg) was administered for a period of 14 days. Fasting blood glucose levels (BGLs) were measured by glucose-oxidase and peroxidase reactive strips. After fourteen days, mice from all groups fasted and the blood was collected through puncturing the retroorbit of the eyes under mild anesthetic condition. The collected blood sample was used to determine serum biochemical parameters such as total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and high-density lipoprotein (HDL) cholesterol. The statistical analysis of results was carried out using one-way analysis (ANOVA) followed by post hoc multiple comparison tests.

RESULTS

Oral administration of A. megalacantha leaf latex extract at doses of 100, 200, and 400 mg/kg daily for 14 days results in a significant (p < 0.05) decrease in fasting BGL as compared to negative control STZ-induced diabetic mice. The leaf latex has significantly reduced the level of TC, TG, and LDL, VLDL cholesterol while a significant (p < 0.05) HDL cholesterol increment was observed.

CONCLUSIONS

The findings of the present investigation indicated that the leaf latex of A. megalacantha possessed significant antihyperglycemic and antihyperlipidemic potential which may prove the claimed use of the plant in amelioration of diabetes and associated complications in Ethiopian folk medicine.

Ficus recemosa bark extract attenuates diabetic complications and oxidative stress in STZ-induced diabetic rats

Context Ficus recemosa Linn. (Moraceae) has been reported as a natural folk medicine with diverse pathological activities such as antioxidant, antidiabetic, renoprotective and cardioprotective. Objective The present study evaluates the preventive effect of standardised ethanol extract of F. racemosa stem bark (EEFSB) on diabetic cardiomyopathy (DC) and diabetic nephropathy (DN). Materials and methods Animals were rendered diabetic by one time administration of STZ (45 mg kg(-1), i.v.) and, after 7 d, diabetic rats were randomised into four groups of eight rats each. EEFSB (200 and 400 mg kg(-1)) was administered to diabetic rats once daily for 8 weeks. Furthermore, the presence of phytochemicals was evaluated by HPTLC. Results Treatment with EEFSB markedly restores the blood glucose and lipid level (p < 0.001), also reduced creatinine kinase (p < 0.001), lactate dehydrogenase (p < 0.001), C-reactive protein (p < 0.001), creatinine (p < 0.001), blood urea nitrogen (p < 0.001), collagen (p < 0.05) and albumin (p < 0.001) levels. Reduced level of sodium (p < 0.001), creatinine (p < 0.001), albumin (p < 0.001) and malondialdehyde (p < 0.01) in heart and kidney tissue along with enhanced activities of superoxide dismutase (p < 0.001) and reduced glutathione (p < 0.001). Moreover, left ventricular hypertrophic index and cardiac hypertrophic index were markedly reduced by EEFSB treatment. Conclusion The findings of this study provided strong scientific evidence for the traditional use of F. racemosa and postulate protective effects against diabetes and its complications such as DC and DN.

Beneficial protective effects of 2-allyl amino 4-methyl sulfanyl butyric acid on glucose metabolism and glycoprotein components in streptozotocin induced diabetic rats with molecular modeling

In the present study, the potential effects of 2-allyl amino 4-methyl sulfanyl butyric acid (AMSB) on the glucose metabolism and glycoprotein components in streptozotocin (STZ) induced experimental diabetic rats were determined. Further, molecular modeling was performed to investigate the modes of AMSB interaction with insulin receptor active sites. The blood glucose and plasma insulin levels were measured in the STZ induced diabetic rats, whereas the glucose metabolism and glycoprotein components were analyzed from the plasma and tissues. After oral treatment of AMSB there was a significant reduction in blood glucose, glucose-6-phosphatase, fructose-1,6-bisphosphatase and glycogen phosphorylase. On the other hand, the activity of the glycoprotein levels, such as hexose, hexosamine, fucose and sialic acid, were significantly reduced. In addition, a significant elevation in plasma insulin, hexokinase, glycogen and glycogen synthase were also observed in the AMSB treated rats. The molecular modeling study revealed that AMSB has a stable binding pattern to the active site of insulin, with a Gscore value of -7.34 Kcal mol^-1. From this study we conclude that AMSB has a potent antidiabetic activity in addition to its protective effect on glycoprotein metabolism.

Antioxidant, antidiabetic and hypolipidemic effects of Tulbaghia violacea Harv. (wild garlic) rhizome methanolic extract in a diabetic rat model

Background

The prevalence of diabetes mellitus (DM) continues to rise alarmingly despite years of intensive research. The need to explore alternative remedies such as traditional phytotherapy has therefore become increasingly important in the management and treatment of DM.

Methods

Diabetes was induced by a single intraperitoneal (i.p) injection of streptozotocin (40 mg/kg.b.w) in male Wistar rats. The rats were divided into 5 groups as follows: non-diabetic control fed distilled water, diabetic control fed distilled water, diabetic group treated with Tulbaghia violacea (TVL) (60 mg/kg.b.w), diabetic group treated with TVL (120 mg/kg.b.w), and diabetic group treated with glibenclamide (10 mg/kg.b.w). Food and water intake, as well as urine output were measured daily, whilst body weight and fasting blood glucose were monitored weekly. On day 42, an oral glucose tolerance test was performed on all groups. After 7 weeks, the animals were sacrificed by halothane overdose, blood was removed by cardiac puncture and tissues were harvested. Assays were performed for the determination of plasma insulin, liver glycogen content, lipid peroxidation, antioxidant enzyme levels, plasma nitric oxide levels and serum lipid and liver enzyme levels.

Results and Discussion

TVL treatment improved body weights, significantly reduced fasting blood glucose levels, improved glucose tolerance and significantly increased plasma insulin and liver glycogen content. TVL treatment also reduced liver thiobarbituric acid reactive substances (TBARS) levels, increased liver superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) and increased plasma nitric oxide (NO) levels. Furthermore, TVL administration reduced serum triglycerides, VLDL, total-cholesterol levels and increased HDL-cholesterol levels. TVL also reduced serum levels of liver enzymes, alanine aminotransferase (ALT) and aspartate aminotransferase (AST).

Conclusion

Data obtained in this study demonstrated the hypoglycemic, antioxidant, hepatoprotective and hypolipidemic effects of TVL in STZ-induced diabetic rats.

Potential anticancer properties of bioactive compounds of Gymnema sylvestre and its biofunctionalized silver nanoparticles

BACKGROUND

Gymnema sylvestre is an ethno-pharmacologically important medicinal plant used in many polyherbal formulations for its potential health benefits. Silver nanoparticles (SNPs) were biofunctionalized using aqueous leaf extracts of G. sylvestre. The anticancer properties of the bioactive compounds and the biofunctionalized SNPs were compared using the HT29 human adenoma colon cancer cell line.

METHODS

The preliminary phytochemical screening for bioactive compounds from aqueous extracts revealed the presence of alkaloids, triterpenes, flavonoids, steroids, and saponins. Biofunctionalized SNPs were synthesized using silver nitrate and characterized by ultraviolet-visible spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy, and X-ray diffraction for size and shape. The characterized biofunctionalized G. sylvestre were tested for its in vitro anticancer activity against HT29 human colon adenocarcinoma cells.

RESULTS

The biofunctionlized G. sylvestre SNPs showed the surface plasmon resonance band at 430 nm. The scanning electron microscopy images showed the presence of spherical nanoparticles of various sizes, which were further determined using the Scherrer equation. In vitro cytotoxic activity of the biofunctionalized green-synthesized SNPs (GSNPs) indicated that the sensitivity of HT29 human colon adenocarcinoma cells for cytotoxic drugs is higher than that of Vero cell line for the same cytotoxic agents and also higher than the bioactive compound of the aqueous extract.

CONCLUSION

Our results show that the anticancer properties of the bioactive compounds of G. sylvestre can be enhanced through biofunctionalizing the SNPs using the bioactive compounds present in the plant extract without compromising their medicinal properties.

β-Caryophyllene, a natural sesquiterpene, modulates carbohydrate metabolism in streptozotocin-induced diabetic rats

The study was designed to evaluate the antihyperglycemic effects of β-caryophyllene (BCP), a natural sesquiterpene from spices on streptozotocin (STZ) induced diabetic rats. Diabetes mellitus was induced by a single intraperitoneal injection of STZ (40 mg/kg b.w.) in adult male Wistar rats. Diabetic rats exhibited an increase in glucose and HbA1c with a significant fall in insulin and hemoglobin levels. Aberrations in carbohydrate metabolic enzymes were noticed in liver, kidney and skeletal muscle of diabetic rats. A fall in liver and skeletal muscle glycogen with alterations in glycogen synthase and phosphorylase activities was also observed. Oral administration of BCP in dose dependent manner and glibenclamide (600 μg/kg b.w.), a standard oral hypoglycemic drug to diabetic rats for 45 days significantly decreased glucose with increased plasma insulin levels and ameliorated the altered activities of carbohydrate metabolic enzymes to near normal. The insulinotropic effect of BCP was supported by immunohistochemical studies. BCP at a dose of 200mg/kg b.w. exerted significant antidiabetic effects than other two doses (100 and 400mg/kg b.w.). We conclude that administration of BCP has beneficial effects in glucose homeostasis in diabetic rats.

Modulatory effects of morin on hyperglycemia by attenuating the hepatic key enzymes of carbohydrate metabolism and β-cell function in streptozotocin-induced diabetic rats

The present study was aimed to evaluate the effect of morin on blood glucose, insulin level, hepatic glucose regulating enzyme activities and glycogen level in experimental diabetes. Diabetes mellitus was induced by a single intraperitoneal injection of streptozotocin (STZ) (50 mg/kg b.w.). Five days after STZ injection, diabetic rats received morin (25 and 50 mg/kg b.w.) orally for 30 days. Glibenclamide was used as reference drug. Morin treatment significantly reduced the blood glucose and improved the serum insulin levels. Further, a dose-dependent reduction in glucose-6-phosphatase and fructose-1,6-bisphosphatase was observed along with the increase in liver hexokinase and glucose-6-phosphate dehydrogenase activities. Morin supplement were found to be effective in preserving the normal histological appearance of pancreatic islets as well as to preserve insulin-positive β-cells in STZ-rats. Therefore, these findings suggest that morin displays beneficial effects in the treatment of diabetes, mediated through the regulation of carbohydrate metabolic enzyme activities.

Hypoglycemic Activity and Antioxidative Stress of Extracts and Corymbiferin from Swertia bimaculata In Vitro and In Vivo

The present study was to investigate the anti-diabetic activities of Swertia bimaculata. Based on the glucose consumption of S. bimaculata extractsand different fractions (petroleum, dichloromethane, ethyl acetate, n-butanol and water extracts) in 3T3-L1 adipocyte assay, ethanol (ETH) and dichloromethane (DTH) extracts had the most effective potency. Furthermore, ETH, DTH and corymbiferin (the most abundant component of DTH) were evaluated for anti-diabetic effects in high fat and sucrose fed combined with low dose streptozocin induced diabetic rats. DTH and corymbiferin displayed remarkable anti-diabetic activities. The fasting blood glucose levels were significantly decreased, while the serum insulin levels were obviously increased. The oral glucose tolerance was also improved. The lowed serum total cholesterol, low density lipoprotein (LDL) and triglyceride levels and increased ratio of HDL (high density lipoprotein)/LDL were observed. The insulin sensitivity was improved on the basis of increased expressions of insulin-receptor substrate-2, phosphatidylinositol 3-kinase and Ser/Thr kinase AKT2. And also DTH and corymbiferin improved antioxidant capacity and carbohydrate metabolism in diabetic rats, along with the improvement of histopathology of livers and pancreatic β cells. Corymbiferin was one of active constituents, responsible for anti-diabetic properties. Therefore, S. bimaculata could be considered as an alternative agent against diabetes mellitus.