Chitosan and sodium alginate nanocarrier system: Controlling the release of rapeseed-derived peptides and improving their therapeutic efficiency of anti-diabetes

Rapeseed-derived peptides (RPPs) can maintain the homeostasis of human blood glucose by inhibiting Dipeptidyl Peptidase-IV (DPP-IV) and activating the calcium-sensing receptor (CaSR). However, these peptides are susceptible to hydrolysis in the gastrointestinal tract. To enhance the therapeutic potential of these peptides, we developed a chitosan/sodium alginate-based nanocarrier to encapsulate two RPP variants, rapeseed-derived cruciferin peptide (RCPP) and rapeseed-derived napin peptide (RNPP). A convenient three-channel device was employed to prepare chitosan (CS)/sodium alginate (ALG)-RPPs nanoparticles (CS/ALG-RPPs) at a ratio of 1:3:1 for CS, ALG, and RPPs. CS/ALG-RPPs possessed optimal encapsulation efficiencies of 90.7 % (CS/ALG-RNPP) and 91.4 % (CS/ALG-RCPP), with loading capacities of 15.38 % (CS/ALG-RNPP) and 16.63 % (CS/ALG-RCPP) at the specified ratios. The electrostatic association between CS and ALG was corroborated by zeta potential and near infrared analysis. 13C NMR analysis verified successful RPPs loading, with CS/ALG-RNPP displaying superior stability. Pharmacokinetics showed that both nanoparticles were sustained release and transported irregularly (0.43 < n < 0.85). Compared with the control group, CS/ALG-RPPs exhibited significantly increased glucose tolerance, serum GLP-1 (Glucagon-like peptide 1) content, and CaSR expression which play pivotal roles in glucose homeostasis (*p < 0.05). These findings proposed that CS/ALG-RPPs hold promise in achieving sustained release within the intestinal epithelium, thereby augmenting the therapeutic efficacy of targeted peptides.

Allelochemicals from the seaweeds and their bioprospecting potential

Allelochemicals are secondary metabolites which function as a natural protection against grazing activities by algae and higher plants. They are one of the major metabolites engaged in the interactions of organisms. The chemically mediated interactions between organisms significantly influence the functioning of the ecosystems. Most of these compounds are secondary metabolites comprising sterols, terpenes, and polyphenols. These compounds not only play a defensive role, but also exhibit biological activities such as antioxidants, anti-cancer, anti-diabetes, anti-inflammation, and anti-microbial properties. This review article discusses the current understanding of the allelochemicals of seaweeds and their bioprospecting potential that can bring benefit to humanity. Specifically, the bioactive substances having specific health benefits associated with the consumption or application of seaweed-derived compounds. The properties of such allelochemicals can have implications for bioprospecting pharmaceutical, nutraceutical and cosmetic applications.

1,5-Anhydro-d-glucitol derivative and galloylated flavonoids isolated from the leaves of Acer ginnala Maxim. as dual inhibitors of PTP1B and α-glucosidase enzymes: In vitro and in silico studies

Four undescribed compounds (two 1,5-anhydro-d-glucitol derivatives and two galloyl derivatives) and fourteen known compounds were isolated and structurally identified from leaves of Acer ginnala Maxim. (Amur maple). Structures and absolute configurations of the four undescribed compounds were determined using extensive analysis of NMR spectroscopic, HRESI-MS, modified Mosher ester method, and comparison with spectroscopic data of known compounds. Bioactivity evaluation revealed that the isolated 1,5-anhydro-d-glucitol derivative, galloylated flavonol rhamnosides, and galloylated flavanols had inhibitory effects on both protein tyrosine phosphatase-1B (PTP1B, IC₅₀ values ranging of 3.46-12.65 μM) and α-glucosidase (IC₅₀ values ranging of 0.88-6.06 μM) in comparison with a positive control for PTP1B (ursolic acid, IC₅₀ = 5.10 μM) or α-glucosidase (acarbose, IC₅₀ = 141.62 μM). A combination of enzyme kinetic analysis and molecular docking provided additional evidence in favor of their inhibitory activities and mechanism. These data demonstrate that A. ginnala Maxim. together with its constituents are promising sources of potent candidates for developing novel anti-diabetic medications.

Biological characterization of microwave based synthesized ZnO and Ce doped ZnO nanoflowers impeded chitosan matrix with enhanced antioxidant and anti-diabetic properties

The chitosan matrix was used as a substrate for ZnO nanoflowers (ZnO/CH) and Ce-doped ZnO nanoflowers (Ce-ZnO/CH) by microwave-induced hydrothermal synthesis processes. The obtained hybrid structures were assessed as enhanced antioxidant and antidiabetic agents considering the synergetic effect of the different components. The integration of chitosan and cerium induced significantly the biological activity of ZnO flower-like particles. Ce-doped ZnO nano-flowers show higher activities than both ZnO nanoflowers and ZnO/CH composite reflecting the strong effect of surface electrons that were formed by the doping process as compared to the high interactive interface of the chitosan substrate. As an antioxidant the synthetic Ce-ZnO/CH composite achieved remarkable scavenging efficiencies for DPPH (92.4 ± 1.33 %), nitric oxide (95.2 ± 1.81 %), ABTS (90.4 ± 1.64 %), and superoxide (52.8 ± 1.22 %) radicals which are significantly higher values than Ascorbic acid as standard and the commercially used ZnO nanoparticles. Also, its antidiabetic efficiency enhanced greatly achieving strong inhibition effects on porcine α-amylase (93.6 ± 1.66 %), crude α-amylase (88.7 ± 1.82 %), pancreatic α-glucosidase (98.7 ± 1.26 %), crude intestinal α-glucosidase (96.8 ± 1.16 %), and amyloglucosidase (97.2 ± 1.72 %) enzymes. The recognized inhibition percentages are notably higher than the determined percentages using miglitol drug and slightly higher than acarbose. This recommends the Ce-ZnO/CH composite as a potential antidiabetic and antioxidant agent compared with the high cost and the reported side effects of the commonly used chemical drug.

A clinical trial on anti-diabetic efficacy of submerged culture medium of Ceriporia lacerata mycelium

BACKGROUND

Increased glucose level and insulin resistance are major factors in Type 2 diabetes mellitus (T2M), which is chronic and debilitating disease worldwide. Submerged culture medium of Ceriporia lacerata mycelium (CLM) is known to have glucose lowering effects and improving insulin resistance in a mouse model in our previous studies. The main purpose of this clinical trial was to evaluate the functional efficacy and safety of CLM in enrolled participants with impaired fasting blood sugar or mild T2D for 12 weeks.

METHODS

A total of 72 participants with impaired fasting blood sugar or mild T2D were participated in a randomized, double-blind, placebo-controlled clinical trial. All participants were randomly assigned into the CLM group or placebo group. Fasting blood glucose (FBG), HbA1c, insulin, C-peptide, HOMA-IR, and HOMA-IR by C-peptide were used to assess the anti-diabetic efficacy of CLM for 12 weeks.

RESULTS

In this study, the effectiveness of CLM on lowering the anti-diabetic indicators (C-peptide levels, insulin, and FBG) was confirmed. CLM significantly elicited anti-diabetic effects after 12 weeks of ingestion without showing any side effects in both groups of participants. After the CLM treatment, FBG levels were effectively dropped by 63.9% (ITT), while HOMA-IR level in the CLM group with FBG > 110 mg/dL showed a marked decrease by 34% up to 12 weeks. Remarkably, the effect of improving insulin resistance was significantly increased in the subgroup of participants with insulin resistance, exhibiting effective reduction at 6 weeks (42.5%) and 12 weeks (61%), without observing a recurrence or hypoglycemia. HbA1c levels were also decreased by 50% in the participants with reduced indicators (FBG, insulin, C-peptide, HOMA-IR, and HOMA-IR). Additionally, it is noteworthy that the levels of insulin and C-peptide were significantly reduced despite the CLM group with FBG > 110 mg/dL. No significant differences were detected in the other parameters (lipids, blood tests, and blood pressure) after 12 weeks.

CONCLUSION

The submerged culture medium of CLM showed clinical efficacy in the improvement of FBG, insulin, C-peptide, HbAc1, and HOMA-index. The microbiome-based medium could benefit patients with T2D, FBG disorders, or pre-diabetes, which could guide a new therapeutic pathway in surging the global diabetes epidemic.

Antioxidant activity and antidiabetic activities of Northern Thai indigenous edible plant extracts and their phytochemical constituents

Diabetes mellitus is the most common non-infective disease characterized by hyperglycemia (high level of blood glucose). Formation of advanced glycation end products (AGEs) in long termed-hyperglycemia and oxidative stress are the key factors to accelerate diabetic complications. To screen potential candidates for treating diabetes, total phenolic content, total flavonoid content, antioxidant activity from crude extracts of some Thai edible plants were primarily assessed, and the inhibiting potential of diabetes and its complications provided from some of these plants were evaluated in terms of their inhibitory activities of α-amylase, α-glycosidase, and AGEs formation. The highest amounts of phenolic and flavonoid compounds were found in the ethanolic extract of Caesalpinia mimosoides (S20, 12.63 ± 1.70 mg GAE/g DW) and Glochidion hirsutum (S8, 3.02 ± 0.25 mg CE/g DW), respectively. The highest antioxidant activity was found in Schinus terebinthifolius Raddi (S26, 217.94 ± 32.30 μg AAE/g DW) whereas the highest inhibitory activities of α-amylase and α-glycosidase were obtained from Basella alba L. (S11, IC₅₀ = 0.21 ± 0.01 mg/ml) and S. terebinthifolius (S26, IC₅₀ = 0.05 ± 0.02 mg/ml) respectively. The inhibitory effects of AGEs formation were studied in vitro using two model systems: BSA-glucose and BSA-methylglycoxal (MGO). The extracts of Glochidion hirsutum (Roxb.) Voigt (S8, IC₅₀ = 0.20 ± 0.01 mg/ml) and Polygonum odoratum Lour. (S13, IC₅₀ = 0.03 ± 0.01 mg/ml) exhibited the inhibitory activity of AGEs formation derived from glucose (BSA-glucose system) stronger than aminoguanidine (AG) (0.26 ± 0.00 mg/ml), which is a common AGEs formation inhibitory drug. By BSA-MGO assay, the inhibition of some selected extracts in this study (G. hirsutum, G. sphaerogynum, and S. terebinthifolius with IC₅₀ = 0.11 ± 0.01, 0.11 ± 0.01, and 0.10 ± 0.00 mg/ml, respectively) were slightly less efficient than AG (the IC₅₀ = 0.06 ± 0.00 mg/ml). These results indicated that some selected Thai edible plants in this present study provided potential applications towards the prevention of diabetes and their complications via the inhibitory of α-amylase, α-glycosidase, AGEs formation, and oxidative stress. This fundamental information would be important for alternative drug discovery and nutritional recommendations for diabetic patients.

Synthesis of vildagliptin loaded acrylamide-g-psyllium/alginate-based core-shell nanoparticles for diabetes treatment

Diabetes mellitus has become a major public health concern all over the world. Vildagliptin is one of the antidiabeticdrug that can overcome the existing problem of this prevalent disease. Present study aims to synthesize and investigate the role of vildagliptin-loaded core-shell nanoparticle of grafted psyllium and alginate (VG@P/A-NPs) in anti-diabetes application. FTIR, SEM, XRD, ¹³CNMR and zeta analyzer were used for characterization of the core-shell nanoparticles (VG@P/A-NPs). The synthesized acrylamide-grafted-psyllium was also optimized through varying grafting parameters such as acrylamide and ceric ammonium nitrate (CAN) concentration, time and temperature to obtain the maximum yield of acrylamide-grafted-psyllium. Rheological analysis of pure psyllium, grafted psyllium and alginate were also performed. For biological studies, the first cytotoxicity of grafted psyllium and VG@P/A-NPs were examined on human lung adenocarcinoma cell line A549 in which it was observed that VG@P/A-NPs did not exhibited any toxicity. The antidiabetic potential of VG@P/A-NPs was investigated by glucose uptake assay, using TNF-α induced insulin resistance skeletal cell model using mouse muscle L6 cell line. The insulin signaling impaired cell line displayed a highly significant (p < 0.0001) dose-dependent increase in glucose uptake after treatment with increasing doses of VG@P/A-NPs.The drug release behavior of VG@P/A-NPs was examined at various pH and the highest drug release (98 %) was obtained at pH (7.4). The drug release kinetic data was following the Higuchi (R² = 0.9848) kinetic model, suggesting the release of drug from vildagliptin-loaded grafted psyllium-alginate core-shell nanoparticles (VG@P/A-NPs) as a square root of time-dependent process and diffusion controlled. This study provides an economical and environment-friendly approach towards the synthesis of VG@P/A-NPs with antidiabetes applications.

Comparative Analysis of In Vitro Enzyme Inhibitory Activities and Phytochemicals from Platycladus orientalis (L.) Franco via Solvent Partitioning Method

The extraction of plant bioactive compounds from Platycladus orientalis (L.) Franco remains a great challenge due to the different chemical groups. This study aimed to compare the bioactive compounds with enzyme inhibitory effect from P. orientalis via solvent partitioning method. Dried leaf samples were macerated and fractionated with six solvents of different polarities. The phenolic, flavonoid, tannin, saponin, alkaloid and pharmacological activities including anti-inflammatory, anti-diabetic, antioxidant and anti-glycation potential were compared across the six plant fractions. Toxicity assessment was performed with an in vivo brine shrimp model. The varying levels of bioactive compounds in ethyl acetate (phenolics, flavonoids), hexane (saponins, tannins) and chloroform (alkaloids) fractions clearly demonstrated the significant impact of solvent polarity on the extraction of bioactive compounds. The reducing potential (r = 0.67), IC₅₀ of α-amylase inhibition (r = -0.71), IC₅₀ of advanced glycation end-product inhibition (r = -0.93) and dicarbonyl compound inhibition (r = 0.57) in the plant fractions were correlated (p<0.05) with the flavonoids. Besides, the alkaloid, saponin and tannin were associated with cyclooxygenase-1 inhibitory activity. Principal component analysis confirmed that solvent polarity (23.9%) and plant extraction yield (37.1%) collectively contributed to 61% of bioactivity variation in P. orientalis. Among the six plant fractions, ethyl acetate fraction exhibited relatively high anti-inflammatory, anti-diabetic, antioxidant and anti-glycation potential while the non-toxic methanolic and aqueous fractions displayed optimal hyaluronidase and lipoxygenase inhibitory activities, respectively. The current study has identified semi-polar ethyl acetate fraction of P. orientalis as a good alternative source of bioactive compounds for future pharmaceutical product development.

Anti-oxidative and anti-hyperglycemic properties of Agastache foeniculum essential oil and oily fraction in hyperglycemia-stimulated and lipopolysaccharide-stimulated macrophage cells: In vitro and in silico studies

ETHNOPHARMACOLOGICAL RELEVANCE

Hyperglycemia (HG) and lipopolysaccharide (LPS) often promote superoxide accumulation, which may increase oxidative stress. Reducing superoxide production in hyperglycemia and the inflammatory condition is an emerging way to reduce protein and lipid oxidation and diabetes complication.

AIM OF STUDY

To examine the effect of Agastache foeniculum essential oil (AFEO) and oil fraction (AFoil) on HG- and LPS-stimulated oxidative stress, the pathogenicity of AFEO and AFoil on oxidative stress was assessed.

METHODS

The stimulatory effects of AFEO and AFoil on the activity and expression of NADH oxide (NOX), catalase (CAT), superoxide dismutase (SOD), and the expression of nuclear respiratory factor 2 (NRF2) and nuclear factor-kappa B (NF-kB) in the stimulated macrophage cell line, J774.A1, was studied. The interaction patterns of AFEO and AFoil components with NOX, SOD, CAT, NRF2, and NF-kB proteins were also deduced using molecular docking.

RESULTS

Estragole was the main ingredient in AFEO (97%). Linolenic acid (32.10%), estragole (16.22%), palmitic acid (12.62%), linoleic acid (12.04%), and oleic acid (8.73%) were the major chemical components of the AFoil. NOX activation was stimulated in macrophage cells by HG and LPS. At 20 μg/mL, AFEO and AFoil decreased NOX activity while increased SOD and CAT activities in stimulated macrophages. AFoil with estragole and omega-3 fatty acids was better than AFEO with estragole in anti-hyperglycemic and anti-oxidative activity. According to molecular docking research, estragole, linoleic acid, and linolenic acid bind to different hydrophobic pockets of NOX, SOD, CAT, NFR2, and NF-kB using hydrogen bonds, van der Waals bonds, pi-alkyl, and pi-anion interactions, with different binding energies.

CONCLUSION

AFEO and AFoil showed antioxidant and anti-diabetic activity. The mechanisms in lowering oxidative stress markers depended on down-regulating superoxide-producing enzymes and up-regulating superoxide-removing enzymes at gene and protein levels. The AFoil emulsion can be used to reduce the detrimental impacts of hyperglycemia and oxidative stress.

Multiple in vitro biological effects of phenolic compounds from Terminalia chebula var. tomentella

ETHNOPHARMACOLOGICAL RELEVANCE

Terminalia chebula (TC), a well-known Indian Ayurvedic medicine introduced into China in the Sui and Tang Dynasties, has been recorded and used medicinally as Fructus Chebulae, together with its variety tomentella (TCT) in the Chinese Pharmacopoeia. They have been also used commonly for the treatment of diabetes mellitus by Tibetan medicine.

AIM OF THE STUDY

To investigate the main bioactive and therapeutic principles in the fruits of TCT, based on the extensive evaluation of their anti-inflammatory and hypoglycemic activities.

MATERIALS AND METHODS

The TCT fresh fruits were analyzed by HPLC and separated further by column chromatography and preparative HPLC. The isolated compounds were identified by extensive spectroscopic analyses, including 1D/2D NMR, MS, UV, IR and ECD. Anti-inflammatory activity was evaluated by inhibition of NO production in RAW264.7 cells. The specific iNOS (PDB ID: 3E7G) structure was prepared by Discovery Studio 4.0, and the molecular docking simulation was performed on GOLD (version 5.2.2). Hypoglycemic activity was measured using the substrate solution of 4-nitrophenyl-α-d-glucopyranoside enzyme and buffer solution.

RESULTS

The HPLC analysis method of polyphenols in the fruits of TCT was established, and 13 main chromatographic peaks were identified, including six hydrolyzable tannins (2, 4-7, 10-11), three simple phenols (12-14), and one oleanane pentacyclic triterpene, arjungenin. Extensive chromatographic separation of TCT fresh fruits yielded 14 compounds, including one new natural hydrolyzable tannin, 2,3-(S)-HHDP-6-O-galloyl-d-glucose (1). The known compounds were identified as 10 hydrolyzable tannins (2-11) and three simple phenols (12-14). Compounds 10 (IC₅₀ = 36.43 ± 0.21 μM), 11 (IC₅₀ = 42.28 ± 0.09 μM) displayed stronger NO inhibitory activity than the positive control L-NMMA (IC₅₀ = 42.34 ± 0.66 μM), while 2, 4, and 9 showed moderate inhibitory activity against NO production. Further molecular docking simulation of specific iNOS on 10 and 11, as well as five previously isolated lignans 15-19 showed that there were no obvious rules between docking results and the in vitro NO inhibitory activity for hydrolyzable tannins (10 and 11), while the mechanism of anti-inflammatory activity for lignans was related to the substitution of conjugated aldehyde groups. Moreover, most of the hydrolyzable tannins (1-2, 4-5, 9-11) and simple phenol (12) displayed stronger inhibitory effects on α-glucosidase than the positive control, quercetin (IC₅₀ = 6.118 ± 0.071 μM), with IC₅₀ values ranging from 0.079 to 16.494 μM. Among these bioactive isolates, the hydrolyzable tannins 2, 4-5, and 9-11, and simple phenol 12 are major chemical components in TCT fruit.

CONCLUSIONS

The results showed that lignans and hydrolyzed tannins are the main active ingredients of TCT fruits, responsible for the traditional treatment of sore throat and cough. Moreover, hydrolyzed tannins and simple phenolic compounds with potential hypoglycemic activity are closely related to the ethno-pharmacological uses of TCT fruits on diabetes in Tibetan medicine.

Syringaldehyde promoting intestinal motility with suppressing α-amylase hinders starch digestion in diabetic mice

The antihyperglycemic potential of syringaldehyde has been previously investigated; however, the underlying mechanism remains unclear. In this study, we performed a postprandial glucose test (in vivo) including oral glucose tolerance test (OGTT) and oral starch tolerance test (OSTT) in fructose-induced diabetic mice on a high-fat diet for mimicking type 2 diabetes to explore the hypoglycemic efficacy of syringaldehyde and the underlined molecular involvement of syringaldehyde in a glucose-lowering effect. The results revealed that syringaldehyde dose-dependently suppressed blood glucose in both the OSTT and OGTT when referenced to acarbose and metformin, respectively. Surprisingly, syringaldehyde triggered jejunum motility (ex vivo) via activation of the muscarinic-type acetylcholine receptor. By performing virtual screening with molecular docking, the data showed that syringaldehyde nicely interacted with glucagon-like peptide 1 receptor (GLP-1R), peroxisome proliferator-activated receptor (PPAR), dipeptidyl peptidase-IV (DPP-4), acetylcholine M2 receptor, and acetylcholinesterase. These results showed that syringaldehyde can potentiate intestinal contractility to abolish the α-amylase reaction when concurrently reducing retention time and glucose absorption to achieve a glucose-lowering effect in diabetic mice, suggesting its potential therapeutic benefits with improvement for use as a prophylactic and treatment.

Clinical potentials of ginseng polysaccharide for treating gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is the most common glucose metabolism complication or cause of potential impaired glucose tolerance that can occur either before or during pregnancy and lactation. The prevalence of GDM and its related complications in young women is increasing, and this condition may cause serious outcomes and health hazards to the foetus. However, traditional oral hypoglycaemic drugs have potential safety hazards; therefore, it is urgent to develop new, safe, effective, and easily administered agents and remedies. Ginseng polysaccharide (GPS), which is isolated from Panax (P.) ginseng C. A. Meyer, exhibits notably promising biological activities and effects; specifically, it has been shown to lower blood glucose with mild, safe, and nontoxic characteristics, and it can also improve human bodily functions. Hence, we hypothesise that GPS might be used as an additional therapy and candidate agent for treating GDM. This review innovatively summarizes the available reports and evidence from basic studies to analyze the potential for and feasibility of using GPS as a new therapeutic agent for treating GDM. Additionally, for the first time, this review provides a rationale for the use of GPS. Our summarized results show that GPS may be developed as a novel antidiabetic drug and a remedy for use in preventing and treating GDM, with great application prospects.

Prominent and emerging anti-diabetic molecular targets

Diabetes is on the rise across the globe affecting more than 463 million people and crucially increasing morbidities of diabetes-associated diseases. Urgent and immense actions are needed to improve diabetes prevention and treatment. Regarding the correlation of diabetes with many associated diseases, inhibition of the disease progression is more crucial than controlling symptoms. Currently, anti-diabetic drugs are accompanied by undesirable side-effects and target confined types of biomolecules. Thus, extensive research is demanding to identify novel disease mechanisms and molecular targets as probable candidates for effective treatment of diabetes. This review discusses the conventional molecule targets that have been applied for their therapeutic rationale in treatment of diabetes. Further, the emerging and prospective molecular targets for the future focus of library screenings are presented.

Nutraceutical characteristics of the brown seaweed carotenoid fucoxanthin

Fucoxanthin (Fx), a major carotenoid found in brown seaweed, is known to show a unique and wide variety of biological activities. Upon absorption, Fx is metabolized to fucoxanthinol and amarouciaxanthin, and these metabolites mainly accumulate in visceral white adipose tissue (WAT). As seen in other carotenoids, Fx can quench singlet oxygen and scavenge a wide range of free radicals. The antioxidant activity is related to the neuroprotective, photoprotective, and hepatoprotective effects of Fx. Fx is also reported to show anti-cancer activity through the regulation of several biomolecules and signaling pathways that are involved in either cell cycle arrest, apoptosis, or metastasis suppression. Among the biological activities of Fx, anti-obesity is the most well-studied and most promising effect. This effect is primarily based on the upregulation of thermogenesis by uncoupling protein 1 expression and the increase in the metabolic rate induced by mitochondrial activation. In addition, Fx shows anti-diabetic effects by improving insulin resistance and promoting glucose utilization in skeletal muscle.

A review on the potential of Resveratrol in prevention and therapy of diabetes and diabetic complications

Diabetes mellitus (DM) is a major world health problem and one of the most studied diseases, which are highly prevalent in the whole world, it is frequently associated with severe clinical complications, such as diabetic cardiomyopathy, nephropathy, retinopathy, neuropathy etc. Scientific research is continuously casting about for new monomer molecules from Chinese herbal medicine that could be invoked as candidate drugs for fighting against diabetes and its complications. Resveratrol (RES), a polyphenol phytoalexin, possesses diverse biochemical and physiological actions, including antiplatelet, estrogenic, and anti-inflammatory properties. It is recently gaining scientific interest for RES in controlling blood sugar and fighting against diabetes and its complications properties in various types of diabetic models. These beneficial effects seem to be due to the multiple actions of RES on cellular functions, which make RES become a promising molecule for the treatment of diabetes and diabetic complications. Here, we review the mechanism of action and potential therapeutic use of RES in prevention and mitigation of these diseases in recent ten years to provide a reference for further research and development of RES.

Anti-diabetic and renoprotective effects of Cassiae Semen extract in the streptozotocin-induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cassiae Semen, the dried seed of Cassia obtusifolia L. (Leguminosae), is a traditional Chinese medicine. It has long been used as the treatment of diabetic hyperlipidemia and diabetic constipation in Traditional Chinese Medicine formulae.

AIM OF THE STUDY

The present study was designed to investigate the anti-diabetic and renoprotective effects of Cassiae Semen extract (CSE) in streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

Quality control of CSE was performed using HPLC. CSE were orally administered at 27, 54 and 81 mg/kg dose to high-sucrose-high-fat (HSHF) diet and STZ-induced diabetic rats for 60 days. Body weight, glucose metabolism and lipid metabolism profiles were measured to assess the anti-diabetic effect of CSE. Oxidative stress markers and inflammatory factors were determined using commercial kits. Renal function related parameters were also measured. Histopathological examination of kidney was conducted for the validation of pathological changes in the diabetic rats. Immunohistochemical examination of kidney was measured to investigate the expression of RAGE in renal tissues.

RESULTS

Five compounds, including two anthraquinones and three naphtopyrones were simultaneously determined in CSE. Compared with diabetic control, groups treated with CSE exhibited an anti-diabetic effect, including a significant amelioration in body weight, glycemic control, oral glucose tolerance and lipid metabolism (P < 0.01). Moreover, oxidative stress and inflammatory responses decreased after oral administration of CSE (P < 0.01). CSE also showed protective effects on renal functions, decreasing the ratio of kidney/body weight, 24 h urine volume, 24 h urine protein, serum creatinine (Scr) and blood urea nitrogen (BUN) (P < 0.01). Additionally, renal protective effect was also observed in histopathological examination. Immunohistochemical analysis showed that CSE downregulated the expression of RAGE.

CONCLUSIONS

It turned out that CSE had both anti-diabetic and renoprotective effects in diabetic rats. CSE can be a potential agent in the treatment of type 2 diabetes mellitus (T2DM) and its complications.

Contribution of momilactones A and B to diabetes inhibitory potential of rice bran: Evidence from in vitro assays

This study was the first to detect the presence of the two compounds momilactone A (MA) and momilactone B (MB) in rice bran using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). By in vitro assays, both MA and MB exhibited potent inhibitory activities on pancreatic α-amylase and α-glucosidase which were significantly higher than γ-oryzanol, a well-known diabetes inhibitor. Remarkably, MA and MB indicated an effective inhibition on trypsin with the IC₅₀ values of 921.55 and 884.03 µg/mL, respectively. By high-performance liquid chromatography (HPLC), quantities of MA (6.65 µg/g dry weight) and MB (6.24 µg/g dry weight) in rice bran were determined. Findings of this study revealed the α-amylase, α-glucosidase and trypsin inhibitors MA and MB contributed an active role to the diabetes inhibitory potential of rice bran.

Anti-Diabetic and Anti-Nephritic Activities of Grifola frondosa Mycelium Polysaccharides in Diet-Streptozotocin-Induced Diabetic Rats Via Modulation on Oxidative Stress

Grifola frondosa is an edible fungus with a variety of potential pharmacological activities. This study investigates the hypoglycemic, anti-diabetic nephritic, and antioxidant properties of G. frondosa polysaccharides in diet-streptozotocin-induced diabetic rats. After a 4-week treatment with 100 mg/kg of metformin and 200 mg/kg of one of four different G. frondosa polysaccharide mixtures (especially GFPS3 and GFPS4), diabetic rats had enhanced body weight and suppressed plasma glucose, indicating the hypoglycemic activities of the G. frondosa polysaccharides. G. frondosa polysaccharides regulated the level of serum creatinine, blood urea nitrogen, N-acetyl-β-D-glucosaminidase, and albuminuria; inhibited the serum levels of interleukin (IL)-2, IL-6, and TNF-α; and enhanced the serum levels of matrix metalloproteinase 9 and interferon-α, confirming their anti-diabetic nephritic activities. G. frondosa polysaccharides ameliorated the pathological alterations in the kidneys of diabetic rats. Moreover, G. frondosa polysaccharides modulated the serum levels of oxidant factors such as superoxide dismutase, glutathione peroxidase, catalase, malondialdehyde, and reactive oxygen species, revealing their antioxidant properties. Furthermore, the administration of G. frondosa polysaccharides inhibited nuclear factor kappa B activities in the serum and kidneys. All of the data revealed that the activation of nuclear factor kappa B plays a central role in G. frondosa polysaccharide-mediated anti-diabetic and anti-nephritic activities.

Current anti-diabetic agents and their molecular targets: A review

Diabetes mellitus is a medical condition characterized by the body's loss of control over blood sugar. The frequency of diagnosed cases and consequential increases in medical costs makes it a rapidly growing chronic disease that threatens human health worldwide. In addition, its unnerving statistical projections are perilous to both the economy of the nation and man's life expectancy. Type-I and type-II diabetes are the two clinical forms of diabetes mellitus. Type-II diabetes mellitus (T2DM) is illustrated by the abnormality of glucose homeostasis in the body, resulting in hyperglycemia. Although significant research attention has been devoted to the development of diabetes regimens, which demonstrates success in lowering blood glucose levels, their efficacies are unsustainable due to undesirable side effects such as weight gain and hypoglycemia. Over the years, heterocyclic scaffolds have been the basis of anti-diabetic chemotherapies; hence, in this review we consolidate the use of bioactive scaffolds, which have been evaluated for their biological response as inhibitors against their respective anti-diabetic molecular targets over the past five years (2012-2017). Our investigation reveals a diverse target set which includes; protein tyrosine phosphatase 1 B (PTP1B), dipeptidly peptidase-4 (DPP-4), free fatty acid receptors 1 (FFAR1), G protein-coupled receptors (GPCR), peroxisome proliferator activated receptor-γ (PPARγ), sodium glucose co-transporter-2 (SGLT2), α-glucosidase, aldose reductase, glycogen phosphorylase (GP), fructose-1,6-bisphosphatase (FBPase), glucagon receptor (GCGr) and phosphoenolpyruvate carboxykinase (PEPCK). This review offers a medium on which future drug design and development toward diabetes management may be modelled (i.e. optimization via structural derivatization), as many of the drug candidates highlighted show promise as an effective anti-diabetic chemotherapy.

Bioactive polyphenols in kinkéliba tea (Combretum micranthum) and their glucose-lowering activities

Herbal tea kinkéliba prepared from the leaves of Combretum micranthum has been widely consumed in West African countries for its flavor, nutritional and medicinal properties. Under bio-guided screening, the kinkéliba leaves were chemically investigated using various chromatographic and spectrometric methods that led to the identification of thirteen different flavonoid compounds. Further biological tests illustrated that the identified compounds may have synergistic effects to decrease the expression of phosphoenolpyruvate carboxykinase (PEPCK) mRNA and glucose production in an H4IIE hepatoma cell line, indicating its potential use for insulin-resistant diabetes treatment. Further in vivo study on C57BL/6J mice indicates that kinkéliba can lower plasma glucose levels in a dose-dependent manner without significant weight loss and toxicity. The ethyl acetate extract in rich of flavonoids could also increase the glucose tolerance (GT) after seven weeks' administrations. Both in vitro and in vivo experiments support a potential new application of kinkéliba leaves as an anti-diabetes agent.

Raffinose from Costus speciosus attenuates lipid synthesis through modulation of PPARs/SREBP1c and improves insulin sensitivity through PI3K/AKT

Among several metabolic disorders, the pathogenesis of insulin resistance is considered to be multifactorial. Raffinose, an oligosaccharide isolated from the rhizome of Costus speciosus showed ≤50% inhibition of lipid accumulation in differentiated HepG2 and 3T3-L1 cells through exhibiting partial agonism to PPARγ, and, an enhanced secretion of adiponectin in 3T3-L1 adipocytes. Raffinose was also observed to attenuate the expression of SREBP1c, ACC and FAS which are involved in the fatty acid synthesis. A corresponding upregulation of PPARα and ACO involved in fatty acid oxidation was observed in steatotic HepG2 hepatocytes and 3T3-L1 adipocytes. In vitro evaluation of its anti-diabetic potential showed a dose dependent enhancement of glucose uptake. Investigation of the insulin sensitizing efficacy of Raffinose revealed an increase in Glut4 translocation via phosphorylation of IRβ/PI3K/Akt in differentiated L6 myocytes and 3T3-L1 preadipocytes. In addition, Raffinose was potentially involved in glycogen synthesis by inhibiting the activation of GSK3β. Hence, Raffinose could be a useful therapeutic agent for metabolic maladies.

Anti-diabetic effects of Inonotus obliquus polysaccharides-chromium (III) complex in type 2 diabetic mice and its sub-acute toxicity evaluation in normal mice

Polysaccharides are important bioactive ingredients from Inonotus obliquus. This study aimed to synthesize and characterize a novel I. obliquus polysaccharides-chromium (III) complex (UIOPC) and investigate the anti-diabetic effects in streptozotocin (STZ) induced type 2 diabetes mellitus (T2DM) mice and sub-acute toxicity in normal mice. The molecular weight of UIOPC was about 11.5 × 10 ⁴ Da with the chromium content was 13.01% and the chromium was linked with polysaccharides through coordination bond. After treatment of UIOPC for four weeks, the body weight, fasting blood glucose (FBG) levels, plasma insulin levels of the diabetic mice were significantly reduced when compared with those of the diabetic mice (p < 0.05). The results on serum profiles and antioxidant enzymes activities revealed that UIOPC had a positive effect on hypoglycemic and antioxidant ability. Histopathology results showed that UIOPC could effectively alleviate the STZ-lesioned tissues in diabetic mice. Furthermore, high dose administration of UIOPC had no obviously influence on serum profiles levels and antioxidant ability of the normal mice and the organ tissues maintained organized and integrity in the sub-acute toxicity study. These results suggested that UIOPC might be a good candidate for the functional food or pharmaceuticals in the treatment of T2DM.

Larix laricina bark, a traditional medicine used by the Cree of Eeyou Istchee: Antioxidant constituents and in vitro permeability across Caco-2 cell monolayers

ETHNOPHARMACOLOGICAL RELEVANCE

Larix laricina, a native tree of North America, is a highly respected medicinal plant used for generations by Indigenous Peoples across its range, including the Cree of northern Québec who use the bark to treat symptoms of diabetes. This study investigates the antioxidant capacity and bioavailability of active constituents identified in L. laricina bark extracts.

MATERIALS AND METHODS

(1) Oxygen radical absorbance capacity (ORAC) assay was employed to test antioxidant capacity of organic extracts (80% ethanol) from bark of L. laricina as well as fractions, isolated compounds, and media samples collected during permeability assays. (2) Caco-2 cell monolayer cultures were used to determine the permeability of identified antioxidants, which were quantified in basolateral media samples using liquid chromatography - tandem mass spectrometry (HPLC-ESI-MS/MS).

RESULTS

Crude ethanolic extract possessed strong antioxidant potential in vitro (7.1±0.3 Trolox equivalents (TE) μM/mg). Among the 16 L. laricina fractions obtained by chromatographic separation, fraction 10 (F10) showed the highest antioxidant capacity (21.8±1.7µm TE/mg). Among other identified antioxidants, the stilbene rhaponticin (isolated from F10) was the most potent (24.6±1.1µm TE/mg). Caco-2 transport studies revealed that none of the identified compounds were detectable in basolateral samples after 2-h treatment with crude extract. In monolayers treated with F10 (60% rhaponticin), small quantities of rhaponticin were increasingly detected over time in basolateral samples with an apparent permeability coefficient (P_app) of 1.86×10^-8cm/s (0-60min). To model potential effects on blood redox status, we evaluated the antioxidant capacity of collected basolateral samples and observed enhanced activity over time after exposure to both extract and F10 (75μg/mL) relative to control.

CONCLUSIONS

By profiling the antioxidant constituents of L. laricina bark, we identified rhaponticin as the most potent oxygen radical scavenger and observed low permeability in Caco-2 cell monolayers but an increase in basolateral antioxidant capacity.

Evaluation of extraction protocols for anti-diabetic phytochemical substances from medicinal plants

AIM

To examine the efficacy of three extraction techniques: Soxhlet-extraction (SE), cold-maceration (CM) and microwave-assisted-extraction (MAE) using 80% methanol as solvent.

METHODS

The study was performed on each of 50 g of Vernonia amygdalina (VA) and Occimum gratissimum (OG) leaves respectively. The percentage yield, duration of extraction, volume of solvent used, qualitative and quantitative phytoconstituents present was compared. The biological activities (hypoglycemic effect) were investigated using albino wistar rat model of diabetes mellitus (n = 36) with a combined dose (1:1) of the two plants leaf extracts (250 mg/kg b.w.) from the three methods. The extracts were administered orally, once daily for 21 d.

RESULTS

In this report, the percentage VA extract yield from MAE was highest (20.9% ± 1.05%) within 39 min using 250 mL of solvent, when compared to the CM (14.35% ± 0.28%) within 4320 min using 900 mL of solvent and SE (15.75% ± 0.71%) within 265 min using 500 mL of solvent. The percentage differences in OG extract yield between: MAE vs SE was 41.05%; MAE vs CM was 46.81% and SE vs CM was 9.77%. The qualitative chemical analysis of the two plants showed no difference in the various phytoconstituents tested, but differs quantitatively in the amount of the individual phytoconstituents, as MAE had significantly high yield (P > 0.05) on phenolics, saponins and tannins. SE technique gave significantly high yield (P > 0.05) on alkaloid, while CM gave significant high yield on flavonoids. The extracts from CM exhibited a significantly (P > 0.05) better hypoglycemic activity within the first 14-d of treatment (43.3% ± 3.62%) when compared to MAE (36.5% ± 0.08%) and SE methods (33.3% ± 1.60%). However, the percentage hypoglycemic activity, 21 d post-treatment with 250 mg/kg b.w. extract from MAE was 72.6% ± 1.03% and it was more comparable to 10 mg/kg b.w. glibenclamide treated group (75.0% ± 0.73%), unlike the SE (69.5% ± 0.71%) and CM (69.1% ± 1.03%).

CONCLUSION

CM technique produces extract with better hypoglycemic activity, whereas; MAE is a better option for high yield of phytoconstituents using less solvent within a short time.

In vitro α-glucosidase inhibitory activity of isolated fractions from water extract of Qingzhuan dark tea

BACKGROUND

Natural products have being used as potential inhibitors against carbohydrate-hydrolyzing enzymes to treat diabetes mellitus. Chinese dark tea has various interesting bioactivities. In this study, the active compounds from Qingzhuan dark tea were separated and their anti-diabetic activity was examined using an in vitro enzymatic model.

METHODS

The chloroform, ethyl acetate, n-butanol, sediment and residual aqua fractions of a Chinese dark tea (Qingzhuan tea) were prepared by successively isolating the water extract with different solvents and their in vitro inhibitory activities against α-glucosidase were assessed. The fraction with the highest inhibitory activity was further characterized to obtain the main active components of Qingzhuan tea.

RESULTS

The ethyl acetate fraction had the greatest inhibitory effect on α-glucosidase, followed by n-butanol, sediment and residual aqua fractions (with the IC₅₀ values of 0.26 mg/mL, 2.94 mg/mL, 3.02 mg/mL, and 5.24 mg/mL, respectively), mainly due to the high content of polyphenols. Among the eight subfractions (QEF1-8) isolated from the ethyl acetate fraction, QEF8 fraction showed the highest α-glucosidase inhibitory potential in a competitive inhibitory manner (the K _i value of 77.10 μg/mL). HPLC-MS analysis revealed that (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG) were the predominant active components in QEF8.

CONCLUSION

These results indicated that Qingzhuan tea extracts exerted potent inhibitory effects against α-glucosidase, EGCG and ECG were likely responsible for the inhibitory activity in Qingzhuan tea. Qingzhuan tea may be recommended as an oral antidiabetic diet.

Anti-adipogenic and anti-diabetic effects of cis-3',4'-diisovalerylkhellactone isolated from Peucedanum japonicum Thunb leaves in vitro

Peucedanum japonicum Thunb is a medicinal plant belonging to the family Umbelliferae. This study evaluated the anti-diabetic and anti-obesity effects of cis-3',4'-diisovalerylkhellactone (cDIVK) isolated from Peucedanum japonicum Thunb leaves. cDIVK (30 and 50μM) effectively inhibited adipocyte differentiation and fat accumulation, whereas it stimulated glucose uptake compared with the control in 3T3-L1 cells. cDIVK significantly increased AMPK activation and suppressed protein and mRNA expression of major adipogenic transcriptional factors such as C/EBPα, PPARγ and SREBP-1c in 3T3-L1 cells. In addition, cDIVK had potential α-glucosidase inhibitory activity. These results indicated that cDIVK may act as a natural dual therapeutic agent for diabetes and obesity.

A novel α-glucosidase inhibitory constituent from Uncaria gambir

Bioactivity-guided fractionation of an aqueous methanolic extract of manufactured gambir product from Uncaria gambir with in vitro α-glucosidase inhibitory activity was performed to isolate a novel prenyl resorcinol derivative (1) together with seven known compounds, including two flavone glycosides (2, 3), three catechin analogues (4-6), and two simple phenolics (7, 8). Structures of the isolated compounds were determined by analysis of physical and spectroscopic data (NMR, UV, [α]D, and MS). All isolates were evaluated for in vitro α-glucosidase inhibitory activity. Among the compounds, novel compound 1, possessing an unprecedented spirocyclopropane ring in the molecule, showed the most potent α-glucosidase inhibitory activity in this assay. On the other hand, compounds 4 and 7 showed less potent inhibitory effects in this same bioassay, with half-maximal inhibitory concentration values of 17.3 ± 1.0 μM and 27.0 ± 0.9 μM, respectively.

Phytochemical distribution in hull and cotyledon of adzuki bean (Vigna angularis L.) and mung bean (Vigna radiate L.), and their contribution to antioxidant, anti-inflammatory and anti-diabetic activities

Total saponin content, total phenolics content, total flavonoids content, condensed tannin content in hull, cotyledon and whole grain of both adzuki bean and mung bean were determined by colorimetric methods. Vitexin and isovitexin contents in mung bean were determined by HPLC. Antioxidant effects were evaluated with DPPH scavenging activity and ferric reducing antioxidant power assay. In vitro anti-inflammatory and anti-diabetic effects of beans were evaluated by protease and aldose reductase inhibitory assays, respectively. The results indicated that the bean hulls were the most abundant in phytochemicals and largely contributed antioxidant activities, anti-inflammatory effects and anti-diabetic effects of whole grains. The result showed that mung bean hull was the most abundant with vitexin at 37.43 mg/g and isovitexin at 47.18 mg/g, respectively. Most of the phytochemicals and bioactivities were most predominantly contributed by the bean hulls with exception for condensed tannin of mung bean; which was more abundant in the cotyledon than its hull.

Anti-obesity and anti-diabetic effects of flavonoid derivative (Fla-CN) via microRNA in high fat diet induced obesity mice

3-O-[(E)-4-(4-cyanophenyl)-2-oxobut-3-en-1-yl]kaempferol (Fla-CN), a semi-synthesized flavonoid derivative of tiliroside, reduces whole-body adiposity, ameliorates metabolic lipid disorder, improves insulin sensitivity and benefits other disorders characterized by insulin resistance in high fat diet induced obesity mice. The improvement of insulin sensitivity and the reduction of weight gain are correlated with the changes of leptin and adiponectin levels. As a result, Fla-CN treatment could increase the expressions of pAMPK and miR-27 in the liver and adipose tissues. Meanwhile, we discovered that the expressions of various adipogenesis genes were downregulated, which were target genes of miR-27. This is the first report for the action of miR-27 by flavonoid derivative in rodents. The action of Fla-CN might be through multiple approaches including AMPK activation and enhancement in miR-27 expression.

Novel benzothiazinones (BTOs) as allosteric modulator or substrate competitive inhibitor of glycogen synthase kinase 3β (GSK-3β) with cellular activity of promoting glucose uptake. Bioorg Med Chem Lett. 2014;24:5639-5643. [PMID: 25467150 DOI: 10.1016/j.bmcl.2014.10.078]

Glycogen synthase kinase 3β (GSK-3β) plays a key role in insulin metabolizing pathway and therefore inhibition of the enzyme might provide an important therapeutic approach for treatment of insulin resistance and type 2 diabetes. Recently, discovery of ATP noncompetitive inhibitors is gaining importance not only due to their generally increased selectivity but also for the potentially subtle modulation of the target. These kinds of compounds include allosteric modulators and substrate competitive inhibitors. Here we reported two benzothiazinone compounds (BTO), named BTO-5h (IC50=8 μM) and BTO-5s (IC50=10 μM) as novel allosteric modulator and substrate competitive inhibitor of GSK-3β, respectively. Their different action modes were proved by kinetic experiments. Furthermore, BTO-5s was selected to check the kinases profile and showed little or even no activity to a panel of ten protein kinases at 100 μM, indicating it has good selectivity. Docking studies were performed to give suggesting binding modes which can well explain their impacts on the enzyme. Moreover, cell experiments displayed both compounds reduced the phosphorylation level of glycogen synthase in an intact cell, and greatly enhanced the glucose uptake in both HpG2 and 3T3-L1 cells. All of these results suggested BTO-5s and BTO-5h maybe have potentially therapeutic value for anti-diabetes. The results also offer a new scaffold for designing and developing selective inhibitors with novel mechanisms of action.

Chemical constituents and pharmacologic actions of Cynomorium plants

The stem of Cynomorium songaricum is a traditional Chinese medicine reputed to have tonic effects. C. coccineum growing in northern Africa and the Mediterranean region is regarded in Arabian medical practice as the "treasure of drugs". The major constituents of Cynomorium plants have been revealed to be phenolic compounds, steroids, triterpenes, etc. Pharmacologic studies showed that the Cynomorium plants had antioxidant, immunity-improving, anti-diabetic, neuroprotective, and other bioactivities. Some chemical constituents in Cynomorium plants are unstable, implying that the chemical components of the herbal medicines produced under different conditions may be variable. This review covers the literature published until December, 2011 and describes the pharmacologic effects and secondary metabolites of Cynomorium species.

Chemical constituents and pharmacologic actions of Cynomorium plants

The stem of Cynomorium songaricum is a traditional Chinese medicine reputed to have tonic effects. C. coccineum growing in northern Africa and the Mediterranean region is regarded in Arabian medical practice as the "treasure of drugs". The major constituents of Cynomorium plants have been revealed to be phenolic compounds, steroids, triterpenes, etc. Pharmacologic studies showed that the Cynomorium plants had antioxidant, immunity-improving, anti-diabetic, neuroprotective, and other bioactivities. Some chemical constituents in Cynomorium plants are unstable, implying that the chemical components of the herbal medicines produced under different conditions may be variable. This review covers the literature published until December, 2011 and describes the pharmacologic effects and secondary metabolites of Cynomorium species.

3-Amino-N-adamantyl-3-methylbutanamide derivatives as 11β-hydroxysteroid dehydrogenase 1 inhibitor

Many adamantane derivatives have been demonstrated to function as 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) inhibitors. 3-Amino-N-adamantyl-3-methylbutanamide derivatives were optimized by structure-based drug design. Compound 8j exhibited a good in vitro and ex vivo inhibitory activity against both human and mouse 11β-HSD1.

Antidiabetic effects of Swertia macrosperma extracts in diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Swertia macrosperma is a traditional folk medicine used for its anti-hepatitis, antipyretic and antidotal effects as "Dida" or "Zangyinchen" in Tibet, Yunnan and Guizhou province for a long time, and it has been reported for its anti-diabetic effects in a Chinese patent. Swertia macrosperma was reported rich in xanthones, iridoids, seco-iridoids and their glycosides, several of which had been documented as potential antidiabetic agents. The objective of this study was to investigate the antidiabetic effect of Swertia macrosperma in diabetic rats.

MATERIALS AND METHODS

This study was designed firstly to evaluate the effect of Swertia macrosperma on glucose consumption in HepG2 cells. Based on the result in HepG2 cells, the antidiabetic effect of ethanol extract (EE) and n-butanol extract (BE) were investigated in diabetic rats induced by high fat fed and streptozotocin. The effects of EE and BE on fasting blood glucose, oral glucose tolerance test, serum insulin, glycosylated hemoglobin, serum lipid level, serum antioxidant parameters, glucokinase, glucose-6-phosphatase activities and glycogen content in liver tissue were measured, histology examination of pancreatic tissue was also carried out.

RESULTS

After 4 weeks treatment with EE and BE, apparently decreased fasting blood glucose concentrations were observed in these treated groups, compared with the diabetic control groups. Additionally, improvement in serum antioxidant parameters and lipid profile were evidenced clearly. Moreover, EE and BE had effects of protecting the pancreatic β-cells and stimulating insulin secretion from the remaining pancreatic β-cells, evidenced by pancreatic histology examination. Increased glucokinase activity and decreased glucose-6-phosphatase activity were observed in liver.

CONCLUSION

The results of in vivo and in vitro experiment suggested that EE and BE of Swertia macrosperma had excellent effects on controlling the hyperglycemia and hyperlipidemia in diabetic rats.

Ethanol extract of the Prunus mume fruits stimulates glucose uptake by regulating PPAR-γ in C2C12 myotubes and ameliorates glucose intolerance and fat accumulation in mice fed a high-fat diet

In this study, we performed in vitro and in vivo studies to examine whether a 70% ethanol extract of Prunus mume fruits (EMS) exhibits anti-diabetic effects. Treatment with EMS increased glucose uptake in C2C12 myotubes, and also increased PPAR-γ activity or PPAR-γ mRNA expression. To confirm these in vitro results, we next conducted an animal experiment. A high-fat diet significantly increased the body weight, fat accumulation, and glucose levels in mice. Under the same conditions, 5% EMS attenuated the high-fat diet-induced increase in body weight and fat accumulation and improved the impaired fasting glucose level and glucose tolerance. High performance liquid chromatography analysis demonstrated that EMS contained chlorogenic acid, caffeic acid, rutin, luteolin-7-glucoside, naringin, apigenin-7-glucoside, and hesperidin. Taken together, these findings suggest that EMS exerts an anti-diabetic effect both in vitro and in vivo, which is mediated, at least in part, by the activation of PPAR-γ.