Anti-diabetic activity of the semi-purified fractions of Averrhoa bilimbi in high fat diet fed-streptozotocin-induced diabetic rats

Edible wild plants, chicory and purslane, alleviated diabetic testicular dysfunction, and insulin resistance via suppression 8OHdg and oxidative stress in rats

Testicular dysfunction is a prevalent health problem frequently reported in individuals with diabetes mellitus (DM). Oxidative-inflammatory reactions, hormonal and spermatic abnormalities often accompany this illness. Herbal remedies "particularly wild plants" including chicory (Chicorium Intybus) and purslane (Portulaca Oleracea) are emerging as popular agents for people dealing with these issues due to their ability to act as antioxidants, reduce inflammation, and exhibit antidiabetic effects. According to the collected data, the daily administration of chicory (Ch) seed-extract (250 mg/kg) or purslane (Pu) seed-extract (200 mg/kg) to streptozotocin (STZ)-induced diabetic rats (50 mg/kg) for 30 days resulted in the normalization of fasting blood glucose (FBG), serum fructosamine, insulin levels, and insulin resistance (HOMA-IR), as well as reducing lipid peroxidation end-product malondialdehyde (MDA) level, aldehyde oxidase (AO) and xanthene oxidase (XO) activities. While caused a considerable improvement in glutathione (GSH) content, superoxide dismutase (SOD), catalase (CAT) activity, and total antioxidant capacity (TAC) when compared to diabetic rats. Ch and Pu extracts had a substantial impact on testicular parameters including sperm characterization, testosterone level, vimentin expression along with improvements in body and testis weight. They also mitigated hyperlipidemia by reducing total lipids (TL), total cholesterol (TC) levels, and low-density lipoprotein cholesterol (LDL-C), while increasing high-density lipoprotein cholesterol (HDL-C). Furthermore, oral administration of either Ch or Pu notably attuned the elevated proinflammatory cytokines as tumor necrotic factor (TNF-α), C-reactive protein (CRP), and Interleukin-6 (IL-6) together with reducing apoptosis and DNA damage. This was achieved through the suppression of DNA-fragmentation marker 8OHdG, triggering of caspase-3 immuno-expression, and elevation of Bcl-2 protein. The histological studies provided evidence supporting the preventive effects of Ch and Pu against DM-induced testicular dysfunction. In conclusion, Ch and Pu seed-extracts mitigate testicular impairment during DM due to their antihyperglycemic, antilipidemic, antioxidant, anti-inflammatory, and antiapoptotic properties.

Pharmacological and Clinical Efficacy of Picrorhiza kurroa and Its Secondary Metabolites: A Comprehensive Review

Traditional remedies for the treatment of various ailments are gaining popularity. Traditionally, one of the most valuable therapeutic herbs has been Picrorhiza kurroa Royle ex Benth. Traditional and folk uses of P. kurroa include chronic constipation, skin-related problems, burning sensation, chronic reoccurring fever, jaundice, heart problems, breathing, digestion, allergy, tuberculosis, blood-related problems, prediabetes and obesity, laxative, cholagogue, and liver stimulatory. Phytoconstituents such as glycosides, alkaloids, cucurbitacins, iridoids, phenolics, and terpenes in P. kurroa have shown promising pharmacological potential. In order to uncover novel compounds that may cure chronic illnesses, such as cardiovascular, diabetes, cancer, respiratory, and hepatoprotective diseases, the screening of P. kurroa is essential. This study comprehensively evaluated the ethnopharmacological efficacy, phytochemistry, pharmacological activity, dose, and toxicity of P. kurroa. This review provides comprehensive insights into this traditional medication for future research and therapeutic application. The purpose of this review article was to determine the pharmacological effects of P. kurroa on a variety of disorders. P. kurroa may be a natural alternative to the standard treatment for eradicating newly evolving diseases. This study is intended as a resource for future fundamental and clinical investigations.

Fat regulatory mechanisms of pine nut oil based on protein interaction network analysis

BACKGROUND

Pine nut oil (PNO), a standardized and well-defined extract of Pinus koraiensis (Korean pine), has beneficial effects on wound healing, inflammatory diseases, and cancer. However, the explanation for the mechanism by which PNO reduces body fat remains uncertain. We performed a protein-protein interaction network (PPIN) analysis to explore the genes associated with pinolenic acid using the MEDILINE database from PubChem and PubMed. It was concluded through the PPIN analysis that PNO was involved in a neutral lipid biosynthetic process.

PURPOSE

This study evaluated the effects of PNO predicted by the network analysis of fat accumulation in chronic obesity mouse models established by feeding a high fat diet (HFD) to C57BL/6J mice and explored potential mechanisms.

METHODS

HFD mice were fed only HFD or HFD with PNO at 822 and 1644 mg/kg. After an oral administration of 7 weeks, several body weight and body fat-related parameters were examined, including the following: adipose weight, adipocyte size, serum lipid profiles, adipocyte expression of PPAR-γ, sterol regulatory element binding protein (SREBP)-1c, lipoprotein lipase (LPL) and leptin.

RESULTS

We showed that oral administration of PNO to HFD mice reduces body fat weight, fat in tissue, white adipose tissue weight, and adipocyte size. The serum cholesterol was improved in the HFD mice treated with PNO. Additionally, PNO has significantly attenuated the HFD-induced changes in the adipose tissue expression of PPAR-γ, SREBP-1c, LPL, and leptin.

CONCLUSIONS

The findings from this study based on the PPIN analysis suggest that PNO has potential as drug to reduce body fat through fat regulatory mechanisms by PPAR-γ and SREBP-1c.

Contributions from Mexican Flora for the Treatment of Diabetes Mellitus: Molecules of Psacalium decompositum (A. Gray) H. Rob & Brettell

Diabetes mellitus (DM) is cited as a serious worldwide health problem that occupies second place in causes of annual mortality in Mexico. Among Mexican flora, nearly 300 plant species have been employed as hypoglycemic in popular use. Thus, their study entertains great relevance In this context, this work contributes a clear and timely review of the plant species utilized in Traditional Mexican Medicine and experimental biological models in which not only have the hypoglycemic properties of the extracts and the isolated compounds been considered, but also the anti-inflammatory and antioxidant properties, taking into account an integral focus based on the complex mechanisms involved in the pathogenesis and physiopathology of DM. Among the species reviewed, we highlight Psacalium decompositum (Asteraceae), due to the potent hypoglycemic, anti-inflammatory, and antioxidant activity of the sesquiterpenes identified as majority compounds isolated from the root, such as cacalol and cacalone that also possess the capacity of increasing insulin levels. In this manner, the present manuscript attempts to contribute necessary information for the future study of bioactive molecules that are useful in the treatment of DM, as well as also being a contribution to the knowledge and diffusion of Mexican Traditional Medicine.

Toxicity and antidiabetic activity of ethanolic extract of Sphagneticola trilobata (L.) Pruski flower in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Plants are the source of medication for preventive, curative, protective or promotive purposes. Medicinal plants are an important source for generating of novel phytomedicine. They provide profound therapeutic benefits, more affordable treatments, effectiveness, less side effects and relatively low cost or less expensive and globally competitive. Using plant derived medicine is also relatively safe compared to synthetic medicines. Many plants have proved to successfully aid in the treatment of ailments including Sphagneticola triolobata (L.) Pruski.

AIM OF STUDY

This study was therefore, designed to investigate acute and subacute toxicities, antidiabetic activity and also antioxidant activity of flower extract from S. triolobata (L.) Pruski.

METHODS

This research investigates the toxicity and antidiabetic activity of Sphagnelicola trilobata (L.) Pruski flower ethanolic extract in rats. Acute toxicity was determined by a single oral administration of S. trilobata extract of 1500, 2000, and 2500 mg/kg body weight; and subacute toxicity by oral administration every two days for 14 days. Signs of toxicity and mortality were observed during 24 h and for 14 days. Hematological values and blood chemistry were also characterized. The antidiabetic activity was examined by orally administering S. trilobata extract of 250 mg/kg body weight to streptozotocin-induced diabetic rats on a daily basis for eight weeks; and the body weight, blood glucose, serum insulin, and lipid profiles were determined. The antioxidant activity of the extract was assessed by 1, 1-diphenyl-2-picryl-hydrazyl free radical scavenging assay.

RESULTS AND CONCLUSION

The results demonstrated a median lethal dose (LD₅₀) greater than 2500 mg/kg since there was no sign of toxicity and mortality in acute and subacute toxicity testing. The high LD₅₀ indicated that S. trilobata flower ethanolic extract is safe for treatment of diabetes. There was no significant change in the body weight, hematological values, and blood chemistry of treated rats, compared with the control group. The diabetes-induced rats showed a significant reduction in blood glucose and triglyceride (p < 0.05). Meanwhile, the antioxidant activity of S. trilobata extract was lower than that of standard ascorbic acid.

Caveolin-3 protects diabetic hearts from acute myocardial infarction/reperfusion injury through β2AR, cAMP/PKA, and BDNF/TrkB signaling pathways

Diabetes mellitus (DM) might increase the incidence and mortality of cardiac failure after acute myocardial infarction (AMI) in patients. We attempted to investigate whether Caveolin-3 showed beneficial effects in DM patient post-MI injury through the cAMP/PKA and BDNF/TrkB signaling pathways. The activity of ADRB2 and cAMP/PKA signaling were impaired in nondiabetic ischemia-reperfusion (I/R) group compared with the sham and DM groups and were more impaired in diabetic I/R group than in the I/R group. In H9C2 cells, high-glucose (HG) stimulation further enhanced H/R injury by promoting cell apoptosis, inhibiting cell viability, and suppressing TrkB and Akt signaling; in contrast, the ADRB2 agonist isoprenaline (ISO) significantly attenuated the above-described effects of HG stimulation. Caveolin-3 overexpression promoted the localization of ADRB2 on the membrane of the HG-stimulated H9C2 cells, subsequently inhibiting apoptosis and promoting cell viability. Under HG stimulation, Caveolin-3 overexpression enhanced the activity of the cAMP/PKA and BDNF/TrkB signaling pathways, whereas ADRB2 silencing reversed the effects of Caveolin-3 overexpression. In conclusion, ADRB2 agonist promoted the activity of the BDNF/TrkB and cAMP/PKA signaling pathways, mitigating the HG-aggravated H/R injuries in H9C2 cells. Caveolin-3 exerts a protective effect on diabetic hearts against I/R damage through the β2AR, cAMP/PKA, and BDNF/TrkB signaling pathways.

A new prospective on the role of melatonin in diabetes and its complications

Melatonin is a hormone secreted by the pineal gland under the control of the circadian rhythm, and is released in the dark and suppressed during the day. In the past decades, melatonin has been considered to be used in the treatment for diabetes mellitus (DM). This is due to a functional inter-relationship between melatonin and insulin. Elevated oxidative stress is a feature found in DM associated with diabetic neuropathy (DN), retinopathy (DR), nephropathy and cardiovascular disease. Reactive oxygen species (ROS) and nitrogen oxidative species (NOS) are usually produced in massive amounts via glucose and lipid peroxidation, and this leads to diabetic complications. At the molecular level, ROS causes damage to the biomolecules and triggers apoptosis. Melatonin, as an antioxidant and a free radical scavenger, ameliorates oxidative stress caused by ROS and NOS. Besides that, melatonin administration is proven to bring other anti-DM effects such as reducing cellular apoptosis and promoting the production of antioxidants.

Pyridostigmine regulates glucose metabolism and mitochondrial homeostasis to reduce myocardial vulnerability to injury in diabetic mice

Diabetic patients are more susceptible to myocardial ischemia damage than nondiabetic patients, with worse clinical outcomes and greater mortality. The mechanism may be related to glucose metabolism, mitochondrial homeostasis, and oxidative stress. Pyridostigmine may improve vagal activity to protect cardiac function in cardiovascular diseases. Researchers have not determined whether pyridostigmine regulates glucose metabolism and mitochondrial homeostasis to reduce myocardial vulnerability to injury in diabetic mice. In the present study, autonomic imbalance, myocardial damage, mitochondrial dysfunction, and oxidative stress were exacerbated in isoproterenol-stimulated diabetic mice, revealing the myocardial vulnerability of diabetic mice to injury compared with mice with diabetes or exposed to isoproterenol alone. Compared with normal mice, the expression of glucose transporters (GLUT)1/4 phosphofructokinase (PFK) FB3, and pyruvate kinase isoform (PKM) was decreased in diabetic mice, but increased in isoproterenol-stimulated normal mice. Following exposure to isoproterenol, the expression of (GLUT)1/4 phosphofructokinase (PFK) FB3, and PKM decreased in diabetic mice compared with normal mice. The downregulation of SIRT3/AMPK and IRS-1/Akt in isoproterenol-stimulated diabetic mice was exacerbated compared with that in diabetic mice or isoproterenol-stimulated normal mice. Pyridostigmine improved vagus activity, increased GLUT1/4, PFKFB3, and PKM expression, and ameliorated mitochondrial dysfunction and oxidative stress to reduce myocardial damage in isoproterenol-stimulated diabetic mice. Based on these results, it was found that pyridostigmine may reduce myocardial vulnerability to injury via the SIRT3/AMPK and IRS-1/Akt pathways in diabetic mice with isoproterenol-induced myocardial damage. This study may provide a potential therapeutic target for myocardial damage in diabetic patients.

Antidiabetic, Antihyperlipidemic, Antioxidant, Anti-inflammatory Activities of Ethanolic Seed Extract of Annona reticulata L. in Streptozotocin Induced Diabetic Rats

Annona reticulata L. (Bullock's heart) is a pantropic tree commonly known as custard apple, which is used therapeutically for a variety of maladies. The present research was carried out to evaluate the possible protective effects of Annona reticulata L. (A. reticulata) ethanolic seed extract on an experimentally induced type 2 diabetes rat model. Male Albino Wistar rats were randomly divided into five groups with six animals in each group viz., control rats in group I, diabetic rats in group II, diabetic rats with 50 and 100 mg/kg/bw of ethanolic seed extract of A. reticulata in groups III and IV, respectively, and diabetic rats with metformin in group V. Treatment was given for 42 consecutive days through oral route by oro-gastric gavage. Administration of A. reticulata seed extract to diabetes rats significantly restored the alterations in the levels of body weight, food and water intake, fasting blood glucose (FBG), insulin levels, insulin sensitivity, HbA1c, HOMA-IR, islet area and insulin positive cells. Furthermore, A. reticulata significantly decreased the levels of triglycerides, cholesterol, LDL, and significantly increased the HDL in diabetic rats. A. reticulata effectively ameliorated the enzymatic (ALT, AST, ALP, GGT) and modification of histopathological changes in diabetic rats. The serum levels of the BUN, creatinine levels, uric acid, urine volume, and urinary protein were significantly declined with a significant elevation in CCr in diabetic rats treated with A. reticulata. MDA and NO levels were significantly reduced with an enhancement in SOD, CAT, and GPx antioxidant enzyme activities in the kidney, liver, and pancreas of diabetic rats treated with A. reticulata. Diabetic rats treated with A. reticulata have shown up-regulation in mRNA expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2), NAD(P)H:quinone oxidoreductase 1 (NQO1), Heme oxygenase-1 (HO-1) and protein expression level of Nrf2 with diminution in Keap1 mRNA expression level in pancreas, kidney, and liver. From the outcome of the current results, it can be inferred that seed extract of A. reticulata exhibits a protective effect in diabetic rats through its anti-diabetic, anti-hyperlipidemic, antioxidant and anti-inflammatory effects and could be considered as a promising treatment therapy in the treatment of diabetes mellitus.

Role of medicinal plants in the management of diabetes mellitus: a review

Medicinal plants have a vast potential in the treatment of various ailments due to the presence of therapeutically important phytochemicals. Diabetes is a serious metabolic disorder and several marketed medications are available to alleviate the symptoms of diabetes. However, these over the counter drugs are expensive and associated with several complications. Herbal medicines are gaining importance as they are cost-effective and also display improved therapeutic effects with lesser side effects. The present review includes the reports available on medicinal plants used for treating diabetes complications. The aim of the review is to categorize and summarize the available information on medicinal plants with anti-diabetic properties and suggesting outlooks for future research. A systematic search was performed on medicinal plants with anti-diabetic properties using several search engines such as Google Scholar, PubMed, Science Direct and other online journals and books. All the plants listed in this review are native to Asian countries and are routinely used by the traditional practitioners for the treatment of various ailments. Based on the literature data available, a total of 81 medicinal plants with anti-diabetic, anti-hyperglycemic, hypoglycemic, anti-lipidemic and insulin mimetic properties have been compiled in this review. This review provides useful information about the different medicinal plants for treating diabetes-associated complications. Further research can be carried out to study the active constituents and mechanism of these plants.

Stability of a type 2 diabetes rat model induced by high-fat diet feeding with low-dose streptozotocin injection

OBJECTIVE

The present study aims at determining the stability of a popular type 2 diabetes rat model induced by a high-fat diet combined with a low-dose streptozotocin injection.

METHODS

Wistar rats were fed with a high-fat diet for 8 weeks followed by a one-time injection of 25 or 35 mg/kg streptozotocin to induce type 2 diabetes. Then the diabetic rats were fed with regular diet/high-fat diet for 4 weeks. Changes in biochemical parameters were monitored during the 4 weeks.

RESULTS

All the rats developed more severe dyslipidemia and hepatic dysfunction after streptozotocin injection. The features of 35 mg/kg streptozotocin rats more resembled type 1 diabetes with decreased body weight and blood insulin. Rats with 25 mg/kg streptozotocin followed by normal diet feeding showed normalized blood glucose level and pancreatic structure, indicating that normal diet might help recovery from certain symptoms of type 2 diabetes. In comparison, diabetic rats fed with high-fat diet presented decreased but relatively stable blood glucose level, and this was significantly higher than that of the control group (P<0.05).

CONCLUSIONS

This model easily recovers with normal diet feeding. A high-fat diet is suggested as the background diet in future pharmacological studies using this model.

Antiradical and Xanthine Oxidase Inhibitory Activity Evaluations of Averrhoa bilimbi L. Leaves and Tentative Identification of Bioactive Constituents through LC-QTOF-MS/MS and Molecular Docking Approach

The objective of the present study was to investigate the antiradical and xanthine oxidase inhibitory effects of Averrhoa bilimbi leaves. Hence, crude methanolic leaves extract and its resultant fractions, namely hexane, chloroform, and n-butanol were evaluated for 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effect and xanthine oxidase inhibitory activity. The active constituents were tentatively identified through LC-QTOF-MS/MS and molecular docking approaches. The n-butanol fraction of A. bilimbi crude methanolic leaves extract displayed significant DPPH radical scavenging effect with IC₅₀ (4.14 ± 0.21 μg/mL) (p < 0.05), as well as xanthine oxidase inhibitory activity with IC₅₀ (64.84 ± 3.93 μg/mL) (p < 0.05). Afzelechin 3-O-alpha-l-rhamnopyranoside and cucumerin A were tentatively identified as possible metabolites that contribute to the antioxidant activity of the n-butanol fraction.

Effects of Resveratrol and Mangiferin on PPARγ and FALDH Gene Expressions in Adipose Tissue of Streptozotocin-Nicotinamide-Induced Diabetes in Rats

Type 2 diabetes (T2D) is characterized by insufficient insulin secretion by the pancreatic beta cells and insulin resistance in liver, skeletal muscle, and white adipose tissue. Adipose tissue plays a major role in glucose homeostasis and lipid metabolism. Dietary antioxidants such as resveratrol and mangiferin may offer some protection against the early stage of diabetes mellitus. Therefore, an attempt has been made to investigate the effects of resveratrol and mangiferin on biochemical parameters and molecular mechanism of PPARγ and FALDH gene expression in adipose tissue of streptozotocin- (STZ-) nicotinamide- (NA-) induced diabetic rats. Albino Wister rats were randomly divided into five groups: control rats (Group 1), diabetic control rats (Group 2), diabetic rats given resveratrol (40 mg/kg body weight per day; Group 3), diabetic rats given mangiferin (40 mg/kg body weight per day; Group 4), diabetic rats given glibenclamide (0.6 mg/kg body weight per day; Group 5). Serum biochemical parameters-total cholesterol (TC), total triglyceride (TG), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, glycosylated hemoglobin (HbA1c), urea, and uric acid were analyzed. We found that the oral administration of resveratrol and mangiferin to STZ-NA-induced diabetic rats for 30 days showed the significant protective effect on all the biochemical parameters. A significant reduction in blood glucose and HbA1c levels was observed in rats treated with 40 mg/kg body weight per day of resveratrol or mangiferin. Moreover, both these antioxidants showed significant enhancement of PPARγ and FALDH gene expression in rat adipose tissue compared to control rats.

Discovery of pancreastatin inhibitor PSTi8 for the treatment of insulin resistance and diabetes: studies in rodent models of diabetes mellitus

Pancreastatin (PST) is an endogenous peptide which regulates glucose and lipid metabolism in liver and adipose tissues. In type 2 diabetic patients, PST level is high and plays a crucial role in the negative regulation of insulin sensitivity. Novel therapeutic agents are needed to treat the diabetes and insulin resistance (IR) against the PST action. In this regard, we have investigated the PST inhibitor peptide-8 (PSTi8) action against diabetogenic PST. PSTi8 rescued PST-induced IR in HepG2 and 3T3L1 cells. PSTi8 increases the GLUT4 translocation to cell surface to promote glucose uptake in L6-GLUT4myc cells. PSTi8 treatment showed an increase in insulin sensitivity in db/db, high fat and fructose fed streptozotocin (STZ) induced IR mice. PSTi8 improved the glucose homeostasis which is comparable to metformin in diabetic mice, characterized by elevated glucose clearance, enhanced glycogenesis, enhanced glycolysis and reduced gluconeogenesis. PST and PSTi8 both were docked to the GRP78 inhibitor binding site in protein-protein docking, GRP78 expression and its ATPase activity studies. The mechanism of action of PSTi8 may be mediated by activating IRS1/2-phosphatidylinositol-3-kinase-AKT (FoxO1, Srebp-1c) signaling pathway. The discovery of PSTi8 provides a promising therapeutic agent for the treatment of metabolic diseases mainly diabetes.

Myrtenal alleviates hyperglycaemia, hyperlipidaemia and improves pancreatic insulin level in STZ-induced diabetic rats

CONTEXT

Myrtenal is monoterpene a constituent of essential oils found mainly in herbs such as mint, pepper, cumin, etc. It exerts admirable pharmacological activities against many diseases including diabetes. Hyperlipidaemia is a secondary complication of diabetes and also a major risk factor for cardiovascular diseases.

OBJECTIVE

The present study investigated the possible antihyperlipidaemic efficacy of myrtenal on plasma glucose, pancreatic insulin, plasma and tissue lipid levels in streptozotocin (STZ) induced diabetic rats.

MATERIALS AND METHODS

Diabetes was induced in male Wistar rats by a single intraperitoneal injection of STZ (40 mg/kg b.w.). Myrtenal (80 mg/kg) was administered orally to diabetic rats for a period of 28 d. Plasma glucose, pancreatic insulin, TC, TGs, FFAs, PLs, LDL-C, HDL-C, VLDL, atherogenic index, (HMG-CoA) reductase, LPL, LCAT and liver histology were analyzed.

RESULTS

Diabetic rats showed significantly (p < 0.05) increased plasma glucose (273.18 mg/dL), total cholesterol (142 mg/dL), triglycerides (126 mg/dL), free fatty acids (118 mg/dL), phospholipids (153 mg/dL), low-density lipoprotein (88.07 mg/dL), very low-density lipoprotein (25.2 mg/dL), atherogenic index, whereas a decrease in the levels of pancreatic insulin (97.48 ng/mg) and high-density lipoprotein (29.12 mg/dL). In addition, the activity of 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase (0.94 HMG-CoA ratio/(mevalonate) increased significantly in contrast to the activities of lipoprotein lipase (4.87 μmoles of glycerol liberated/h/L) and lecithin cholesterol acyltransferase (54.61 μmoles of cholesterol esterified/h/L) in diabetic rats. Treatment with myrtenal significantly (p < 0.05) improved the levels of plasma glucose, pancreatic insulin and lipid profiles. Moreover, the histopathological analysis of liver was also in agreement with the biochemical findings.

DISCUSSION AND CONCLUSIONS

The present study indicates that myrtenal possess antihyperglycaemic and antihyperlipidemic properties, and could potentially be a useful phytochemical in treating diabetes.

A newly developed silymarin nanoformulation as a potential antidiabetic agent in experimental diabetes

Aim: This study aimed to develop a new stable nanoformulation of silymarin (SM) with optimum enhanced oral bioavailability and to evaluate its effect as well as mechanism of action as a superior antidiabetic agent over native SM using streptozotocin-induced diabetic rats. Materials and methods: SM-loaded pluronic nanomicelles (SMnp) were prepared and fully characterized. Biochemical parameters were performed as well as histological, confocal and reverse-transcription polymerase chain reaction studies on pancreatic target tissues. Results & conclusion: SMnp were found to improve significantly the antihyperglycemic, antioxidant and antihyperlipidemic properties as compared with native SM. In addition, SMnp was found to be a more efficient agent over SM in the management of diabetes and its associated complications due to its superior bioavailability in vivo, and the controlled release profile of SM.

[Formula: see text]

Protective and hypoglycemic effects of celery seed on streptozotocin-induced diabetic rats: experimental and histopathological evaluation

AIMS

Diabetes mellitus is a major manifestation of metabolic disorder which presents with hyperglycemia (high levels of serum blood sugar). In the present study, we aimed to investigate the effects of celery seed extract on different biochemical factors and histopathological changes in normal and streptozotocin (STZ)-induced diabetic rats.

METHODS

A total of 35 male Wistar rats were divided into five groups (one normal and four diabetic groups). STZ was injected intraperitoneally to induce diabetes. The effects of hexane extract of celery seed and glibenclamide (as a positive control) were compared. Blood samples were analyzed on days 0, 18, and 33, and histopathological evaluations were performed at the end of the study.

RESULTS

Glucose, triglycerides, and cholesterol levels significantly decreased, whereas insulin and high-density lipoprotein (HDL) levels increased in the extract-administered groups, as compared to the negative diabetic control group (P < 0.0001). The concentrations of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum of the extract-administered groups were significantly less than the negative control group (P < 0.0001). Histopathological reports revealed significantly less atrophy, necrosis, and inflammation in the rats receiving celery seed extract compared to the negative control group.

CONCLUSIONS

The results indicated that celery seed extract can be effective in controlling hyperglycemia and hyperlipidemia in diabetic rats, and demonstrated its protective effects against pancreatic toxicity resulting from STZ-induction.

Bauhinia variegata (Caesalpiniaceae) leaf extract: An effective treatment option in type I and type II diabetes

Among various metabolic disorders, diabetes mellitus is one of the most common disorder. Present study was designed to evaluate the effectiveness of aqueous extract of Bauhinia variegata leaves (AE) in animal models of type I and type II diabetes. Type I diabetes was induced by streptozotocin at the dose of 55mg/kg (i.p.) in male Sprague Dawley rats while type II diabetes was induced by high fat diet and streptozotocin at the dose of 35mg/kg (i.p.). Diabetic animals were treated with AE at the dose of 250, 500 and 1000mg/kg. Glipizide (5mg/kg) was used as standard treatment drug. Treatment was given for 28days. Parameters evaluated were body weight, plasma glucose, cholesterol, triglyceride, aspartate aminotransferase, alanine transaminase, alkaline phosphatase, total proteins, albumin, creatinine and bun urea nitrogen. In type II diabetes, high density lipoprotein levels in plasma and plasma insulin level were also evaluated. Histopathological study of pancreases were carried out in type I study. AE showed significant decrease in plasma glucose significantly. AE was also found to decrease cholesterol, triglyceride, creatinine and blood urea nitrogen level in both types of diabetes. AE did not show any significant effect on plasma levels of aspartate aminotransferase, alanine transaminase, alkaline phosphatase. AE was found to increase the albumin and total protein levels. Histopathological study showed that AE decreases the necrotic changes in the pancreatic tissue. Aqueous extract of B. variegata leaves was found effective in treatment of both type I and type II diabetes.

Averrhoa bilimbi Linn.: A review of its ethnomedicinal uses, phytochemistry, and pharmacology

Averrhoa bilimbi Linn. is principally cultivated for medicinal purposes in many tropical and subtropical countries of the world. Literature survey about this plant shows that A. bilimbi is mainly used as a folk medicine in the treatment of diabetes mellitus, hypertension, and as an antimicrobial agent. The prime objective of this review is to accumulate and organize literature based on traditional claims and correlate those with current findings on the use of A. bilimbi in the management of different ailments. Through interpreting already published scientific manuscripts (1995 through 2015) retrieved from the different scientific search engines, namely Medline, PubMed, EMBASE, and Science Direct databases, published articles and reports covering traditional and scientific literature related to A. bilimbi's potential role against various ailments have been thoroughly evaluated, interpreted, and discussed. Several pharmacological studies have demonstrated the ability of this plant to act as antidiabetic, antihypertensive, thrombolytic, antimicrobial, antioxidant, hepatoprotective, and hypolipidemic agent. A. bilimbi holds great value in the complementary and alternative medicine as evidenced by the substantial amount of research on it. Therefore, we aimed to compile an up-to-date and comprehensive review of A. bilimbi that covers its traditional and folk medicine uses, phytochemistry, and pharmacology. Hence, this paper presents an up-to-date and comprehensive review of the ethnomedicinal uses, different chemical constituents, and pharmacological activities of A. bilimbi. So far, the biologically active agents have not been isolated from this plant and this can be a good scientific study for the future antidiabetic, antihypertensive, and antimicrobial implications. Hence, this review targets at emphasizing the diverse traditional claims and pharmacological activities of A. bilimbi with respect to carrying out more scientific studies to isolate active principles through advanced technology.

SIRT1 protects against myocardial ischemia-reperfusion injury via activating eNOS in diabetic rats

Background

Diabetic patients are more sensitive to myocardial ischemic injury than non-diabetic patients. Silent information regulator 1 (SIRT1) is a nicotinamide adenine dinucleotide-dependent histone deacetylase making the heart more resistant to ischemic injury. As SIRT1 expression is considered to be reduced in diabetic heart, we therefore hypothesized that up-regulation of SIRT1 in the diabetic heart may overcome its increased susceptibility to ischemic injury.

Methods

Male Sprague–Dawley rats were fed with high-fat diet and injected with streptozotocin once to induce diabetes. Diabetic rats received injections of adenoviral vectors encoding SIRT1 (Ad-SIRT1) at five myocardial sites. Four days after adenoviral injection, the rats were subjected to myocardial ischemia and reperfusion (MI/R). Outcome measures included left ventricular function, infarct size, cellular death and oxidative stress.

Results

Delivery of Ad-SIRT1 into the hearts of diabetic rats markedly increased SIRT1 expression. Up-regulation of SIRT1 in diabetic hearts improved cardiac function and reduced infarct size to the extent as in non-diabetic animals following MI/R, which was associated with reduced serum creatine kinase-MB, lactate dehydrogenase activities and cardiomyocyte apoptosis. Moreover, Ad-SIRT1 reduced the increase in the superoxide generation and malonaldialdehyde content and simultaneously increased the antioxidant capability. Furthermore, Ad-SIRT1 increased eNOS phosphorylation and reduced eNOS acetylation in diabetic hearts. NOS inhibitor L-NAME inhibited SIRT1-enhanced eNOS phosphorylation, and blunted SIRT1-mediated anti-apoptotic and anti-oxidative effects and cardioprotection.

Conclusions

Overexpression of SIRT1 reduces diabetes-exacerbated MI/R injury and oxidative stress via activating eNOS in diabetic rats. The findings suggest SIRT1 may be a promising novel therapeutic target for diabetic cardiac complications.

Antidiabetic mechanism of Coptis chinensis polysaccharide through its antioxidant property involving the JNK pathway

CONTEXT

Antidiabetic activity of Coptis chinensis Franch (Ranunculaceae) polysaccharide (CCPW) has been reported. However, its molecular mechanism remains unclear.

OBJECTIVE

An attempt was made to further verify the antidiabetic activity of CCPW on type 2 diabetes mellitus (T2DM) and elucidate the mechanism of antidiabetic activity.

MATERIALS AND METHODS

Male Wistar rats were fed with high-fat diet (HFD) and injected with streptozotocin (STZ) to generate a T2DM model. Effects of CCPW on fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), glutathione (GSH), glutathione peroxidases (GSH-Px), superoxide dismutases (SOD), catalase (CAT), malondialdehyde (MDA), c-jun n-terminal kinase (JNK), phosphorylated insulin receptor substrate 1 (phospho-IRS1), phosphorylated phosphatidylinositol 3 kinase (phospho-PI3Kp85) and glucose transporter 4 (Glut4) were investigated.

RESULTS

FBG level of diabetic rats could be significantly inhibited by 51.2, 42.7, and 23.3% through administration of CCPW at doses of 200, 100, and 50 mg/kg b.w., respectively (p < 0.01). CCPW also could significantly reduce TG by 19.2, 12.1, and 7.4%, and TC by 24.2, 20.9, and 18.7%, respectively (p < 0.05 or p < 0.01). CCPW showed an obvious antioxidant effect through increasing GSH-Px, SOD, and CAT activities, and decreasing GSH and MDA contents (p < 0.05 or p < 0.01). Furthermore, CCPW could inhibit JNK and phospho-IRS1 expression and promote the expression of phospho-PI3Kp85 and Glut4 compared with those in the DM group (p < 0.05 or p < 0.01).

DISCUSSION AND CONCLUSION

CCPW can produce antidiabetic activity in rats with T2DM through its antioxidative effect, which is closely related to the JNK/IRS1/PI3K pathway.

Effect of polycan, a β-glucan originating from Aureobasidium, on a high-fat diet-induced hyperlipemic hamster model

The aim of the present study was to analyze the effect of polycan, a β-glucan originating from Aureobasidium, on high-fat diet (HFD)-induced hyperlipemia and hepatic damage. A total of 30 hamsters were divided into 6 groups based on their body weight following acclimatization: control, sham, simvastatin (SIMVA) and 3 Polycan groups. In the polycan groups, Polycan, at three concentrations (31.25, 62.5 and 125 mg/kg), was administered orally once a day for 56 days, in addition to the HFD. On the day of sacrifice, changes in the body weight, food consumption, liver weight and serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride and total cholesterol (T-CHOL) were observed, as well as changes to the liver and aorta (thoracic and abdominal) histopathology and histomorphometry. The results from the polycan groups were compared with a SIMVA 10 mg/kg oral treatment group, in addition to the sham and vehicle control groups. After the HFD-induced hyperlipidemic hamsters were administered Polycan, there was no significant change in their body weight and food consumption when compared with the hamsters in the vehicle control group. However, the serum levels of AST, ALT, triglyceride, T-CHOL and LDL were significantly reduced in a dose-dependent manner when compared with the vehicle control group (P<0.05). Furthermore, the levels of liver steatosis and arteriosclerosis in the abdominal and thoracic aorta were significantly decreased in a dose-dependent manner (P<0.01). In the SIMVA-treated group, body weight (P<0.05), the serum level of lipids (triglyceride, T-CHOL and LDL; P<0.01) and the level of arteriosclerosis (P<0.01) were significantly reduced when compared with the vehicle control group. However, liver weight and the serum levels of AST, ALT, and liver steatosis increased when compared with the vehicle control group. Based on these results, it was concluded that polycan exerts a favorable effect in decreasing HFD-induced hyperlipemia and associated atherosclerosis, with relatively good protective effects on liver damage.

Thermal degradation kinetics of nicotinic acid, pantothenic acid and catechin derived from Averrhoa bilimbi fruits

The nicotinic acid, pantothenic acid and catechin obtained from Averrhoa bilimbi suffer from thermal degradation.

Constituents of Indonesian Medicinal Plant Averrhoa bilimbi and Their Cytochrome P450 3A4 and 2D6 Inhibitory Activities

As constituents of Averrhoa bilimbi leaves we identified three new compounds (1-3) together with 12 known ones (4-15); their inhibitory activities on cytochrome P450 3A4 (CYP3A4) and 2D6 (CYP2D6) were examined. Among the isolated compounds, the mixture of 1 and 2, and compounds 4 and 9 showed strong inhibition on CYP3A4, but mild or no inhibition on CYP2D6. These compounds revealed the characteristics of 1) time- and concentration-dependent inhibition, 2) requirement of NADPH for the inhibition, 3) no protection by nucleophiles, and 4) suppression of the inhibition by competitive inhibitor. Thus, they are suggested to be mechanism-based inactivators of CYP3A4 and CYP2D6. The kinetic parameters for the inactivation (kinact and KI) were 0.19 min–1 and 36.7 μM for the mixture of 1 and 2, 0.126 min–1 and 10.5 μM for 4, and 0.29 min–1 and 23.4 μM for 9.

Ethanol extract of Butea monosperma bark modulates dyslipidemia in streptozotocin-induced diabetic rats

CONTEXT

Dyslipidemia is one of the major risk factors for cardiovascular disease in diabetes mellitus (DM). The availability of multiple lipid-lowering drugs and supplements provides new opportunities for patients to regulate lipid levels.

OBJECTIVE

The present study was designed to evaluate the effect of Butea monosperma Lam. (Fabaceae) bark extract in diabetes-induced dyslipidemia.

MATERIALS AND METHODS

A daily dose of B. monosperma bark extract (BMBE, 500 mg/kg body weight) was given orally to streptozotocin (STZ)-induced diabetic rats for 60 d. Several indices such as blood glucose, insulin, glycosylated hemoglobin, TC, TG, high-density lipoprotein-cholesterol (HDL-C), apo A1, apo B, activities of lipogenic enzymes in tissues, liver function tests, and histopathology of liver were analyzed to assess the modulation of STZ-induced diabetic dyslipidemia by B. monosperma bark.

RESULTS

BMBE significantly reduced blood glucose (40.79%) and increased plasma insulin (37.5%) levels in diabetic rats. Altered levels of serum lipids, lipoproteins, and activities of lipogenic enzymes in tissues were partially restored upon the administration of BMBE in diabetic rats. Liver function tests and histopathological examination revealed that consumption of BMBE at a dose of 500 mg/kg body weight had no toxic effects in experimental rats.

CONCLUSION

The findings suggest that BMBE supplementation could ameliorate dyslipidemia in DM.

Acute oxalate nephropathy due to 'Averrhoa bilimbi' fruit juice ingestion

Irumban puli (Averrhoa bilimbi) is commonly used as a traditional remedy in the state of Kerala. Freshly made concentrated juice has a very high oxalic acid content and consumption carries a high risk of developing acute renal failure (ARF) by deposition of calcium oxalate crystals in renal tubules. Acute oxalate nephropathy (AON) due to secondary oxalosis after consumption of Irumban puli juice is uncommon. AON due to A. bilimbi has not been reported before. We present a series of ten patients from five hospitals in the State of Kerala who developed ARF after intake of I. puli fruit juice. Seven patients needed hemodialysis whereas the other three improved with conservative management.

Antihyperglycemic and antihyperlipidemic activities of 2-(4-[(2-hydroxybenzyl) amino]-phenyl amino-methyl)-phenol in STZ induced diabetic rats

Oral administration of 2-(4-[(2-hydroxybenzyl) amino]-phenyl amino-methyl)-phenol (HBPMP) (30 mg/kg) to Streptozotocin (STZ) rats produced significant antidiabetic activity after 6 h of HBPMP administration. Treatment of the STZ rats with HBPMP (30 mg/kg/day) for 30 days resulted in a significant decrease in their Fasting Blood Glucose (FBG), Serum Total Cholesterol (TC), Low Density Lipoprotein-Cholesterol (LDL-C), Very Low Density Lipoprotein-Cholesterol (VLDL-C) and triglycerides (TG) along with an increase in serum High Density Lipoprotein-Cholesterol (HDL-C) levels. Activities of Serum Aspartate transaminase (AST), Alanine transaminase (ALT) and Alkaline phosphatase (ALP) and levels of blood urea and creatinine were improved to near normal levels in the treated STZ rats indicating the protective role of the HBPMP against liver and kidney damage and its non-toxic property. In conclusion, HBPMP possesses antihyperglycemic and antihyperlipidemic activities.

Green Synthesis of Gold and Silver Nanoparticles UsingAverrhoa bilimbiFruit Extract

We report on rapid one-step green synthesis of gold and silver nanoparticles using fruit extract ofAverrhoa bilimbi Linn. UV-Vis absorption spectroscopy was used to monitor the quantitative formation of gold and silver nanoparticles. The characteristics of the obtained gold and silver nanoparticles were studied using UV-Vis absorption spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Energy-dispersive spectroscopy (EDX). UV/Vis spectrum showed Surface Plasmon Resonance (SPR) for both gold and silver nanoparticles at 540 and 420 nm. The EDX spectrum of the solution containing gold and silver nanoparticles confirmed the presence of elemental gold and silver signals. The average diameter of the prepared nanoparticles in solution was about 50–150 nm. Synthesized particles were either hexagonal or rhomboidal in shape. This synthesis approach of gold and silver nanoparticles is cost effective and can be widely used in biological systems. The effect of fruit extract and metal ion concentration was also studied.

α-Glucosidase inhibitory activity of selected Philippine plants

ETHNOPHARMACOLOGICAL RELEVANCE

Antidesma bunius Spreng. (Phyllantaceae), Averrhoa bilimbi L. (Oxalidaceae), Biophytum sensitivum (L.) DC. (Oxalidaceae), Ceriops tagal (Perr.) C.B. Rob. (Rhizophoraceae), Kyllinga monocephala Rottb. (Cyperaceae), and Rhizophora mucronata Lam. (Rhizophoraceae) are used as remedies to control diabetes. In the present study, these plants were screened for their potential α-glucosidase inhibitory activity.

MATERIALS AND METHODS

The 80% aqueous ethanolic extracts were screened for their α-glucosidase enzyme inhibitory activity using yeast alpha glucosidase enzyme.

RESULTS

Except for A. bilimbi with IC(50) at 519.86±3.07, all manifested a significant enzyme inhibitory activity. R. mucronata manifested the highest activity with IC(50) at 0.08±1.82 μg mL(-1), followed by C. tagal with IC(50) at 0.85±1.46 μg mL(-1) and B. sensitivum with IC(50) at 2.24±1.58 μg mL(-1).

CONCLUSION

This is the first report on the α-glucosidase inhibitory effect of the six Philippine plants; thus, partly defining the mechanism on why these medicinal plants possess antidiabetic properties.

Antihyperglycemic and antihyperlipidemic activities of ethanolic extract of Zygophyllum album in streptozotocin-induced diabetic mice

Zygophyllum album has been mentioned in Tunisian system of folk medicine to be of value in the treatment of diabetes mellitus. The present study was designed to investigate the possible antihyperglycemic effects of ethanolic extracts of the whole plant of Z. album on blood glucose, plasma insulin, serum lipids and hepatic glycogen and metabolism enzymes of carbohydrate in streptozotocin (STZ)-induced diabetic mice. Administration of the ethanolic extract from plant (100 and 300 mg/kg body weight) for 14 days resulted in significant reduction in plasma glucose, cholesterol, triglycerides, low-density lipoprotein, very-low-density liprotein, hepatic glucokinase and glycogen in STZ diabetic mice. In addition to that, significant increase in plasma high-density lipoprotein, hepatic phosphofructokinase and glucose-6 phosphate dehydrogenase was observed in STZ diabetic mice. After administration of the ethanolic extract, the increased level of plasma insulin is not significant in diabetic mice. In conclusion, the present results showed that the ethanolic extract of Z. album possesses significant antihyperglycemic and antihyperlipidemic effects in experimental model of diabetes mellitus.

Ajuga iva aqueous extract improves reverse cholesterol transport in streptozotocin-induced diabetic rat

Objectives

The aim of this study was to determine the effects of Ajuga iva aqueous extract on lecithin : cholesterol acyltransferase (LCAT) activity and amount and composition of high-density lipoprotein (HDL)2 and (HDL)3, in streptozotocin (STZ)-induced diabetic rats.

Methods

Diabetes was induced in male Wistar rats by intraperitoneal injection of STZ (60 mg/kg body weight). Diabetic rats (n = 12) were divided into two groups. The diabetic control group (D) received a 20% casein diet and the diabetic treated group received the same diet supplemented with A. iva aqueous extract (0.5 g/100 g diet) (DAi), for 4 weeks.

Key findings

Total cholesterol and HDL3-C were respectively decreased by 32% and 55% in the DAi group compared with the D group, whereas HDL2-C was increased by 30%. The amounts of HDL2 and HDL3, which were the sum of apolipoproteins, unesterified cholesterol (UC), cholesteryl esters (CEs), triacylglycerols (TGs) and phospholipids (PLs), showed no significant difference. A. iva treatment increased LCAT by 33% and its cofactor-activator, apolipoprotein A-I, by 58%. HDL3-PL (enzyme substrate) and HDL3-UC (acyl group acceptor) were respectively decreased by 70% and 57%, whereas HDL2-CE (product of LCAT reaction) was enhanced by 30%.

Conclusions

In STZ-induced diabetic rats, A. iva improves reverse cholesterol transport by enhancing LCAT activity, leading to anti-atherogenic effects.

Obesity: the preventive role of the pomegranate (Punica granatum)

Obesity represents a rapidly growing threat to the health of populations in an increasing number of countries. Diet intervention has been proposed as one of the strategies for weight loss and weight maintenance. Traditionally, the pomegranate, including its roots, tree bark, fruit juice, leaves, and flowers, has been used to treat some conditions such as diarrhea, hemorrhage, acidosis, and microbial infections. Pomegranate extracts have been found to have strong anti-inflammatory, antioxidant, and even antitumor properties in vivo and in vitro. More recently, positive effects on fat reduction have been shown using the pomegranate and its extracts. Many of the beneficial effects are related to the presence of anthocyanins, tannins, and very high levels of antioxidants, including polyphenols and flavonoids. Many studies have explored the effects of the pomegranate in obesity, and various mechanisms have been proposed as to how these different extracts help in fat reduction. This article provides an overview of the work done addressing the potential benefits of the pomegranate on obesity and assesses the efficacy of intervention by means of the pomegranate and its extracts. Human studies in this field are still limited and need more attention that would help in understanding the preventive and protective roles pomegranate extracts have on obesity.

A pharmacological appraisal of medicinal plants with antidiabetic potential

Diabetes mellitus is a complicated metabolic disorder that has gravely troubled the human health and quality of life. Conventional agents are being used to control diabetes along with lifestyle management. However, they are not entirely effective and no one has ever been reported to have fully recovered from diabetes. Numerous medicinal plants have been used for the management of diabetes mellitus in various traditional systems of medicine worldwide as they are a great source of biological constituents and many of them are known to be effective against diabetes. Medicinal plants with antihyperglycemic activities are being more desired, owing to lesser side-effects and low cost. This review focuses on the various plants that have been reported to be effective in diabetes. A record of various medicinal plants with their established antidiabetic and other health benefits has been reported. These include Allium sativa, Eugenia jambolana, Panax ginseng, Gymnema sylvestre, Momrodica charantia, Ocimum sanctum, Phyllanthus amarus, Pterocarpus marsupium, Trigonella foenum graecum and Tinospora cordifolia. All of them have shown a certain degree of antidiabetic activity by different mechanisms of action.

Effect of atorvastatin and hydroxychloroquine combination on blood glucose in alloxan-induced diabetic rats

Objective:

To evaluate the antihyperglycemic activity of atorvastatin and hydroxychloroquine combination in alloxan-induced diabetic rats.

Materials and Methods:

Alloxan induced diabetic Wistar male rats were randomized into six groups of 6 rats each. (Normal rats, diabetic control, atorvastatin (ATV), hydroxychloroquine (HCQ), ATV 5 mg /kg + HCQ 100 mg/kg, and ATV 10 mg/kg + HCQ 200 mg/kg). The rats were treated for 9 days and blood samples were collected at baseline and end of therapy. These samples were analyzed for plasma glucose by autoanalyzer. Changes in body weight, water, food intakes and total protein content were also recorded.

Results:

Atorvastatin and hydroxychloroquine alone and in combination reported significant fall in blood glucose level from baseline. Fall in glucose level was significantly more in high dose combination of atorvastatin and hydroxychloroquine (ATV: 10 mg/kg + HCQ: 200 mg/kg) as compared to other study treatment groups (ATV: 17% Vs HCQ: 7% Vs ATV 5mg/kg + HCQ 100mg /kg: 14% Vs ATV 10mg/kg + HCQ 200mg /kg: 21%; p<0.01). ATV and HCQ individually and in combination also improved the body weight loss. The weight gain was significantly more in combination treated rats as compared to positive control group and greater than those who received atorvastatin and hydroxychloroquine alone. Rats treated with the combination also reported significant decrease in food intake and significant increase in total protein.

Conclusion:

Increased hypoglycemic effect in combination may be due to potentiation or synergism between HCQ and ATV. Further studies are required to demonstrate clinically significant antidiabetic effect.

Synergistic antihyperglycemic effects between plant-derived oleanolic acid and insulin in streptozotocin-induced diabetic rats

Studies from our laboratories indicate that Syzygium cordatum leaf extract contains triterpene mixtures [oleanolic acid (OA) and ursolic acid (UA)] with hypoglycemic properties. The aims of this study were to investigate the hypoglycemic effects of Syzygium aromaticum-derived OA and whether OA influenced the blood glucose lowering effects of insulin in streptozotocin (STZ)-induced diabetic rats. We envisaged that OA may provide a strategy with different mechanism of action for effective diabetic therapy because no single-marketed antidiabetic drug is capable of achieving long-lasting blood glucose control. The effects of various doses of OA and/or standard antidiabetic drugs on blood glucose were monitored in nondiabetic and STZ-induced diabetic rats given a glucose load after an 18-h fast. Rats treated with deionized water and standard antidiabetic drugs acted as untreated and treated positive controls, respectively. Blood glucose concentrations were measured at 15-min intervals for the first hour and hourly thereafter for 3 h. Blood glucose concentrations were also monitored in animals treated with OA and/or standard antidiabetic drugs for 5 weeks. OA like insulin decreased blood glucose concentrations in nondiabetic and STZ-induced diabetic rats. Combined OA and insulin treatment had even greater antihyperglycemic response, suggestive of a synergistic effect of the two. After 5 weeks, STZ-induced diabetic rats exhibited hyperglycemia and depleted hepatic and muscle glycogen concentrations. OA treatment lowered the blood glucose with concomitant restoration of glycogen concentrations to near normalcy. Our results suggest that OA may have a role in improving insulin sensitivity. These findings merit further research in this field.