Rhinacanthin C ameliorates hyperglycaemia, hyperlipidemia and pancreatic destruction in streptozotocin–nicotinamide induced adult male diabetic rats

α-amylase inhibition and in silico studies of novel naphtho[2,3-d]imidazole-4,9-dione linked N-acyl hydrazones

Aim: To enrich the pool of α-amylase inhibitors to manage Type 2 diabetes. Methods: Synthesis, conformational study, α-amylase inhibitory action and various in silico studies of novel N'-(arylbenzylidene)-2-(4,9-dioxo-4,9-dihydro-1H-naphtho[2,3-d]imidazol-1-yl)acetohydrazides carried out. Results: Compound H6 demonstrated the highest activity (IC50 = 0.0437 μmol mL-1) among the tested compounds. Structure-activity relationship study suggested that variable substitution at the aryl ring has a pivotal role in determining the inhibitory action of tested compounds. Docking simulations of the most active compound (H6) confirmed its interaction potential with active site residues of A. oryzae α-amylase. The root-mean-square deviation fluctuations substantiated the stability of protein-ligand complex. Absorption, distribution, metabolism and excretion prediction revealed optimal values for absorption, distribution, metabolism and excretion parameters. Conclusion: The developed molecules could be beneficial for the development of novel α-amylase inhibitors to treat Type 2 diabetes.

Design, synthesis, spectroscopic characterization, single crystal X-ray analysis, in vitro α-amylase inhibition assay, DPPH free radical evaluation and computational studies of naphtho[2,3-d]imidazole-4,9-dione appended 1,2,3-triazoles

In our quest to design and develop N/O-containing inhibitors of α-amylase, we have tried to synergize the inhibitory action of 1,4-naphthoquinone, imidazole and 1,2,3-triazole motifs by incorporating these structures into a single matrix. For this, a series of novel naphtho[2,3-d]imidazole-4,9-dione appended 1,2,3-triazoles is synthesized by a sequential approach involving [3 + 2] cycloaddition of 2-aryl-1-(prop-2-yn-1-yl)-1H-naphtho[2,3-d]imidazole-4,9-diones with substituted azides. The chemical structures of all the compounds are established with the help of 1D-NMR, 2D-NMR, IR, mass and X-ray studies. The developed molecular hybrids are screened for their inhibitory action on the α-amylase enzyme using the reference drug, acarbose. Different substituents present on the attached aryl part of the target compounds show amazing variations in inhibitory action against the α-amylase enzyme. Based on the type of substituents and their respective positions, it is observed that compounds containing -OCH₃ and -NO₂ groups show more inhibition potential than others. All the tested derivatives display α-amylase inhibitory activity with IC₅₀ values in the range of 17.83 ± 0.14 to 26.00 ± 0.17 μg/mL. Compound 2-(2,3,4-trimethoxyphenyl)-1-{[1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl]methyl}-1H-naphtho[2,3-d]imidazole-4,9-dione (10y) show maximum inhibition of amylase activity with IC₅₀ value 17.83 ± 0.14 μg/mL as compared to reference drug acarbose (18.81 ± 0.05 μg/mL). A molecular docking study of the most active derivative (10y) is performed with A. oryzae α-amylase (PDB ID: 7TAA) and it unveils favourable binding interactions within the active site of the receptor molecule. The dynamic studies reveal that the receptor-ligand complex is stable as the RMSD of less than 2 is observed in 100 ns molecular dynamic simulation. Also, the designed derivatives are assayed for their DPPH free radical scavenging ability and all of them exhibit comparable radical scavenging activity with the standard, BHT. Further, to assess their drug-likeness properties, ADME properties are also evaluated and all of them demonstrate worthy in silico ADME results.

Thiazolidinedione Derivatives: In Silico, In Vitro, In Vivo, Antioxidant and Anti-Diabetic Evaluation

This work aimed to synthesize a new antihyperglycemic thiazolidinedione based on the spectral data. The DFT\B3LYP\6-311G** level of theory was used to investigate the frontier molecular orbitals (FMOs), chemical reactivity and map the molecular electrostatic potentials (MEPs) to explain how the synthesized compounds interacted with the receptor. The molecular docking simulations into the active sites of PPAR-γ and α-amylase were performed. The in vitro potency of these compounds via α-amylase and radical scavenging were evaluated. The data revealed that compounds (4–6) have higher potency than the reference drugs. The anti-diabetic and anti-hyperlipidemic activities for thiazolidine-2,4-dione have been investigated in vivo using the alloxan-induced diabetic rat model along with the 30 days of treatment protocol. The investigated compounds didn’t show obvious reduction of blood glucose during pre-treatments compared to diabetic control, while after 30 days of treatments, the blood glucose level was lower than that of the diabetic control. Compounds (4–7) were able to regulate hyperlipidemia levels (cholesterol, triglyceride, high-density lipoproteins and low- and very-low-density lipoproteins) to nearly normal value at the 30th day.

Investigation of the Effects of L-carnitine and magnesium on Oxidative Stress and Cytokines in the Tissue of Experimental diabetic rats

The aim of this study was to determine the effects of L-carnitine and magnesium on the levels of tissue malondialdehyde, 8-hydroxy-2’-deoxyguanosine, and cytokines (tumor necrosis factor alpha, interleukin-6) in streptozotocin-induced experimental diabetes in rats. Eighty male Wistar albino rats (200-250 g) were divided into 8 groups with 10 rats in each group. The groups received the following treatments: Control group; 2 ml distilled water (by gavage); Group 2: 50 mg/kg (b.w.) i.p. streptozotocin; Group 3: 125 mg/kg (b.w.) magnesium; Group 4: 300 mg/kg (b.w.) L-carnitine; Group 5: 125 mg/kg (b.w.) magnesium +300 mg/kg (b.w.) L-carnitine; Group 6: 50 mg/kg (b.w.) streptozotocin +125 mg/kg (b.w.) magnesium; Group 7: 50 mg/kg (b.w.) streptozotocin +300 mg/kg (b.w.) L-carnitine and Group 8: 50 mg/kg (b.w.) streptozotocin +125 mg/ kg (b.w.) magnesium+300 mg/kg (b.w.) L-carnitine administered for 4 weeks. Liver and kidney malondialdehyde, 8-hydroxy-2’-deoxyguanosine, tumor necrosis factor alpha and interleukin-6 levels did not change in the magnesium, L-carnitine, and magnesium + L-carnitine groups compared to the control. The highest levels of malondialdehyde, 8-hydroxy-2’-deoxyguanosine, tumor necrosis factor alpha and interleukin-6 were determined only in the group with diabetes (Group 2). Lipid peroxidation, DNA damage, and cytokine levels were significantly reduced in diabetic animals with the administration of magnesium and L-carnitine separately or in combination. Based on the obtained results it can be concluded that magnesium and L-carnitine may have antidiabetic effects, especially in combination.

Discovery Potent of Thiazolidinedione Derivatives as Antioxidant, α-Amylase Inhibitor, and Antidiabetic Agent

This work aimed to synthesize safe antihyperglycemic derivatives bearing thiazolidinedione fragment based on spectral data. The DFT theory discussed the frontier molecular orbitals (FMOs), chemical reactivity of compounds, and molecular electrostatic potential (MEP) to explain interaction between thiazolidinediones and the biological receptor. α-amylase is known as the initiator-hydrolysis of the of polysaccharides; therefore, developing α-amylase inhibitors can open the way for a potential diabetes mellitus drug. The molecular docking simulation was performed into the active site of PPAR-γ and α-amylase. We evaluated in vitro α-amylase's potency and radical scavenging ability. The compound 6 has the highest potency against α-amylase and radical scavenging compared to the reference drug and other members. They have been applied against anti-diabetic and anti-hyperlipidemic activity (in vivo) based on an alloxan-induced diabetic rat model during a 30-day treatment protocol. The most potent anti hyperglycemic members are 6 and 11 with reduction percentage of blood glucose level by 69.55% and 66.95%, respectively; compared with the normal control. Other members exhibited moderate to low anti-diabetic potency. All compounds showed a normal value against the tested biochemical parameters (CH, LDL, and HDL). The ADMET profile showed good oral bioavailability without any observed carcinogenesis effect.

Rhinacanthus nasutus "Tea" Infusions and the Medicinal Benefits of the Constituent Phytochemicals

Rhinacanthus nasutus (L.) Kurz (Acanthaceae) (Rn) is an herbaceous shrub native to Thailand and much of South and Southeast Asia. It has several synonyms and local or common names. The root of Rn is used in Thai traditional medicine to treat snake bites, and the roots and/or leaves can be made into a balm and applied to the skin for the treatment of skin infections such as ringworm, or they may be brewed to form an infusion for the treatment of inflammatory disorders. Rn leaves are available to the public for purchase in the form of “tea bags” as a natural herbal remedy for a long list of disorders, including diabetes, skin diseases (antifungal, ringworm, eczema, scurf, herpes), gastritis, raised blood pressure, improved blood circulation, early-stage tuberculosis antitumor activity, and as an antipyretic. There have been many studies investigating the roles of Rn or compounds isolated from the herb regarding diseases such as Alzheimer’s and other neurodegenerative diseases, cancer, diabetes and infection with bacteria, fungi or viruses. There have, however, been no clinical trials to confirm the efficacy of Rn in the treatment of any of these disorders, and the safety of these teas over long periods of consumption has never been tested. This review assesses the recent research into the role of Rn and its constituent compounds in a range of diseases.

Medicinal plants utilized in Thai Traditional Medicine for diabetes treatment: Ethnobotanical surveys, scientific evidence and phytochemicals

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus remains the most lethal metabolic disease of contemporaneous times and despite the therapeutic arsenal currently available, research on new antidiabetic agents remains a priority. In recent years, the revitalization of Thai Traditional Medicine (TTM) became a clear priority for the Thai government, and many efforts have been undertaken to accelerate research on herbal medicines and their use in medical services in various hospitals. Additionally, and particularly in rural areas, treatment of diabetes and associated symptomatology frequently relies on herbal preparations recommended by practitioners of TTM. In the current work, medicinal plants used in Thailand for treating diabetes, as well as their hypoglycaemic pharmacological evidences and potential therapeutic use for diabetes-related complications were reviewed.

MATERIALS AND METHODS

Ethnopharmacological information on the plant materials used in TTM for diabetes treatment was collected through literature search in a range of scientific databases using the search terms: diabetes, folk medicine, Thailand medicinal plants, traditional medicine. Information regarding scientific evidence on the antidiabetic effects of surveyed species was obtained considering not only the most common taxonomic designation, but also taxonomic synonyms, and including the keywords 'diabetes' and 'hypoglycaemic effect'.

RESULTS

A total of 183 species known to be used for diabetes management in TTM were reviewed, with 30% of them still lacking experimental evidences to support claims regarding the mechanisms and phytochemicals underlying their antidiabetic properties. Moreover, a total of 46 bioactives displaying effective antidiabetic effects have been isolated from 24 species, their underlying mechanism(s) of action being fully or partially disclosed.

CONCLUSIONS

We deliver the most extensive survey dealing with the ethnomedicinal knowledge of Thai medicinal plants utilized on diabetes management. We are certain that the current review will spark further research on Thai plants for the development of new standardized phytomedicines through drug discovery programmes.

Pharmacokinetics, Tissue Distribution and Excretion of Paeonol and Its Major Metabolites in Rats Provide a Further Insight Into Paeonol Effectiveness

Paeonol is a major bioactive ingredient in Moutan Cortex (the root barks of Paeonia suffruticosa Andrews) and exhibited a wide range of bioactivities such as anti-inflammation, anti-oxidation, hypoglycemic effect, analgesic, and others. Even though paeonol has been proven to possess significant pharmacological and therapeutic effects, its pharmacokinetic properties are not satisfactory since it has been found to have a rapid clearance in vivo. In the present study, the pharmacokinetics, tissue distribution and excretion of paeonol and its major metabolites were investigated in rats by an efficient and specific UPLC-MS/MS method. The results indicated that paeonol was rapidly absorbed, extensively metabolized, and widely distributed in various tissues without long-term accumulation after oral administration to rats. The major distribution tissues of paeonol and its metabolites were kidney, liver, and heart. Paeonol was able to cross the blood-brain barrier but rapidly decreased after 10 min. The total excretion of four metabolites in urine, bile, and feces was approximately 35.0% within 24 h, and the metabolites were mainly excreted through the urine. In addition, the hypoglycemic activities of paeonol and its metabolites were investigated by a glucose uptake assay on TNF-α mediated insulin resistance in 3T3-L1 adipocytes. The results showed that paeonol and its major metabolites displayed hypoglycemic activities. This is the first comprehensive and systematic report on the pharmacokinetics of paeonol and its metabolites. This research provides an important basis for the clinical development and application of active metabolites.

The methanolic extract of Thymus praecox subsp. skorpilii var. skorpilii restores glucose homeostasis, ameliorates insulin resistance and improves pancreatic β-cell function on streptozotocin/nicotinamide-induced type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Thymus praecox subsp. skorpilii var. skorpilii (syn. Thymus praecox subsp. jankae (Celak.) Jalas) is consumed as a Turkish folk medicine for the treatment of spasm, sore throat and shortness of breath, also having strong antioxidant activity and the leaves of the plant have been utilized for the treatment of diabetes as the decoction in Turkey.

AIM OF THE STUDY

In the present study, we aimed to investigate the potential mechanism of antidiabetic action of Thymus praecox subsp. skorpilii var. skorpilii methanolic extract (TPSE) on streptozotocin (STZ)/nicotinamide (NA)-induced type 2 diabetic rats.

MATERIALS AND METHODS

Sprague Dawley rats were randomly divided into four groups; control, diabetes, TPSE (100 mg/kg b.w, p.o.) and metformin group (400 mg/kg b.w, p.o.). Diabetes was established in all groups except control group by 55 mg/kg STZ (i.p.) for once 15 min after 100 mg/kg NA injection. 3 days after STZ/NA injection, treatments were administered for three weeks and then rats were decapitated; tissue and blood samples were obtained for measuring the level of glucose transporters (both GLUTs and sodium glucose co-transporters (SGLTs)), enzymes related to glucose (Hexokinase (HK), phosphoenolpyruvate carboxykinase (PEPCK), α-glucosidase) and lipid metabolism (Acetyl-coenzyme carboxylase (ACC)), AST, ALT, creatinine, insulin, anti-inflammatory (IL-10) and inflammatory (TNF-α, IL-1β, IL-6) cytokines, AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor gamma (PPAR-γ) and glucagon like peptide-1 (GLP-1). Histopathological alterations of the pancreas were examined.

RESULTS

After three weeks of treatment, TPSE has exhibited a significant reduction of plasma levels of the proinflammatory cytokines. Besides, TPSE treatment elevated plasma insulin levels and normalized blood glucose levels. Moreover, it improved the values of AMPK in liver and GLP-1 in pancreas. Increased α-glucosidase, PEPCK, GLUT-2 and SGLTs levels with the induction of diabetes considerably lowered with TPSE treatment. Especially on SGLT-2, TPSE achieved a more prominent decrease. After the atrophy in Langerhans islets due to diabetes induction, treatment was found to prevent the damage of islets.

CONCLUSIONS

Based on the findings presented here, it has been concluded that TPSE has marked antidiabetic effects through various pathways on STZ/NA-induced diabetic rats and it may potentially be used as an effective treatment for type 2 diabetes mellitus (T2DM). Further research on isolation of the bioactive components is underway.

Acetylshikonin stimulates glucose uptake in L6 myotubes via a PLC-β3/PKCδ-dependent pathway

Acetylshikonin, a naphthoquinone derivative derived from Lithospermum erythrorhizon, has been shown to have various pharmacological activities; however, its effect on diabetes has rarely been reported. We investigated the hypoglycemic effect of acetylshikonin and found that it decreased blood glucose to a greater extent than insulin and improved glucose tolerance in mice. It also increased glucose uptake in L6 myotubes by inducing the expression and translocation of glucose transporter 4 via decomposition of phosphatidylinositol, increased generation of diacylglycerol, and activation of protein kinase C delta cascades; this is an insulin-, reactive oxygen species-, and AMP-activated protein kinase-independent pathway for glucose uptake. Our findings highlight the antidiabetic potential of acetylshikonin via a possible novel pathway for glucose uptake in L6 myotubes.

Rhinacanthins-rich extract and rhinacanthin C ameliorate oxidative stress and inflammation in streptozotocin-nicotinamide-induced diabetic nephropathy

In this present study, rhinacanthins-rich extract (RRE) and rhinacanthin C (RC) the main bioactive constituent of Rhinacanthus nasutus was investigated for their protective effect against diabetic nephropathy (DN). Diabetes was induced by administering nicotinamide (100 mg/kg, i.p.)/streptozotocin (60 mg/kg, i.p.) and diabetic rats were orally administered with RRE and RC for 4 weeks. RRE and RC significantly reduced the kidney index, renal oxidative stress markers, and pro-inflammatory cytokines. Furthermore, RRE and RC increased renal levels of glutathione, superoxide dismutase, catalase, and attenuated diabetic induced renal damages. In conclusion, RRE and RC confer protective effect against DN through the inhibition of oxidative stress and inflammation and could be a potential medicinal or nutritional supplement for the prevention of DN. PRACTICAL APPLICATIONS: Rhinacanthus nasutus is a medicinal plant that is extensively used in Thai traditional medicine as an antibacterial, antifungal, antidiabetic, and anti-inflammatory agent. The plant is rich in naphthoquinones, which confer it with several excellent bioactivities. The rich extract of the leaves was prepared with three major bioactive components and the extract was evaluated for its renoprotective effect in diabetic rats. The results from this study provides valuable pharmacological information that supports the use of the plant, especially the rich extract in the prevention and treatment of diabetes and diabetic complications.

In vivo administration of quercetin ameliorates sperm oxidative stress, inflammation, preserves sperm morphology and functions in streptozotocin-nicotinamide induced adult male diabetic rats

INTRODUCTION

Diabetes mellitus (DM) has been associated with sperm damage. In view of the fact that quercetin possesses antioxidant and anti-inflammatory activities, this compound may help to protect sperm against damage in DM. In this study, in-vivo effects of quercetin on sperm parameters in DM were investigated.

MATERIAL AND METHODS

Quercetin (10, 25 and 50 mg/kg/b.w.) was given orally to streptozotocin-nicotinamide induced adult male diabetic rats for 28 days. Following treatment completion, rats were sacrificed and sperm were harvested from the cauda epididymis. Sperm count, motility, viability, hyperosmotic swelling (HOS) tail-coiled sperm and morphology were assessed. Levels of lipid peroxidation (LPO) and anti-oxidative enzymes (SOD, CAT and GPx) in sperm with and without H₂O₂ incubation were determined by biochemical assays. Expression levels of SOD, CAT and GPx mRNAs in sperm were evaluated by qPCR. Sperm DNA integrity was estimated by flow cytometry while expression levels of the inflammatory markers NF-κβ and TNF-α in sperm were determined by Western blotting.

RESULTS

In diabetic rats receiving quercetin, sperm count and motility, viability and HOS tail-coiled sperm increased (p < 0.05) while sperm with abnormal morphology decreased. Moreover, sperm SOD, CAT, GPx activities and their mRNA expression levels increased while sperm LPO, NF-κβ and TNF-α levels decreased. In normal and diabetic rat sperm incubated with H₂O₂, a further increase in MDA and further decreases in SOD, CAT and GPx were observed, and these were ameliorated by quercetin treatment.

CONCLUSIONS

In-vivo administration of quercetin to diabetic rats helps to ameliorate sperm damage and improves sperm morphology and functions in DM.

In vivo Assessment of Combined Effects of Glibenclamide and Losartan in Diabetic Rats

OBJECTIVE

Diabetic complications involve multiple pathological pathways, including hyperglycemia-induced oxidative stress and inflammation. Combination therapy is usually employed to improve treatment outcomes and to lower potential adverse effects. In this study, we evaluated the effects of antidiabetic and antihypertensive agents, glibenclamide (GLI) and losartan (LT), on diabetes mellitus (DM)-associated metabolic changes in rats.

MATERIALS AND METHODS

Streptozotocin-induced diabetic animals were orally treated with GLI 5 mg/kg and/or LT 25 mg/kg for 4 weeks. Blood glucose, insulin, aspartate aminotransferase, alanine aminotransferase, urinary creatinine, and urea levels were measured. Serum, liver, and kidney values of inflammatory markers, such as interleukin-1β, tumor necrosis factor alpha, and interleukin-6 were assessed, along with lipid peroxidation products (e.g., thiobarbituric acid reactive substances), endogenous antioxidants (e.g., glutathione), as well as antioxidant enzyme activities (e.g., catalase, superoxide dismutase, and glutathione peroxidase). Finally, histological changes in liver and kidney tissues were evaluated.

RESULTS

DM markedly induced systemic, hepatic, and renal inflammation and lowered antioxidant defense mechanisms. Treatment of diabetic rats with either GLI or LT significantly improved liver and kidney functions and histological structure. Moreover, both medications reduced signs of oxidative stress and inflammation in blood, liver, and kidney samples. Combining GLI and LT showed similar protective potential against systemic, hepatic, and renal oxidative stress and inflammation.

CONCLUSION

Adding LT to GLI therapy revealed prospective antioxidant and anti-inflammatory action, while no synergistic or additive effects were observed.

Mechanistic insights into the augmented effect of bone marrow mesenchymal stem cells and thiazolidinediones in streptozotocin-nicotinamide induced diabetic rats

This study was designed to assess whether the protective effects of bone marrow-derived mesenchymal stem cells (MSCs) against diabetes could be enhanced by pioglitazone (PIO), a PPARγ agonist. Combined MSCs and PIO treatments markedly improved fasting blood glucose, body weight, lipid profile levels, insulin level, insulin resistance, β cell function. Those protective effects also attenuated both pancreatic lesions and fibrosis in diabetic rats and decreased the depletion of pancreatic mediators of glycemic and lipid metabolism including peroxisome proliferator-activated receptor alpha (PPARα), PGC-1α, GLP-1 and IRS-2. Cardiac biogenesis of diabetic groups was also improved with MSCs and/or PIO treatments as reflected by the enhanced up-regulation of the expressions of cardiac IRS1, Glucose transporter 4, PGC-1, PPARα and CPT-1 genes and the down-regulated expression of lipogenic gene SREBP. The combination of MSCs and PIO also potentiated the decrease of abnormal myocardial pathological lesions in diabetic rats. Similarly, the inhibitory effects of MSCs on diabetic cardiac fibrosis and on the up regulations of TGF-β, collagen I and III gene expressions were partial but additive when combined with PIO. Therefore, combined therapy with PIO and BMCs transplantation could further potentiate the protective benefit of MSCs against diabetes and cardiac damage compared to MSCs monotherapy.

Rhinacanthins-rich Extract Enhances Glucose Uptake and Inhibits Adipogenesis in 3T3-L1 Adipocytes and L6 Myotubes

Background:

Obesity is one of the imperative dynamics in the incidence and intensification of type 2 diabetes mellitus (T2DM). Rhinacanthus nasutus leaf extracts are previously reported for their antidiabetic and antiobesity potential.

Objective:

The present study was performed to evaluate glucose uptake stimulatory and antiadipogenic activities of a standardized rhinacanthins-rich extract (RRE) and its marker compounds namely rhinacanthin-C (RC), rhinacanthin-D (RD), and rhinacanthin-N (RN) in 3T3-L1 and L6 cells.

Materials and Methods:

RRE was prepared by a green extraction process, and the marker compounds (RC, RD, and RN) were isolated from the RRE using a silica gel column chromatography. Glucose uptake stimulation in both 3T3-L1 and L6 cells was performed by quantification of residual glucose in the media using glucose oxidase kit. Antiadipogenic activity in 3T3-L1 adipocytes was performed by intracellular lipids quantification using oil red O dye.

Results:

At the highest effective dose, RRE (20 μg/mL) exhibited satisfactory glucose uptake stimulatory effect in 3T3-L1 adipocytes that equivalent to RN (20 μg/mL) and the positive control insulin (0.58 μg/mL) but higher than RC (20 μg/mL) and RD (20 μg/mL). In addition, treatments of L6 myotubes showed that RRE (2.5 μg/mL) exhibited potent and equivalent glucose uptake stimulation (>80%) to RC (2.5 μg/mL) and the standard drugs, insulin (2.90 μg/mL) and metformin (219.5 μg/mL), but higher than RD (2.5 μg/mL) and RN (2.5 μg/mL). Furthermore, RRE (20 μg/mL) exhibited potent antiadipogenic effect in 3T3-L1 adipocytes, which equivalent to RC (20 μg/mL) but higher than RD (20 μg/mL) and RN (20 μg/mL).

Conclusions:

The undertaken study suggests that RRE could be used as an effective remedy in the treatment of obesity-associated T2DM.

SUMMARY

Rhinacanthins-rich extract and its marker compounds showed potent glucose uptake stimulatory activity in 3T3-L1 adipocytes and L6 myotubes

Rhinacanthins-rich extract and rhinacanthin-C showed comparable antiadipogenic effect in 3T3-L1 adipocytes

RRE could be used as an effective remedy in the treatment of obesity-associated T2DM.

Abbreviations used: T2DM: Type-2 diabetes mellitus; RRE: Rhinacanthins-rich extract; RC: Rhinacanthin-C; RD: Rhinacanthin-D; RN: Rhinacanthin-N; α-MEM: α-Minimum essential medium; DMEM: Dulbecco's modified Eagle's medium; HS: Horse serum; FBS: Fetal bovine serum; BSA: Bovine serum albumin; IBMX: 3-isobutyl-1-methylxanthine; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; GO: Glucose oxidase; NMR: Nuclear magnetic resonance; HPLC: High-performance liquid chromatography.

Solid Lipid Nanoparticles of Myricitrin Have Antioxidant and Antidiabetic Effects on Streptozotocin-Nicotinamide-Induced Diabetic Model and Myotube Cell of Male Mouse

Type 2 diabetes mellitus (T2DM) may occur via oxidative stress. Myricitrin is a plant-derived antioxidant, and its solid lipid nanoparticle (SLN) may be more potent. Hence, the present study was conducted to evaluate the effects of myricitrin SLN on streptozotocin-nicotinamide- (STZ-NA-) induced T2DM of the mouse and hyperglycemic myotube. In this experimental study, cold homogenization method was used to prepare SLN. Then, 120 adult male NMRI mice were divided into 7 groups: control, vehicle, diabetes (received STZ 65 mg/kg 15 min after injected NA 120 mg/kg), diabetes + SLN containing myricitrin 1, 3, and 10 mg/kg, and diabetes + metformin. For in vitro study, myoblast (C2C12) cell line was cultured and divided into 6 groups (n = 3): control, hyperglycemia, hyperglycemia + SLN containing myricitrin 1, 3, and, 10 μM, and hyperglycemia + metformin. After the last nanoparticle treatment, plasma samples, pancreas and muscle tissues, and myotubes were taken for experimental assessments. Diabetes increased lipid peroxidation and reduced antioxidant defense along with the hyperglycemia, insulin resistance, and pancreas apoptosis. Hyperglycemia induced oxidative stress, antioxidant impairment, and cellular apoptosis. Myricitrin SLN improved diabetes and hyperglycemia complications in the in vivo and in vitro studies. Therefore, SLN of myricitrin showed antioxidant, antidiabetic, and antiapoptotic effects in the mouse and myotube cells.

Superoxide Scavenging and Antiglycation Activity of Rhinacanthins-rich Extract Obtained from the Leaves of Rhinacanthus nasutus

Background:

Oxidative stress and nonenzymatic protein glycation lead to serious diabetic complications that increase the risk of mortality. Rhinacanthus nasutus leaf crude extracts are previously reported for their antidiabetic, antiglycation, and antioxidant potential.

Objective:

The present study was performed to prepare a standardized rhinacanthins-rich extract (RRE) and evaluate its superoxide scavenging and antiglycation effects as compared to its marker compounds, namely, rhinacanthin-C (RC), rhinacanthin-D (RD), and rhinacanthin-N (RN).

Materials and Methods:

RRE was obtained by microwave-assisted green extraction along with a simple step of fractionation using Amberlite^® column. RC, RD, and RN were isolated from the RRE using silica gel column chromatography. Superoxide scavenging activity was performed by cyclic voltammetry, and fructose-mediated human serum albumin glycation model was used for antiglycation activity. In silico studies were conducted to identify the structure-activity relationships of rhinacanthins.

Results:

On the basis of kinetic measurements, RRE exhibited the most potent antioxidant activity via E_rC_i mechanism, with a 50% inhibitory concentration (IC₅₀) value of 8.0 μg/mL, antioxidant capacity of 39439 M⁻¹, and binding constant of 45709 M⁻¹. Antiglycation assay showed that RRE exhibited almost equivalent glycation inhibitory effect to that of RC, with IC₅₀ values of 39.7 and 37.3 μg/mL, respectively, but higher than that of RD (IC₅₀ of 50.4 μg/mL), RN (IC₅₀ of 89.5 μg/mL), as well as the positive control, rutin (IC₅₀ of 41.5 μg/mL).

Conclusions:

The potent superoxide scavenging and albumin glycation inhibitory effect of RRE rationalized its therapeutic application in various chronic diseases, especially in the complications of diabetes.

SUMMARY

Rhinacanthins-rich extract (RRE) exhibited potent superoxide scavenging activity

RRE and rhinacanthin-C showed remarkable and comparable antiglycation effect

Rhinacanthins exhibited antiglycation activity by masking specific residues of albumin.

Abbreviations used: RRE: Rhinacanthins-rich extract; RC: Rhinacanthin-C; RD: Rhinacanthin-D; RN: Rhinacanthin-N; IC₅₀: 50% inhibitory concentration; Kao: Antioxidant activity coefficient; Kb: Binding constant; E_rC_i: Reversible electron transfer followed by an irreversible chemical reaction; DM: Diabetes mellitus; AGEPs: Advanced glycation end products; NMR: Nuclear magnetic resonance; HPLC: High-performance liquid chromatography; CV: Cyclic voltammetry; DMSO: Dimethyl sulfoxide; Ipa: Anodic peak current; Ipc: Cathodic peak current; HSA: Human serum albumin; MOE: Molecular operating environment; PASSonline: Online prediction of activity spectra for substances.

Rhinacanthin C Alleviates Amyloid-β Fibrils' Toxicity on Neurons and Attenuates Neuroinflammation Triggered by LPS, Amyloid-β, and Interferon-γ in Glial Cells

Neuroinflammation plays a central role in the pathophysiology of Alzheimer's disease (AD). Compounds that suppress neuroinflammation have been identified as potential therapeutic targets for AD. Rhinacanthin C (RC), a naphthoquinone ester found in Rhinacanthus nasutus Kurz (Acanthaceae), is currently proposed as an effective molecule against inflammation. However, the exact role of RC on neuroinflammation remains to be elucidated. In the present study, we investigated RC effect on modulating lipopolysaccharides (LPS), amyloid-β peptide (Aβ), or interferon-γ- (IFN-γ-) evoked pathological events in neurons and glia. Our findings demonstrated that RC prevented Aβ-induced toxicity in rat hippocampal neurons and attenuated LPS-activated nitric oxide (NO) production, inducible nitric oxide synthase (iNOS) expression, and NF-κB signaling in rat glia. Likewise, RC suppressed LPS-induced neuroinflammation by reducing NO production and iNOS, IL-1β, CCL-2, and CCL-5 mRNA levels in rat microglia. Further studies using BV-2 microglia revealed that RC inhibited LPS-, Aβ-, and IFN-γ-stimulated IL-6 and TNF-α secretion. Of note, NF-κB and ERK activation was abrogated by RC in BV-2 cell response to Aβ or IFN-γ. Moreover, RC protected neurons from Aβ-stimulated microglial conditioned media-dependent toxicity. Collectively, these data highlight the beneficial effects of RC on neuroprotection and support the therapeutic implications of RC to neuroinflammation-mediated conditions.

Anti-Inflammatory, Antiapoptotic and Proproliferative Effects of Vitis vinifera Seed Ethanolic Extract in the Liver of Streptozotocin-Nicotinamide-Induced Type 2 Diabetes in Male Rats

OBJECTIVES

Consumption of Vitis vinifera seed has been reported to ameliorate liver pathology in diabetes mellitus; however, the mechanisms underlying its effects remain unknown. In this study, the anti-inflammatory, anti-apoptotic and pro-proliferative effects of the ethanolic seed extract of V. vinifera (VVSEE) in the liver in cases of diabetes were identified.

METHODS

Adult male rats with streptozotocin-nicotinamide-induced diabetes were given 50, 100 or 200 mg/kg body weight VVSEE orally for 28 days. At the end of the treatment, body weights were determined, and the blood was collected for analyses of fasting blood glucose, insulin and liver enzyme levels. Following sacrifice, livers were harvested and their wet weights and glycogen contents were measured. Histologic appearances of the livers were observed under light microscopy, and the expression and distribution of inflammatory, apoptosis and proliferative markers in the livers were identified by molecular biologic techniques.

RESULTS

Treatment of rats with diabetes by VVSEE attenuates decreased body weight, liver weight and liver glycogen content. Additionally, increases in fasting blood glucose levels and liver enzyme levels and decreases in serum insulin levels were ameliorated. Lesser histopathologic changes were also observed: decreased inflammation and apoptosis, as indicated by decreased levels of inflammatory markers (TNF-α, NF-Kβ, IKK-β, IL-6, IL-1β) and apoptosis markers (caspase-3, caspase-9 and Bax). VVSEE treatment induces increase in hepatocyte regeneration, as indicated by increased PCNA and Ki-67 distribution in the livers of rats with diabetes. Several molecules identified in VVSEE via gas chromatography mass spectrometry might contribute to these effects.

CONCLUSIONS

The anti-inflammatory, anti-apoptotic and pro-proliferative effects of VVSEE could account for its hepatoprotective actions in diabetes.

Phyllanthus niruri leaves aqueous extract improves kidney functions, ameliorates kidney oxidative stress, inflammation, fibrosis and apoptosis and enhances kidney cell proliferation in adult male rats with diabetes mellitus

ETHNOPHARMACOLOGICAL RELEVANCE

Phylanthus niruri has been used to treat ailments related to the urogenital organs. In this study, this herb was hypothesized to help to ameliorate kidney disease in diabetes mellitus (DM).

AIMS

To investigate P. niruri leaves aqueous extract (PN) effects on kidney functions, histopathological changes and levels of oxidative stress, inflammation, fibrosis, apoptosis and proliferation in DM.

METHODS

PN was orally administered to streptozotocin-nicotinamide-induced male diabetic rats for 28 days. At the end of the treatment, fasting blood glucose (FBG) and kidney functions were measured. Kidney somatic index, histopathological changes and levels of RAGE, Nrf2, oxidative stress markers (TBARS, SOD, CAT and GPx), inflammatory markers (NFkβ-p65, Ikk-β, TNF-α, IL-1β and IL-6), apoptosis markers (caspase-3, caspase-9 and Bax), fibrosis markers (TGF-β1, VEGF and FGF-1) and proliferative markers (PCNA and Ki-67) were determined by biochemical assays, qPCR, Western blotting, immunohistochemistry or immunofluorescence.

RESULTS

Administration of PN helps to maintain near normal FBG, creatinine clearance (CCr), blood urea nitrogen (BUN), BUN/Cr ratio, serum electrolytes, uric acid and urine protein levels in DM. Decreased RAGE, TBARS and increased Nrf2, SOD-1, CAT and GPx-1 were observed in PN-treated diabetic rat kidneys. Expression of inflammatory, fibrosis and apoptosis markers in the kidney reduced but expression of proliferative markers increased following PN treatment. Lesser histopathological changes were observed in the kidney of PN-treated diabetic rats.

CONCLUSION

PN helps to preserve near normal kidney function and prevents histopathological changes via ameliorating oxidative stress, inflammation, fibrosis and apoptosis while enhancing proliferation of the kidney in DM.

Methanolic seed extract of Vitis vinifera ameliorates oxidative stress, inflammation and ATPase dysfunction in infarcted and non-infarcted heart of streptozotocin-nicotinamide induced male diabetic rats

BACKGROUND

We hypothesized that consumption of Vitis vinifera seed by diabetics could help to ameliorate myocardial damage. Therefore, in this study, we investigated effects of V. vinifera seed methanolic extract (VVSME) on parameters related to myocardial damage in diabetes with or without myocardial infarction (MI).

METHODS

Streptozotocin-nicotinamide induced diabetic rats received oral VVSME for 28days. MI was induced by intraperitoneal injection of isoproterenol on last two days. Prior to sacrifice, blood was collected and fasting blood glucose (FBG), glycated hemoglobin (HbA1c), lipid profile and insulin levels were measured. Levels of serum cardiac injury marker (troponin-I and CK-MB) were determined and histopathological changes in the heart were observed following harvesting. Levels of oxidative stress (LPO, SOD, CAT, GPx and RAGE), inflammation (NF-κB, TNF-α, IL-1β and IL-6) and cardiac ATPases (Na(+)/K(+)-ATPase and Ca(2+)-ATPase) were determined in heart homogenates. LC-MS was used to identify constituents in the extracts.

RESULTS

Consumption of VVSME by diabetic rats with or without MI improved the metabolic profiles while decreased the cardiac injury marker levels with lesser myocardial damage observed. Additionally, VVSME consumption reduced the levels of LPO, RAGE, TNF-α, Iκκβ, NF-κβ, IL-1β and IL-6 while increased the levels of SOD, CAT, GPx, Na(+)/K(+)-ATPase and Ca(2+)-ATPase in the infarcted and non-infarcted heart of diabetic rats (p<0.05). LC-MS analysis revealed 17 major compounds in VVSME which might be responsible for the observed effects.

CONCLUSIONS

Consumption of VVSME by diabetics helps to ameliorate damage to the infarcted and non-infarcted myocardium by decreasing oxidative stress, inflammation and cardiac ATPases dysfunctions.