Antihyperglycemic effects of baicalin on streptozotocin - nicotinamide induced diabetic rats

Baicalin ameliorates insulin resistance and regulates hepatic glucose metabolism via activating insulin signaling pathway in obese pre-diabetic mice

BACKGROUND

Diabetes belongs to the most prevalent metabolic diseases worldwide, which is featured with insulin resistance, closely associated with obesity and urgently needs to be treated. Baicalin, belonging to natural flavonoids, has been reported to inhibit oxidative stress or inflammatoin.

PURPOSE

This study investigated the properties of baicalin on modulating abnormal glucolipid metabolism, as well as the underlying in-vitro and in-vivo mechanisms.

METHODS

Insulin-resistant (IR)-HepG2 cells were stimulated by dexamethasone (20 µM) and high glucose (50 mM) for 48 h and incubated with or without baicalin or metformin for another 16 h. Male C57BL/6 J mice were fed with a high-fat diet (HFD, 60 % kcal% fat) during the total 14 weeks. Obese mice were then administered with baicalin (50 and 100 mg/kg) or vehicle solution everyday through oral gavage during the last 4-week period. Moreover, baicalin metabolisms in vitro and in vivo were determined using UPLC/MS/MS to study its metabolism situation.

RESULTS

Exposure to dexamethasone and high glucose damaged the abilities of glycogen synthesis and glucose uptake with elevated oxidative stress and increased generation levels of advanced glycation end-products (AGEs) in HepG2 cells. These impairments were basically reversed by baicalin treatment. Four-week oral administration with baicalin ameliorated hyperglycemia and dyslipidemia in HFD-induced obese and pre-diabetic mice. Downregulation of IRS/PI3K/Akt signaling pathway accomplished with reduced GLUT4 expression and enhanced GSK-3β activity was observed in insulin resistant HepG2 cells as well as liver tissues from pre-diabetic mice; and such effect was prevented by baicalin. Moreover, baicalin and its matabolites were detected in IR-HepG2 cells and mouse plasma.

CONCLUSION

The study illustrated that baicalin alleviated insulin resistance by activating insulin signaling pathways and inhibiting oxidative stress and AGEs production, revealing the potential of baicalin to be a therapeutic natural flavonoid against hepatic insulin and glucose-lipid metabolic disturbance in pre-diabetes accompanied with obesity.

Therapeutic strategy of biological macromolecules based natural bioactive compounds of diabetes mellitus and future perspectives: A systematic review

High blood glucose levels are a hallmark of the metabolic syndrome known as diabetes mellitus. More than 600 million people will have diabetes by 2045 as the global prevalence of the disease continues to rise. Contemporary antidiabetic drugs reduce hyperglycemia and its consequences. However, these drugs come with undesirable side effects, so it's encouraging that research into plant extracts and bioactive substances with antidiabetic characteristics is on the rise. Natural remedies are preferable to conventional anti-diabetic drugs since they are safer for the body, more affordable and have fewer potential adverse effects. Biological macromolecules such as liposomes, niosomes, polymeric nanoparticles, solid lipid nanoparticles, nanoemulsions and metallic nanoparticles are explored in this review. Current drug restrictions have been addressed, and the effectiveness of plant-based antidiabetic therapies has enhanced the merits of these methods. Plant extracts' loading capacity and the carriers' stability are the primary obstacles in developing plant-based nanocarriers. Hydrophilic, hydrophobic, and amphiphilic drugs are covered, and a brief overview of the amphipathic features of liposomes, phospholipids, and lipid nanocarriers is provided. Metallic nanoparticles' benefits and attendant risks are highlighted to emphasize their efficiency in treating hyperglycemia. Researchers interested in the potential of nanoparticles loaded with plant extracts as antidiabetic therapeutics may find the current helpful review.

The Anti-Diabetic Potential of Baicalin: Evidence from Rodent Studies

Baicalin is a biologically active flavonoid compound that benefits the organism in various pathological conditions. Rodent studies have shown that this compound effectively alleviates diabetes-related disturbances in models of type 1 and type 2 diabetes. Baicalin supplementation limited hyperglycemia and improved insulin sensitivity. The anti-diabetic effects of baicalin covered the main insulin-sensitive tissues, i.e., the skeletal muscle, the adipose tissue, and the liver. In the muscle tissue, baicalin limited lipid accumulation and improved glucose transport. Baicalin therapy was associated with diminished adipose tissue content and increased mitochondrial biogenesis. Hepatic lipid accumulation and glucose output were also decreased as a result of baicalin supplementation. The molecular mechanism of the anti-diabetic action of this compound is pleiotropic and is associated with changes in the expression/action of pivotal enzymes and signaling molecules. Baicalin positively affected, among others, the tissue insulin receptor, glucose transporter, AMP-activated protein kinase, protein kinase B, carnitine palmitoyltransferase, acetyl-CoA carboxylase, and fatty acid synthase. Moreover, this compound ameliorated diabetes-related oxidative and inflammatory stress and reduced epigenetic modifications. Importantly, baicalin supplementation at the effective doses did not induce any side effects. Results of rodent studies imply that baicalin may be tested as an anti-diabetic agent in humans.

The role of mosapride and levosulpiride in gut function and glycemic control in diabetic rats

BACKGROUND AND STUDY AIMS

Gastroparesis is a well-known consequence of long-standing diabetes that presents with gastric dysmotility in the absence of gastric outlet obstruction. This study aimed to evaluate the therapeutic effects of mosapride and levosulpiride on improving gastric emptying in type 2 diabetes mellitus (T2DM) while regulating glycemic levels.

MATERIAL AND METHODS

Rats were divided into the normal control, untreated diabetic, metformin-treated (100 mg/kg/day), mosapride-treated (3 mg/kg/day), levosulpiride-treated (5 mg/kg/day), metformin (100 mg/kg/day) + mosapride (3 mg/kg/day)-treated, and metformin (100 mg/kg/day) + levosulpiride (5 mg/kg/day)-treated diabetic groups. T2DM was induced by a streptozotocin-nicotinamide model. Fourweeks from diabetes onset, the treatment was started orally daily for 2 weeks. Serum glucose, insulin, and glucagon-like peptide 1 (GLP-1) levels were measured. Gastric motility study was performed using isolated rat fundus and pylorus strip preparations. Moreover, the intestinal transit rate was measured.

RESULTS

Mosapride and levosulpiride administration showed a significant decrease in serum glucose levels with improvement of gastric motility and intestinal transit rate. Mosapride showed a significant increase in serum insulin and GLP-1 levels. Metformin with mosapride and levosulpiride co-administration showed better glycemic control and gastric emptying than either drug administered alone.

CONCLUSION

Mosapride and levosulpiride showed comparable prokinetic effects. Metformin administration with mosapride and levosulpiride showed better glycemic control and prokinetic effects. Mosapride provided better glycemic control than levosulpiride. Metformin + mosapride combination provided superior glycemic control and prokinetic effects.

Flavonoids' Dual Benefits in Gastrointestinal Cancer and Diabetes: A Potential Treatment on the Horizon?

Diabetes and gastrointestinal cancers (GI) are global health conditions with a massive burden on patients' lives worldwide. The development of both conditions is influenced by several factors, such as diet, genetics, environment, and infection, which shows a potential link between them. Flavonoids are naturally occurring phenolic compounds present in fruits and vegetables. Once ingested, unabsorbed flavonoids reaching the colon undergo enzymatic modification by the gut microbiome to facilitate absorption and produce ring fission products. The metabolized flavonoids exert antidiabetic and anti-GI cancer properties, targeting major impaired pathways such as apoptosis and cellular proliferation in both conditions, suggesting the potentially dual effects of flavonoids on diabetes and GI cancers. This review summarizes the current knowledge on the impact of flavonoids on diabetes and GI cancers in four significant pathways. It also addresses the synergistic effects of selected flavonoids on both conditions. While this is an intriguing approach, more studies are required to better understand the mechanism of how flavonoids can influence the same impaired pathways with different outcomes depending on the disease.

A Review on the Delivery of Plant-Based Antidiabetic Agents Using Nanocarriers: Current Status and Their Role in Combatting Hyperglycaemia

Diabetes mellitus is a prevalent metabolic syndrome that is associated with high blood glucose levels. The number of diabetic patients is increasing every year and the total number of cases is expected to reach more than 600 million worldwide by 2045. Modern antidiabetic drugs alleviate hyperglycaemia and complications that are caused by high blood glucose levels. However, due to the side effects of these drugs, plant extracts and bioactive compounds with antidiabetic properties have been gaining attention as alternative treatments for diabetes. Natural products are biocompatible, cheaper and expected to cause fewer side effects than the current antidiabetic drugs. In this review, various nanocarrier systems are discussed, such as liposomes, niosomes, polymeric nanoparticles, nanoemulsions, solid lipid nanoparticles and metallic nanoparticles. These systems have been applied to overcome the limitations of the current drugs and simultaneously improve the efficacy of plant-based antidiabetic drugs. The main challenges in the formulation of plant-based nanocarriers are the loading capacity of the plant extracts and the stability of the carriers. A brief review of lipid nanocarriers and the amphipathic properties of phospholipids and liposomes that encapsulate hydrophilic, hydrophobic and amphiphilic drugs is also described. A special emphasis is placed on metallic nanoparticles, with their advantages and associated complications being reported to highlight their effectiveness for treating hyperglycaemia. The present review could be an interesting paper for researchers who are working in the field of using plant extract-loaded nanoparticles as antidiabetic therapies.

Assessment of Antioxidative and Alpha-Amylase Potential of Polyherbal Extract

The present study aims to prepare a polyherbal formulation (PHF) of Azadirachta indica (Neem), Aloe barbadensis (Aloe vera), Allium sativum (garlic), Acacia arabica (Babul), and Aegle marmelos (Bel) and evaluation of antidiabetic and antioxidant activity utilizing the in vitro model. Air-dried powder of 5 medicinal plants, which are divided into equal portions, and PHF, is prepared by the soxhlet technique using polar and nonpolar solvents. The PHF is screened for the phytochemical screening, and then the antidiabetic activity is determined by alpha-amylase inhibition. The extracts thus obtained are also subjected to the inhibition assay by the use of (DNS) dinitro salicylic acid. The antioxidant activity was determined by the DPPH radical scavenging assay, H₂O₂ scavenging assay, and TBARS assay. In in vitro study, the result revealed polyherbal formulation in which hot water extract has the topmost inhibitory effect on alpha-amylase activity, ranging from 20.4% to 79.5% with an IC50 value of 48.98 ± 0.31 μg/ml. This extract clearly showed the effective lowering of postprandial hypertriglyceridemia (PPHG). In the antioxidant activity carried out by using the (DPPH) radical scavenging assay, the highest result was obtained by the concentration of 250 μg/ml, which was around 77.2 ± 0.05 with statistical significance compared with control (a: p < 0.01; b: p < 0.001), while in the GTA method, the highest result was obtained by the concentration of 250 μg/ml, which was around 78.2 ± 0.05, and in the case of the TBARS assay, the concentration of 250 μg/ml gave around 76.2 ± 0.03 anti-oxidant value. In conclusion, the study shows that polyherbal formulation has superior antidiabetic activity and antioxidant properties.

Scutellaria baicalensis and its constituents baicalin and baicalein as antidotes or protective agents against chemical toxicities: a comprehensive review

Scutellaria baicalensis (SB), also known as the Chinese skullcap, has a long history of being used in Chinese medicine to treat a variety of conditions ranging from microbial infections to metabolic syndrome and malignancies. Numerous studies have reported that treatment with total SB extract or two main flavonoids found in its root and leaves, baicalin (BA) and baicalein (BE), can prevent or alleviate the detrimental toxic effects of exposure to various chemical compounds. It has been shown that BA and BE are generally behind the protective effects of SB against toxicants. This paper aimed to review the protective and therapeutic effects of SB and its main components BA and BE against chemical compounds that can cause intoxication after acute or chronic exposure and seriously affect different vital organs including the brain, heart, liver, and kidneys. In this review paper, we had a look into a total of 221 in vitro and in vivo studies from 1995 to 2021 from the scientific databases PubMed, Scopus, and Web of Science which reported protective or therapeutic effects of BA, BE, or SB against drugs and chemicals that one might be exposed to on a professional or accidental basis and compounds that are primarily used to simulate disease models. In conclusion, the protective effects of SB and its flavonoids can be mainly attributed to increase in antioxidants enzymes, inhibition of lipid peroxidation, reduction of inflammatory cytokines, and suppression of apoptosis pathway.

Baicalin protects against insulin resistance and metabolic dysfunction through activation of GALR2/GLUT4 signaling

BACKGROUND

Type 2 diabetes mellitus is a complex metabolic disorder associated with obesity, glucose intolerance and insulin resistance. Activation of GALR2 has been proposed as a therapeutic target for the treatment of insulin resistance. The previous studies showed that baicalin could mitigate insulin resistance, but the detailed mechanism of baicalin on insulin resistance has not been fully explored yet.

PURPOSE

In the present study, we evaluated whether baicalin mitigated insulin resistance via activation of GALR2 signaling pathway.

STUDY DESIGN/METHODS

Baicalin (25 mg/kg/d and 50 mg/kg/d) and/or GALR2 antagonist M871 (10 mg/kg/d) were injected individually or in combinations into obese mice once a day for three weeks, and normal and GALR2 knockdown myotubes were treated with baicalin (100 μM and 400 μM) or metformin (4 mM) in the absence or presence of M871 (800 nM) for 12 h, respectively. The molecular mechanism was explored in skeletal muscle and L6 myotubes.

RESULTS

The present findings showed that baicalin mitigated hyperglycemia and insulin resistance and elevated the levels of PGC-1α, GLUT4, p-p38MAPK, p-AKT and p-AS160 in skeletal muscle of obese mice. Strikingly, the baicalin-induced beneficial effects were abolished by GALR2 antagonist M871 in obese mice. In vitro, baicalin dramatically augmented glucose consumption and the activity of PGC1α-GLUT4 axis in myotubes through activation of p38MAPK and AKT pathways. Moreover, baicalin-induced elevations in glucose consumption related genes were abolished by GALR2 antagonist M871 or silencing of GALR2 in myotubes.

CONCLUSIONS

The present study for the first time demonstrated that baicalin protected against insulin resistance and metabolic dysfunction mainly through activation of GALR2-GLUT4 signal pathway. Our findings identified that activation of GALR2-GLUT4 signal pathway by baicalin could be a new therapeutic approach to treat insulin resistance and T2DM in clinic.

Luteolin Improves Perivascular Adipose Tissue Profile and Vascular Dysfunction in Goto-Kakizaki Rats

We investigated the effects of luteolin on metabolism, vascular reactivity, and perivascular adipose tissue (PVAT) in nonobese type 2 diabetes mellitus animal model, Goto-Kakizaki (GK) rats. Methods: Wistar and GK rats were divided in two groups: (1) control groups treated with vehicle; (2) groups treated with luteolin (10 mg/kg/day, for 2 months). Several metabolic parameters such as adiposity index, lipid profile, fasting glucose levels, glucose and insulin tolerance tests were determined. Endothelial function and contraction studies were performed in aortas with (PVAT+) or without (PVAT−) periaortic adipose tissue. We also studied vascular oxidative stress, glycation and assessed CRP, CCL2, and nitrotyrosine levels in PVAT. Results: Endothelial function was impaired in diabetic GK rats (47% (GK − PVAT) and 65% (GK + PVAT) inhibition of maximal endothelial dependent relaxation) and significantly improved by luteolin treatment (29% (GK − PVAT) and 22% (GK + PVAT) inhibition of maximal endothelial dependent relaxation, p < 0.01). Vascular oxidative stress and advanced glycation end-products’ levels were increased in aortic rings (~2-fold, p < 0.05) of diabetic rats and significantly improved by luteolin treatment (to levels not significantly different from controls). Periaortic adipose tissue anti-contractile action was significantly rescued with luteolin administration (p < 0.001). In addition, luteolin treatment significantly recovered proinflammatory and pro-oxidant PVAT phenotype, and improved systemic and metabolic parameters in GK rats. Conclusions: Luteolin ameliorates endothelial dysfunction in type 2 diabetes and exhibits therapeutic potential for the treatment of vascular complications associated with type 2 diabetes.

Anti-diuretic and anti-glycemic properties of Jatropha gossypiifolia L. leave extract on wistar rats

Background

Jatropha gossypiifolia L. is a widespread plant in tropical and sub-tropical countries used in traditional medicine. This study investigated the anti-diuretic and anti-hyperglycemia activities of J. gossypiifolia leave extract on streptozotocin-induced diabetic rats.

Methods

The leaves was shade dried, pulverized and prepared into extract. 30, 50 and 100 mg/kg of the leaves extracts of J. gossypiifolia was subject to diuretics and hyperglycemic properties using established protocol of diuretic and diabetes test on the rat bladders emptied via mild compression in the pelvic region and gently pulling of their tails. 0.5 ml/kg normal saline, reference drug and the tested were administered with a single dose of the various drugs, and Streptozotocin (STZ) was freshly prepared in 0.1 M citrate buffer with pH 4.5 prior to induction, animals were fasted 24 h and single dose of 45 mg STZ per kg body weight was administered intraperitoneally. Urine and blood samples were isolated from rats and centrifuged for the determination of renal function test. Diuretic and antidiabetic indexes where evaluated using adopted method.

Results

This study showed that, graded doses of the extract significantly increased diuretic effect, specifically at 100 mg/kg increased diuretic index at 4.29 and urine volume 5.06 and 10 mg/kg Hydrochlorothiazide with 6.23 ml when compared untreated group (1.18 ml) (p < 0.0001). Also, it regulated renal function in homeostatic state. Graded doses at (30, 50 and 100 mg/kg) of the extract significantly reduced streptozotocine induced increased blood glucose level at day 14 (84.00, 60.67 and 42.00 IU/mL) when compared with 20 mg/kg glibenclamide and diabetics control (81.67 and 463.00 IU/mL) (p > 0.05). Also, the extract maintained a normal body mass indexes, biochemical and anatomical structure.

Conclusion

The effect associated with J. gossypiifolia potentiated its anti-diuretic and anti-hyperglycemic properties as early stated in the ethnomedicinal reports.

Design, synthesis, kinetic, molecular dynamics, and hypoglycemic effect characterization of new and potential selective benzimidazole derivatives as Protein Tyrosine Phosphatase 1B inhibitors

Protein-tyrosine phosphatase 1B (PTP1B) is a negative regulator of insulin signaling pathway and has been validated as a therapeutic target for type 2 diabetes. A wide variety of scaffolds have been included in the structure of PTP1B inhibitors, one of them is the benzimidazole nucleus. Here, we report the design and synthesis of a new series of di- and tri- substituted benzimidazole derivatives including their kinetic and structural characterization as PTP1B inhibitors and hypoglycemic activity. Results show that compounds 43, 44, 45, and 46 are complete mixed type inhibitors with a Ki of 12.6 μM for the most potent (46). SAR type analysis indicates that a chloro substituent at position 6(5), a β-naphthyloxy at position 5(6), and a p-benzoic acid attached to the linker 2-thioacetamido at position 2 of the benzimidazole nucleus, was the best combination for PTP1B inhibition and hypoglycemic activity. In addition, molecular dynamics studies suggest that these compounds could be potential selective inhibitors from other PTPs such as its closest homologous TCPTP, SHP-1, SHP-2 and CDC25B. Therefore, the compounds reported here are good hits that provide structural, kinetic, and biological information that can be used to develop novel and selective PTP1B inhibitors based on benzimidazole scaffold.

Baicalin Alleviates Oxidative Stress and Inflammation in Diabetic Nephropathy via Nrf2 and MAPK Signaling Pathway

Background

Oxidative stress and inflammation play essential roles in the development and progression of diabetic nephropathy (DN). Baicalin (BAI), a natural flavonoid, has been showed to have a renoprotective effect in various renal diseases. However, its underlying mechanisms in DN remain unclear. In this study, we explored the potential effects and underlying mechanisms of BAI on DN using a spontaneous DN model.

Methods

The protective effects of BAI on DN have been evaluated by detecting DN-related biochemical indicators, kidney histopathology and cell apoptosis. After that, we examined the level of renal oxidative stress and inflammation to explain BAI’s renoprotective effects. Then, Nrf2 pathway was tested to clarify its antioxidant activity, and kidney transcriptomics was conducted to elucidate its anti-inflammatory activity. Finally, Western blot was applied for final mechanism verification.

Results

Our results found that BAI effectively ameliorated diabetic conditions, proteinuria, renal histopathological changes and cell apoptosis in DN. BAI significantly improved the kidney levels of glutathione peroxidase (GSH-PX), superoxide dismutase (SOD) and catalase (CAT), and reduced malondialdehyde (MDA) level. Meanwhile, the infiltration of inflammatory cells including T-lymphocytes, T-helper cells, neutrophils and macrophages, and the mRNA levels of pro-inflammatory cytokines (IL-1β, IL-6, MCP-1 and TNFα) were also obviously inhibited by BAI. Afterward, Western blot found that BAI significantly activated Nrf2 signaling and increased the expression of downstream antioxidant enzymes (HO-1, NQO-1). Kidney transcriptomics revealed that the inhibition of MAPK signaling pathway may contribute to BAI’s anti-inflammatory activity, which has also been verified in later experiment. BAI treatment did obviously inhibit the activation of canonical pro-inflammatory signaling pathway MAPK family, such as Erk1/2, JNK and P38.

Conclusion

In summary, our data demonstrated that BAI can treat DN by alleviating oxidative stress and inflammation, and its underlying mechanisms were associated with the activation of Nrf2-mediated antioxidant signaling pathway and the inhibition of MAPK-mediated inflammatory signaling pathway.

The Immunomodulating Effect of Baicalin on Inflammation and Insulin Resistance in High-Fat-Diet-Induced Obese Mice

Background

Obesity is a chronic low-grade systemic inflammation state, which causes insulin resistance, diabetes, and other metabolic diseases. Baicalin is known to have anti-inflammatory and antiobesity effects. In this study, we investigated the cellular and molecular immunological effects of baicalin on obesity-induced inflammation.

Methods

Male C57BL/6 mice were assigned to four groups: the normal chow, high-fat diet (HFD), BC2 (HFD + baicalin 200 mg/kg), and BC4 (HFD + baicalin 400 mg/kg) group; the three groups except normal chow were fed with a high-fat diet for 8 weeks to induce obesity followed by baicalin treatment with two doses for 8 weeks. The body weight, epididymal fat weight, liver weight, food intake, oral glucose tolerance test (OGTT), oral fat tolerance test (OFTT), and serum lipids were measured. We evaluated insulin resistance by measuring the serum insulin level and homeostatic model assessment of insulin resistance (HOMA-IR). Also, the major obesity-associated immune cells including monocytes, macrophages, T lymphocytes, and dendritic cells in the blood, fat, and liver and the inflammatory and insulin signaling-related gene expressions in the fat and liver were evaluated.

Results

Baicalin significantly reduced the body weight and liver weight and improved serum fasting glucose, insulin, HOMA-IR, free fatty acid, HDL cholesterol, and the levels of glucose and triglyceride at each time point in the OGTT and OFTT. In the analysis of immune cells, baicalin significantly decreased inflammatory Ly6C^hi monocytes, M1 adipose tissue macrophages (ATMs), and M1 Kupffer cells. On the contrary, baicalin increased anti-inflammatory M2 ATMs and liver CD4+ T cells and CD4/CD8 ratio. In the analysis of inflammatory and insulin signaling molecules, baicalin significantly downregulated the gene expression of tumor necrosis factor-α, F4/80, and C-C motif chemokine 2 while upregulated the insulin receptor mRNA expression.

Conclusion

From these results, baicalin can be a promising treatment option for obesity and its related metabolic diseases based on its anti-inflammatory property.

Baicalin Improves Cardiac Outcome and Survival by Suppressing Drp1-Mediated Mitochondrial Fission after Cardiac Arrest-Induced Myocardial Damage

Myocardial injury after cardiac arrest (CA) often results in severe myocardial dysfunction and death involving mitochondrial dysfunction. Here, we sought to investigate whether baicalin, a natural flavonoid compound, exerts cardioprotection against CA-induced injury via regulating mitochondrial dysfunction. We subjected the rats to asphyxia CA after a daily baicalin treatment for 4 weeks. After the return of spontaneous circulation, baicalin treatment significantly improved cardiac function performance, elevated survival rate from 35% to 75%, prevented necrosis and apoptosis in the myocardium, which was accompanied by reduced phosphorylation of Drp1 at serine 616, inhibited Drp1 translocation to the mitochondria and mitochondrial fission, and improved mitochondrial function. In H9c2 cells subjected to simulated ischemia/reperfusion, increased phosphorylation of Drp1 at serine 616 and subsequently enhanced mitochondrial Drp1 translocation as well as mitochondrial fission, augmented cardiomyocyte death, increased reactive oxygen species production, released cytochrome c from mitochondria and injured mitochondrial respiration were efficiently improved by baicalin and Drp1 specific inhibitor with Mdivi-1. Furthermore, overexpression of Drp1 augmented excessive mitochondrial fission and abolished baicalin-afforded cardioprotection, indicating that the protective impacts of baicalin are linked to the inhibition of Drp1. Altogether, our findings disclose for the first time that baicalin offers cardioprotection against ischemic myocardial injury after CA by inhibiting Drp1-mediated mitochondrial fission. Baicalin might be a prospective therapy for the treatment of post-CA myocardial injury.

Baicalin and its aglycone: a novel approach for treatment of metabolic disorders

BACKGROUND

The current strategies for prevention and treatment of insulin resistance and type 2 diabetes are not fully effective and frequently accompanied by many negative effects. Therefore, novel ways to prevent insulin resistance and type 2 diabetes are urgently needed. The roots of Scutellaria radix are commonly used in traditional Chinese medicines for prevention and treatment of type 2 diabetes, atherosclerosis, hypertension, hyperlipidemia, dysentery, and other respiratory disorders. Baicalin and baicalein are the major and active ingredient extracts from Scutellaria baicalensis.

METHODS

A comprehensive and systematic review of literature on baicalin and baicalein was carried out.

RESULTS

Emerging evidence indicated that baicalin and baicalein possessed hepatoprotective, anti-oxidative, anti-dyslipidemic, anti-lipogenic, anti-obese, anti-inflammatory, and anti-diabetic effects, being effective for treating obesity, insulin resistance, non-alcoholic fatty liver, and dyslipidemia. Besides, baicalin and baicalein are almost non-toxic to epithelial, peripheral, and myeloid cells.

CONCLUSION

The purpose of this study is to focus on the therapeutic applications and accompanying molecular mechanisms of baicalin and baicalein against hyperglycemia, insulin resistance, type 2 diabetes, hyperlipidemia, obesity, and non-alcoholic fatty liver, and trying to establish a novel anti-obese and anti-diabetic strategy.

Antidiabetic and Hypolipidemic Effects of 5,7-Dimethoxyflavone in Streptozotocin-Induced Diabetic Rats

BACKGROUND The flavones are considered as competent antidiabetic molecules due to their strong antioxidant activities and higher in vivo stability. The present study evaluated the antidiabetic and hypolipidemic effects of 5,7-dimethoxyflavone in streptozotocin (STZ)-induced diabetic rat models. MATERIAL AND METHODS The antidiabetic potential of 5,7-dimethoxyflavone was evaluated in streptozotocin-induced diabetic rats. The serum levels of triglyceride, total cholesterol, and high-density lipoprotein cholesterol were measured using the Randox assay kit. Histopathological examination was carried out by hematoxylin and eosin (HE) staining. RESULTS Oral administration of 5,7-dimethoxyflavone significantly reduced STZ-induced enhancement in blood sugar and glycosylated hemoglobin, as well as significant increases in C-peptide, insulin, hemoglobin, and total protein content (p<0.05). Additionally, treatment with 5,7-dimethoxyflavone resulted in a remarkable increase in non-enzymic antioxidants. Administration of 5,7-dimethoxyflavone had a hypolipidemic effect by significantly reducing levels of serum triglycerides, total cholesterol, and low-density lipoproteins. The histopathological examination of rat pancreases revealed the beneficial effect of 5,7-dimethoxyflavone and protection of ß cell integrity in STZ-induced diabetic rats. CONCLUSIONS These findings reflect the antidiabetic and hypolipidemic effects of 5,7-dimethoxyflavone, suggesting that 5,7-dimethoxyflavone may be a promising compound for use in development of new antidiabetic drugs.

Baicalin ameliorates hepatic insulin resistance and gluconeogenic activity through inhibition of p38 MAPK/PGC-1α pathway

BACKGROUND

Although the results of our and other studies show that baicalin can enhance glucose uptake and insulin sensitivity in skeletal muscle and adipocytes of mice, the specific metabolic contribution of baicalin on hepatic insulin resistance and gluconeogenic activity is still unclear.

PURPOSE

The aim of this study is to investigate whether baicalin is involved in regulation of hepatic insulin resistance and gluconeogenic activity and its underlying mechanisms.

STUDY DESIGN/METHODS

In the present study, high-fat diet-induced obese mice were given 50 mg/kg baicalin intraperitoneally (i.p.) once a day for 21 consecutive days, and hepatocytes were treated with baicalin (100 μM) or metformin (100 μM) in the presence of glucagon (200 nM) for 12 h. Then insulin resistance indexes and genes related to gluconeogenesis were examined in liver tissues.

RESULTS

The present findings showed that baicalin decreased body weight, HOMA-IR, and alleviated high fat diet-induced glucose intolerance, hyperglycemia and insulin resistance in diet-induced obese mice. Furthermore, baicalin markedly suppressed p-p38 MAPK, p-CREB, FoxO1, PGC-1α, PEPCK and G6Pase expression in liver of obese mice and hepatocytes. Moreover, inhibition of gluconeogenic genes by baicalin was also strengthened by p38MAPK inhibitor in hepatocytes.

CONCLUSION

Baicalin suppressed expression of PGC-1α and gluconeogenic genes, and reduced glucose production in high-fat diet-induced obese mice. Baicalin ameliorated hepatic insulin resistance and gluconeogenic activity mainly through inhibition of p38 MAPK/PGC-1α signal pathway. This study provides a possibility of using baicalin to treat hyperglycemia and hepatic insulin resistance in clinic.

Pharmacokinetics and Bioavailability Enhancement of Baicalin: A Review

Baicalin is one of the major bioactive components of Scutellaria radix, a Chinese herb that has been used since ancient times. Baicalin has various pharmacological activities, including antitumor, antimicrobial, and antioxidant, and has wide clinical applications. Baicalin displays a distinct pharmacokinetic profile including gastrointestinal hydrolysis, enterohepatic recycling, carrier-mediated transport, and complicated metabolism. The in vivo disposition of baicalin is affected by combinations of other herbs and baicalin can interact with other co-administered drugs due to competition between metabolic enzymes and protein binding. Furthermore, baicalin exhibits altered pharmacokinetic properties under different pathological conditions. Due to its low bioavailability, emerging novel baicalin preparations including nano/micro-scale baicalin delivery systems show better absorption and higher bioavailability in preclinical studies, and show promise for future clinical applications. Thus, this current review offers a comprehensive report on the pharmacokinetic behavior of baicalin and strategies to improve its bioavailability.

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.

Baicalin alleviates hyperglycemia-induced endothelial impairment 1 via Nrf2

Baicalin is the major component found in Scutellaria baicalensis root, a widely used herb in traditional Chinese medicine, which exhibits strong anti-inflammatory, anti-viral and anti-tumor activities. The present work was devoted to elucidate the molecular and cellular mechanisms underlying the protective effects of Baicalin against diabetes-induced oxidative damage, inflammation and endothelial dysfunction. Diabetic mice, induced by streptozotocin (STZ), were treated with intraperitoneal Baicalin injections. Human umbilical vein endothelial cells (HUVECs) were cultured either in normal glucose (NG, 5.5 mM) or high glucose (HG, 33 mM) medium in the presence or absence of Baicalin for 72 h. We observed an obvious inhibition of hyperglycemia-triggered oxidative damage and inflammation in HUVECs and diabetic aortal vasculature by Baicalin, along with restoration of hyperglycemia-impaired nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway activity. However, the protective effects of Baicalin almost completely abolished in HUVECs transduced with shRNA against Nrf2, but not with nonsense shRNA. Mechanistic studies demonstrated that HG decreased Akt and GSK3B phosphorylation, restrained nuclear export of Fyn and nuclear localization of Nrf2, blunted Nrf2 downstream target genes, and subsequently induced oxidative stress in HUVECs. However, those destructive cascade, were well prevented by Baicalin in HUVECs. Furthermore, LY294002 and ML385 (inhibitor of PI3K and Nrf2) attenuated Baicalin mediated Nrf2 activation and the ability of facilitates angiogenesis in vivo and ex vivo. Taken together, the endothelial protective effect of Baicalin under hyperglycemia condition could be partly attributed to its role in downregulating reactive oxygen species (ROS) and inflammation via the Akt/GSK3B/Fyn-mediated Nrf2 activation.

O-GlcNAc-modified SNAP29 inhibits autophagy-mediated degradation via the disturbed SNAP29-STX17-VAMP8 complex and exacerbates myocardial injury in type I diabetic rats

The O-linked β-N-acetylglucosamine (O-GlcNAc) modification and autophagy are associated with diabetic myocardial injury, however, the molecular mechanisms between the two processes remain to be fully elucidated. The purpose of the present study was to elucidate the molecular regulation of autophagy by O-GlcNAc-modified synaptosomal-associated protein 29 (SNAP29) in diabetic myocardial injury. A rat model of type I diabetes was established via intraperitoneal injection of streptozotocin (STZ; 55 mg/kg). Significant increases in the O-GlcNAc modification and accumulation of the autophagy markers microtubule-associated protein 1 light chain 3α II/I and P62, which suggest that autophagic flux is inhibited, were observed in rats 8 weeks following STZ induction. Subsequently, the selective O-GlcNAcase inhibitor, thiamet G, increased the level of O-GlcNAc modification, which further disrupted autophagic flux; deteriorated cardiac diastolic function, as indicated by an increased left ventricular filling peak velocity/atrial contraction flow peak velocity ratio shown by echocardiography; and exacerbated myocardial abnormalities, as characterized by cardiomyocyte disorganization and fat and interstitial fibrosis accumulation. By contrast, 6-diazo-5-oxo-L-norleucine, an inhibitor of glucosamine fructose-6-phosphate aminotransferase isomerizing 1, acted as an O-GlcNAc antagonist and reduced the level of O-GlcNAc modification, which maintained autophagic flux and improved cardiac diastolic function. In vitro, high glucose (25 mM) was used to stimulate primary neonatal rat cardiomyocytes (NRCMs). Consistent with the myocardium of diabetic rats, it was also shown in the NRCMs that O-GlcNAc modification of SNAP29 negatively regulated autophagic flux. The application of the short hairpin RNA interference lysosome-associated membrane protein (LAMP2) and the autophagy inhibitor 3-methyladenine demonstrated that high glucose inhibited autophagy-mediated degradation rather than affected the initial stage of autophagy. Finally, co-immunoprecipitation was used to determine the role of the O-GlcNAc-modified substrate protein SNAP29, which acted as an SNAP29-syntaxin-17 (STX17)-vesicle-associated membrane protein 8 (VAMP8) complex during disease progression. The present study is the first, to the best of our knowledge, to demonstrate that SNAP29 is an O-GlcNAc substrate and that an increase in O-GlcNAc-modified SNAP29 inhibits SNAP29-STX17-VAMP8 complex formation, thereby inhibiting the degradation of autophagy and exacerbating myocardial injury in type I diabetic rats.

Beneficial effect of baicalin on insulin sensitivity in adipocytes of diet-induced obese mice

AIMS

Although baicalin has been shown to increase glucose uptake and insulin sensitivity in skeletal muscle of mice, there is no literature available about the effect of baicalin on insulin sensitivity in adipocytes of diet-induced obese mice.

METHODS

In the present study, diet-induced obese mice were given 50 mg/kg baicalin intraperitoneally (i.p.) once a day for 21 days, and 3T3-L1 cells were treated with 100, 200, 400 μM baicalin for 3 h. Then insulin resistance indexes and insulin signal protein levels were examined to elucidate whether baicalin increased glucose uptake and GLUT4 translocation in adipocytes of diet-induced obese mice.

RESULTS

The present findings showed that administration of baicalin decreased food intake, body weight, HOMA-IR and p-p38 MAPK and pERK levels, but enhanced pAKT and PGC-1α contents, as well as GLUT4 mRNA, PGC-1α mRNA expression in adipocytes, and reversed high fat diet-induced glucose intolerance, hyperglycemia and insulin resistance in diet-induced obese mice. Moreover, baicalin treatment increased GLUT4 concentration in plasma membranes of adipocytes.

CONCLUSIONS

These data demonstrated that baicalin accelerated GLUT4 translocation from intracellular membrane compartments to plasma membranes in adipocytes. Baicalin plays a significant role in elevation of glucose uptake and insulin sensitivity to promote glucose clearance.

Effect of baicalin on GLUT4 expression and glucose uptake in myotubes of rats

AIMS

Although baicalin could attenuate obesity-induced insulin resistance, the detailed mechanism of baicalin on glucose uptake has not been sufficiently explored as yet. The aim of this study was to survey if baicalin might facilitate glucose uptake and to explore its signal mechanisms in L6 myotubes.

MATERIALS AND METHODS

L6 myotubes were treated with 100, 200, 400 μM baicalin for 6 h, 12 h and 24 h in this study. Then 2-NBDG and insulin signal protein levels in myotubes of L6 cells were examined.

KEY FINDINGS

We discovered that administration of baicalin enhanced GLUT4, PGC-1α, pP38MAPK, pAKT and pAS160 contents, as well as GLUT4 mRNA and PGC-1α mRNA levels in L6 myotubes. The beneficial metabolic changes elicited by baicalin were abrogated in myotubes of L6 by P38MAPK or AKT inhibitors.

SIGNIFICANCE

These results suggest that baicalin promoted glucose uptake in myotubes by differential regulation on P38MAPK and AKT activity. In conclusion, these data provide insight that baicalin is a powerful and promising agent for the treament of hyperglycemia via AKT/AS160/GLUT4 and P38MAPK/PGC1α/GLUT4 pathway.

Effect of Gegen Qinlian Decoction on Cardiac Gene Expression in Diabetic Mice

The aim of this research is to investigate the therapeutic effect of GGQL decoction on cardiac dysfunction and elucidate the pharmacological mechanisms. db/db mice were divided into DB group or GGQL group, and WT mice were used as control. All mice were accessed by echocardiography. And the total RNA of LV tissue samples was sequenced, then differential expression genes were analyzed. The RNA-seq results were validated by the results of RT-qPCR of 4 genes identified as differentially expressed. The content of pyruvate and ceramide in myocardial tissue was also measured. The results showed that GGQL decoction could significantly improve the diastolic dysfunction, increase the content of pyruvate, and had the trend to reduce the ceramide content. The results of RNA-seq showed that 2958 genes were differentially expressed when comparing the DB group with the WT group. Among them, compared with the DB group, 26 genes were differentially regulated in the GGQL group. The expression results of 4 genes were consistent with the RNA-seq results. Our study reveals that GGQL decoction has a therapeutic effect on diastolic dysfunction of the left ventricular and the effect may be related to its role in promoting myocardial glycolysis and decreasing the content of ceramide.

Baicalin and its metabolites suppresses gluconeogenesis through activation of AMPK or AKT in insulin resistant HepG-2 cells

Scutellaria baicalensis Georgi (S. baicalensis), as a traditional Chinese herbal medicine, is an important component of several famous Chinese medicinal formulas for treating patients with diabetes mellitus. Baicalin (BG), a main bioactive component of S. baicalensis, has been reported to have antidiabetic effects. However, pharmacokinetic studies have indicated that BG has poor oral bioavailability. Therefore, it is hard to explain the pharmacological effects of BG in vivo. Interestingly, several reports show that BG is extensively metabolized in rats and humans. Therefore, we speculate that the BG metabolites might be responsible for the pharmacological effects. In this study, BG and its three metabolites (M1-M3) were examined their effects on glucose consumption in insulin resistant HepG-2 cells with a commercial glucose assay kit. Real-time PCR and western blot assay were used to confirm genes and proteins of interest, respectively. The results demonstrate that BG and its metabolites (except for M3) enhanced the glucose consumption which might be associated with inhibiting the expression of the key gluconeogenic genes, including glucose-6-phosphatase (G6Pase), phosphoenolypyruvate carboxykinase (PEPCK) and glucose transporter 2 (GLUT2). Further study found that BG and M1 could suppress hepatic gluconeogenesis via activation of the AMPK pathway, while M2 could suppress hepatic gluconeogenesis via activation of the PI3K/AKT signaling pathway. Taken together, our findings suggest that both BG and its metabolites have antihyperglycemic activities, and might be the active forms of oral doses of BG in vivo.

Baicalin against obesity and insulin resistance through activation of AKT/AS160/GLUT4 pathway

Obesity may cause several metabolic complications, including insulin resistance and type 2 diabetes mellitus. Despite great advances in medicine, people still keep exploring novel and effective drugs for treatment of obesity and insulin resistance. The aim of this study was to survey if baicalin might ameliorate obesity-induced insulin resistance and to explore its signal mechanisms in skeletal muscles of mice. Diet-induced obese (DIO) mice were given 50 mg/kg baicalin intraperitoneally (i.p.) once a day for 21 days, and C2C12 myotubes were treated with 100, 200, 400 μM baicalin for 12 h in this study. Then insulin resistance indexes and insulin signal protein levels in skeletal muscles were examined. We discovered that administration of baicalin decreased food intake, body weight, HOMA-IR and NT-PGC-1α levels, but enhanced GLUT4, PGC-1α, pP38MAPK, pAKT and pAS160 contents, as well as GLUT4 mRNA, PGC-1α mRNA, PPARγ mRNA, GLUT1 mRNA expression in skeletal muscles of obese mice and myotubes of C2C12 cells, and reversed high fat diet-induced glucose and insulin intolerance, hyperglycemia and insulin resistance in the mice. These results suggest that baicalin is a powerful and promising agent for treatment of obesity and insulin resistance via Akt/AS160/GLUT4 and P38MAPK/PGC1α/GLUT4 pathway.

Differential regulation of baicalin and scutellarin on AMPK and Akt in promoting adipose cell glucose disposal

Baicalin and scutellarin, two flavonoid glucuronic acids isolated from Scutellaria baicalensis, exhibit beneficial effects on glucose homeostasis. Baicalin and scutellarin are similar in structure except scutellarin has an additional hydroxyl at composition C-4'. In this work, we observed that baicalin and scutellarin promoted glucose disposal in mice and in adipocytes. Baicalin selectively increased phosphorylation of AMP-activated kinase (AMPK), while scutellarin selectively enhanced Akt phosphorylation. Both of them increased AS160 phosphorylation and glucose uptake in basal condition. AMPK inhibitor or knockdown of AMPK by siRNA blocked baicalin-induced AS160 phosphorylation and glucose uptake, but showed no effects on scutellarin. In contrast, Akt inhibitor and knockdown of Akt with siRNA decreased scutellarin-stimulated glucose uptake but had no effects on baicalin. The molecular dynamic simulations analysis showed that the binding energy of baicalin to AMPK (-34.30kcal/mol) was more favorable than scutellarin (-21.27kcal/mol), while the binding energy of scutellarin (-29.81kcal/mol) to Akt was much more favorable than baicalin (4.04kcal/mol). Interestingly, a combined treatment with baicalin and scutellarin acted synergistically to enhance glucose uptake in adipocytes (combination index: 0.94-0.046). In conclusion, baicalin and scutellarin, though structurally similar, promoted glucose disposal in adipocytes by differential regulation on AMPK and Akt activity. Our data provide insight that multicomponent herbal medicines may act synergistically on multiple targets.

Nanostructured Lipid Carriers Loaded with Baicalin: An Efficient Carrier for Enhanced Antidiabetic Effects

Context:

Recent studies have demonstrated that baicalin has antihyperglycemic effects by inhibiting lipid peroxidation. Baicalin is low hydrophilic and poorly absorbed after oral administration. Thus, a suitable formulation is highly desired to overcome the disadvantages of baicalin.

Objective:

The objective of this work was to prepare baicalin-loaded nanostructured lipid carriers (B-NLCs) for enhanced antidiabetic effects.

Materials and Methods:

B-NLCs were prepared by high-pressure homogenization method using Precirol as the solid lipid and Miglyol as the liquid lipid. The properties of the NLCs, such as particle size, zeta potential (ZP), and drug encapsulation efficiency (EE), were investigated. The morphology of NLCs was observed by transmission electron microscopy. In addition, drug release and antidiabetic activity were also studied.

Results:

The results revealed that B-NLCs particles were uniformly in the nanosize range and of spherical morphology with a mean size of 92 ± 3.1 nm, a ZP of −31.35 ± 3.08 mV, and an EE of 85.29 ± 3.42%. Baicalin was released from NLCs in a sustained manner. In addition, B-NLCs showed a significantly higher antidiabetic efficacy compared with baicalin.

Conclusion:

B-NLCs described in this study are well-suited for the delivery of baicalin.

SUMMARY

Currently, herbal medicines have attracted increasing attention as a complementary approach for type 2 diabetes

Baicalin has antihyperglycemic effects by inhibiting lipid peroxidation

A suitable formulation is highly desired to overcome the disadvantages (poor solubility and low bioavailability) of baicalin

Nanostructured lipid carriers could enhance the antidiabetic effects of baicalin.

Abbreviations used: B-NLCs: Baicalin-Loaded Nanostructured Lipid Carriers, B-SUS: Baicalin Water Suspension, EE: Encapsulation Efficiency, FBG: Fasting Blood Glucose, HbAlc: Glycosylated Hemoglobin, HPLC: High-performance Liquid Chromatography; NLCs: Nanostructured Lipid Carriers, PI: Polydispersity Index, SD: Sprague-Dawley, SLNs: Solid lipid nanoparticles, STZ: Streptozotocin, TC: Total cholesterol, TEM: Transmission Electron Microscope, TG: Total Triglyceride, ZP: Zeta Potential.

Comparative anti-inflammatory and lipid-normalizing effects of metformin and omega-3 fatty acids through modulation of transcription factors in diabetic rats

BACKGROUND

Emerging evidence suggests beneficial effects of omega-3 fatty acids on diabetic complications. The present study compared the progressive effects of metformin and flax/fish oil on lipid metabolism, inflammatory markers, and liver and renal function test markers in streptozotocin-nicotinamide-induced diabetic rats.

METHODS

Streptozotocin-induced diabetic rats were randomized into control and four diabetic groups: streptozotocin (STZ), metformin (200 mg/kg body weight (b.w)/day (D)), flax and fish oil (500 mg/kg b.w/D).

RESULTS

Metformin and flax and fish oil exhibited increased expression of transcription factor peroxisome proliferator-activated receptor γ while the treatment downregulated sterol regulatory element-binding protein 1 and nuclear factor kβ as compared to those of the STZ group. Apart from modulation of transcription factor expression, the expression of fatty acid synthase, long chain acyl CoA synthase, and malonyl-CoA-acyl carrier protein transacylase was lowered by flax/fish oil treatment. Serum cholesterol, triglycerides, and VLDL were also significantly reduced in the treatment groups as compared to those in the STZ group. Although pathological abnormalities were seen in the liver and kidneys of rats on metformin, no significant changes in liver/renal function markers were observed at day 15 and day 30 of the treatment groups. Flax/fish oil had protective effects toward pathological abnormalities in the liver and kidney. Flax/fish oil improved lipid profile and alkaline phosphatase at day 30 as compared to that at day 15.

CONCLUSIONS

The present study demonstrates potential beneficial effects of metformin and flax/fish oil intervention in improving serum lipid profile by regulating the expression of transcription factors and genes involved in lipid metabolism in diabetic rats. In addition, these interventions also lowered the expression of atherogenic cytokines. The protective effects of flax/fish oil are worth investigating in human subjects on metformin monotherapy.

Baicalin alleviates diabetes‑associated cognitive deficits via modulation of mitogen-activated protein kinase signaling, brain‑derived neurotrophic factor and apoptosis

Baicalin is an important active component of the medicinal herb Scutellaria baicalensis Georgi and has shown a variety of pharmacological actions. The present study aimed to evaluate the neuroprotective effects of baicalin against diabetes‑associated cognitive deficits (DACD) in rats and to elucidate the potential molecular mechanisms of action. A rat model of diabetes mellitus was prepared by intraperitoneal injection of streptozotocin. After the successful establishment of the diabetic rat model, baicalin (50, 100 and 200 mg/kg) or vehicle was administrated for seven weeks. Learning and memory function were assessed using the Morris water maze test. At the end of the experiment, the activities of acetylcholinesterase (AChE) and choline acetylase (ChAT) were determined using commercial kits. Furthermore, the expression of proteins involved in mitogen‑activated protein kinase (MAPK) cascades [extracellular signal‑regulated kinase (ERK), c‑Jun N‑terminal kinase (JNK) and p38], brain‑derived neurotrophic factor (BDNF) and apoptosis‑associated proteins [caspase‑3, B-cell lymphoma 2 (Bcl‑2) and Bcl-2-associated X protein (Bax)] were detected by western blot analysis. Caspase‑3 activity was also analyzed using a commercial kit. The results demonstrated that diabetic rats exhibited decreases in body weight, decreases in the percentage of time spent in the target quadrant and the number of times of crossing the platform in the water maze test, as well as decreases in neuronal survival, ChAT, phosphorylated (p)ERK, BDNF and Bcl‑2. Furthermore, diabetic rats showed increases in escape latency and mean path length in the water maze test, increases in the levels of hippocampal AChE, p‑JNK, p‑p38, caspase‑3 and Bax as well as plasma glucose. However, in diabetic rats treated with baicalin, all of the abovementioned observations were obviously reversed. The findings suggested that baicalin exerts neuroprotective effects against DACD via modulation of MAPK cascades, BDNF and apoptosis.

Development of immunoaffinity chromatography to specifically knockout baicalin from Gegenqinlian Decoction

Specific knockout technology provides a powerful tool to confirm the role of target compounds in a plant or its derived prescriptions, and this principle is the same as that with knockout genes. In this study, we generated an immunoaffinity column conjugated with an anti-baicalin monoclonal antibody and then loaded Gegenqinlian Decoction extracts, followed by washing with deionized water and an elution solvent. The results of the high-performance liquid chromatography fingerprints and high-performance liquid chromatography with mass spectrometry showed that the immunoaffinity column was able to specifically knockout baicalin, oroxylin A-7-O-glucuronide, wogonoside, wogonin, and baicalein from Gegenqinlian Decoction. A reliable one-step method to specifically knockout baicalin was established with an immunoaffinity column. Gegenqinlian Decoction and its knocked-out fraction induced the expression of superoxide dismutase and were compared in human umbilical vein endothelial cells cultured with a high glucose concentration; the results showed that the Gegenqinlian Decoction and its knocked-out fraction showed no significant difference, which indicated that the baicalin, oroxylin A-7-O-glucuronide, wogonoside, wogonin, and baicalein that were knocked out by the immunoaffinity column might not be key compounds for the induction of Gegenqinlian Decoction superoxide dismutase secretion.

Comparative pharmacokinetic investigation on baicalin and wogonoside in type 2 diabetic and normal rats after oral administration of traditional Chinese medicine Huanglian Jiedu decoction

ETHNOPHARMACOLOGICAL RELEVANCE

Huanglian Jiedu decoction (HLJDD) is used traditionally in China for the treatment of diabetes mellitus in clinical practice, which has been proved to be effective. The purpose of this study was to investigate the pharmacokinetic characteristics (especially the area under the curve, AUC) of baicalin and wogonoside in type 2 diabetic rats after oral administration of HLJDD extract and to explore its possible mechanism.

MATERIALS AND METHODS

HLJDD extract and Radix scutellariae extract were prepared and the contents of baicalin and wogonoside contained in two extracts were assayed with high performance liquid chromatography (HPLC). Type 2 diabetic rats were induced by high fat diet and intraperitoneal injection of streptozotocin. Pharmacokinetics of baicalin and wogonoside in type 2 diabetic and normal control rats after oral administration of HLJDD extract or Radix scutellariae extract were investigated. Pharmacokinetics of baicalin in type 2 diabetic and normal rats after oral administration of pure baicalin was also investigated.

RESULTS

The pharmacokinetic parameters (especially AUCs) of baicalin and wogonoside in type 2 diabetic rats after oral administration of HLJDD extract were remarkably different from those in normal rats. And the alterations of the AUCs of baicalin and wogonoside in type 2 diabetic rats after oral administration of Radix scutellariae extract were similar to those after oral administration of HLJDD extract. Moreover, the increase of the AUC of baicalin in type 2 diabetic rats after oral administration of pure baicalin was similar to that after oral administration of HLJDD extract or Radix scutellariae extract.

CONCLUSION

The pharmacokinetic behaviors of baicalin and wogonoside (especially the systemic exposure [AUCs] of baicalin and wogonoside) were significantly altered in type 2 diabetic rats after orally administrated HLJDD extract. And the increased AUCs of baicalin and wogonoside in type 2 diabetic rats after oral administration of HLJDD extract resulted from neither the effects of other herbs contained in HLJDD nor the effects of other components contained in Radix scutellariae. It might result from the effects of the pathological status of type 2 diabetes mellitus.

Comparative metabolites in plasma and urine of normal and type 2 diabetic rats after oral administration of the traditional Chinese scutellaria-coptis herb couple by ultra performance liquid chromatography-tandem mass spectrometry

Scutellaria-coptis herb couple is widely used traditional Chinese medicine (TCM) in treating type 2 diabetes; however, the in vivo integrated metabolism of its main bioactive components in type 2 diabetic rats remains unknown. In this paper, ultra-performance liquid chromatography (UPLC) coupled to quadrupole time-of-flight (Q-TOF) and the MetaboLynx™ software combined with mass defect filtering (MDF) together provided unique high throughput capabilities for drug metabolism study with excellent MS mass accuracy and enhanced MS(E) data acquisition. This rapid automated analysis method was successfully applied for screening and identification of the absorbed and metabolized constituents after oral administration of scutellaria-coptis extract to rats. The results showed that a total of 14 metabolites of two parent compounds were detected and tentatively identified in vivo based on the characteristics of their protonated ions. Main parent components of scutellaria-coptis extract such as baicalin and berberine were absorbed into the blood circulation of the rats. Differences of metabolite classes were not observed between normal and type 2 diabetic rat plasma and urine samples. However, the concentrations of baicalin and methylated berberine in type 2 diabetic rat plasma were much higher than those in normal sample. While, the concentrations of these two compounds in type 2 diabetic rat urine were remarkably lower than those in normal sample. This helped maintain a high blood drug concentration which might be beneficial for the treatment of type 2 diabetes. Additionally, the developed method was simple and reliable, revealing that it could be used to rapid screen and propose the structures of active components responsible for pharmacological effects of scutellaria-coptis and to better clarify its action mechanism. This work suggests that the integrative metabolism approach makes a useful template for drug metabolism research of TCMs.

Comparative metabolism of Radix scutellariae extract by intestinal bacteria from normal and type 2 diabetic mice in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) has been used in clinical practice for several thousand years. TCM has played an indispensable role in the prevention and treatment of disease, especially the complicated and chronic ones. In TCMs, many ingredients which are known to have biological effects just pass through the gut, they do not get into the bloodstream. Study on interactions of these active ingredients with the intestinal bacteria is very helpful to unravel how TCM works. Radix scutellariae was widely used alone or in combination with other medicinal herbs to the treatment of type 2 diabetes mellitus for a long time in China even in Asia. Additionally, the incidence of type 2 diabetes is closely related to the changes of intestinal flora. In this paper, the metabolism of baicalin in Radix scutellariae extract by normal and type 2 diabetic mice intestinal bacteria were firstly investigated.

MATERIALS AND METHODS

Ultra performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/QTOF-MS) technique combined with Metabolynx(TM) software was used for analysis of the metabolic profile of baicalin in Radix scutellariae extracts by the intestinal bacteria from normal and type 2 diabetic mice.

RESULTS

The amount of baicalin׳s aglycone (baicalein) in type 2 diabetic mice samples were remarkably more than that in normal mice samples and oroxylin A only existed in type 2 diabetic mice samples. Intestinal bacteria produced not only a small amount of baicalein, but also some conjugates such as hydrogenated baicalin and methylated baicalin.

CONCLUSIONS

We proposed that β-d-glucuronidases contributed to the deglycosylation prior to absorption. Intestinal bacteria from pathological state mice produced more baicalein, which was well absorbed contributing to the treatment of type 2 diabetes. Additionally, the pharmacological effects of oroxylin A were associated with type 2 diabetes. Hence, the production of metabolites of baicalin might influence the effects of traditional medicines. Thus the study on the metabolism of baicalin by intestinal bacteria from normal and type 2 diabetic mice was of great importance to understanding the effects of traditional medicines. Furthermore, this work demonstrated the potential of the ultra performance liquid chromatography/quadrupole time-of-flight mass spectrometry approach with MetaboLynx for quite rapid, simple, reliable and automated identification of metabolites of natural products.

Adipocyte dysfunction in rats with streptozotocin-nicotinamide-induced diabetes

Administration of streptozotocin (STZ) and nicotinamide (NA) to adult rats allows for the induction of mild diabetes. However, this experimental model has not been fully characterized. This study was undertaken to determine the metabolic and secretory activity of adipose tissue in rats with STZ-NA-induced diabetes. Experiments were performed using epididymal adipocytes isolated from control and mildly diabetic rats. Lipogenesis, glucose transport as well as glucose and alanine oxidation, lipolysis, anti-lipolysis, cAMP levels and adipokine secretion were compared in cells isolated from the control and diabetic rats. Lipogenesis, glucose transport and oxidation were diminished in the adipocytes of diabetic rats compared with the fat cells of control animals. However, alanine oxidation appeared to be similar in the cells of non-diabetic and diabetic animals. Lipolytic response to low epinephrine concentrations was slightly increased in the adipocytes of diabetic rats; however, at higher concentrations of the hormone, lipolysis was similar in both groups of cells. The epinephrine-induced rise in cAMP levels was higher in the adipocytes of STZ-NA-induced diabetic rats, even in the presence of insulin. Lipolysis stimulated by dibutyryl-cAMP did not significantly differ, whereas anti-lipolytic effects of insulin were mildly decreased in the cells of diabetic rats. Secretion of adiponectin and leptin was substantially diminished in the adipocytes of diabetic rats compared with the cells of control animals. Our studies demonstrated that the balance between lipogenesis and lipolysis in the adipose tissue of rats with mild diabetes induced by STZ and NA is slightly shifted towards reduced lipid accumulation. Simultaneously, adiponectin and leptin secretion is significantly impaired.

Protection of long-term treatment with huang-lian-jie-du-tang on vascular endothelium in rats with type 2 diabetes mellitus

BACKGROUND

Huang-Lian-Jie-Du-Tang (HLJDT) is the classical traditional Chinese recipe for heat clearance and detoxification and is used in diabetic patients in the clinical practice of traditional Chinese medicine.

OBJECTIVE

The aim of this study was to evaluate the protective effects of long-term treatment with HLJDT on vascular endothelial function in rats with type 2 diabetes mellitus (T2DM).

METHODS

The male T2DM model rats were induced by intraperitoneal injection of low-dose streptozotocin plus a high-fat and high-calorie laboratory diet. The T2DM animals were randomly divided into the T2DM model group, the low-dose HLJDT group (0.42 g/kg/d), and the high-dose HLJDT group (1.25 g/kg/d).

RESULTS

Administration of HLJDT (0.42 or 1.25 g/kg/d) for 8 weeks decreased the levels of serum fasting blood glucose, malondialdehyde, and vascular tissue interleukin 6 but raised the level of serum superoxide dismutase compared with the T2DM model group in a dose-dependent manner. In addition, HLJDT treatment restored the impaired endothelial-dependent vascular relaxation in aortic preparations from the T2DM model group in a dose-dependent manner.

CONCLUSIONS

Early and long-term treatments with HLJDT could have anti-inflammatory, antioxidant properties and could protect vascular endothelium from the cardiovascular complications associated with T2DM.

A network pharmacology approach to determine active compounds and action mechanisms of ge-gen-qin-lian decoction for treatment of type 2 diabetes

Traditional Chinese medicine (TCM) herbal formulae can be valuable therapeutic strategies and drug discovery resources. However, the active ingredients and action mechanisms of most TCM formulae remain unclear. Therefore, the identification of potent ingredients and their actions is a major challenge in TCM research. In this study, we used a network pharmacology approach we previously developed to help determine the potential antidiabetic ingredients from the traditional Ge-Gen-Qin-Lian decoction (GGQLD) formula. We predicted the target profiles of all available GGQLD ingredients to infer the active ingredients by clustering the target profile of ingredients with FDA-approved antidiabetic drugs. We also applied network target analysis to evaluate the links between herbal ingredients and pharmacological actions to help explain the action mechanisms of GGQLD. According to the predicted results, we confirmed that a novel antidiabetic ingredient from Puerariae Lobatae radix (Ge-Gen), 4-Hydroxymephenytoin, increased the insulin secretion in RIN-5F cells and improved insulin resistance in 3T3-L1 adipocytes. The network pharmacology strategy used here provided a powerful means for identifying bioactive ingredients and mechanisms of action for TCM herbal formulae, including Ge-Gen-Qin-Lian decoction.

The safety and effectiveness of TM81, a Chinese herbal medicine, in the treatment of type 2 diabetes: a randomized double-blind placebo-controlled trial

AIM

TM81 (or Tang-Min-Ling-Wan) is a Chinese medicine. Previous studies suggested that this medicine is effective for treating type 2 diabetes. This controlled trial evaluated the safety and effectiveness of TM81 in the treatment of type 2 diabetic patients.

METHODS

This study was a large-scale controlled clinical trial to evaluate the safety and effectiveness of TM81 on type 2 diabetes. After a 2-week run-in period, 480 overweight type 2 early-stage diabetic patients [35-65 years old, HbA1c ≥ 7.0%, fasting plasma glucose (FPG) 7.0-13.9 mM or 2 h plasma glucose (PG) > 11.1 mM, body mass index (BMI) ≥ 24 kg/m(2)] were enrolled. These patients were divided into a TM81 group and placebo group in a 3 : 1 ratio. The subjects received 6 g TM81 or placebo, three times daily for 12 weeks.

RESULTS

After treatment, the HbA1c decrease was 1.02% in the TM81 group versus 0.47% in the placebo group. The FPG decreased 0.8 ± 0.1 mM in the TM81 group versus an increase of 0.2 ± 0.2 mM in the placebo group. The PG decreased 2.7 ± 0.3 mM in the TM81 group versus a decrease of 0.9 ± 0.4 mM in the placebo group (all p < 0.05). The TM81 was more effective for patients with higher baseline HbA1c levels. The TM81 group also showed improved β-cell function and increased homeostatic model assessment (HOMA)-β. In addition, body weight, BMI and waist circumference of subjects in the TM81 group were reduced, and the symptoms related to diabetes were improved. There were no significant differences in the types and frequency of adverse reactions between the two groups.

CONCLUSIONS

The data showed that TM81 is effective in controlling blood glucose level and is safe to use in patients with early-stage type 2 diabetes.

Anti-asthmatic effects of baicalin in a mouse model of allergic asthma

The aim of the study was to investigate the anti-asthmatic effects of baicalin (BA) and the possible mechanisms. Asthma model was established by ovalbumin (OVA) intraperitoneal injection. A total of 60 mice were randomly assigned to six experimental groups: control, model, dexamethasone (2 mg/kg), and BA (10 mg/kg, 20 mg/kg, 40 mg/kg). Airway resistance (RI) and lung compliance (Cdyn) were measured, histological studies were evaluated by the hematoxylin and eosin staining, Th1/Th2, OVA-specific serum, and BALF IgE levels and Th17 cytokines were evaluated by enzyme-linked immunosorbent assay, and Th17 cells was evaluated by flow cytometry (FCM). Our study demonstrated that BA inhibited OVA-induced increases in RI and eosinophil count; interleukin (IL)-4, IL-17A levels, and Cdyn were recovered and increased IFN-γ level in bronchoalveolar lavage fluid. Histological studies demonstrated that BA substantially inhibited OVA-induced eosinophilia in lung tissue and airway tissue. FCM studies demonstrated that BA substantially inhibited Th17 cells. These findings suggest that BA may effectively ameliorate the progression of asthma and could be used as a therapy for patients with allergic asthma.

Antihyperglycemic effect of the traditional Chinese scutellaria-coptis herb couple and its main components in streptozotocin-induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellaria-coptis herb couple (SC) is the main herb couple in many traditional Chinese compound formulas used for the treatment of diabetes mellitus, which has been used to treat diabetes mellitus for thousands of years in China. In this study we provide experimental evidence for the clinical use of SC in the treatment of diabetes mellitus.

AIM OF THE STUDY

To confirm the anti-diabetic effect of SC extract and its main components, and to explore its mechanism from the effect on intestinal disaccharidases by in vivo and in vitro experiment.

MATERIALS AND METHODS

SC extract was prepared and the main components (namely berberine and baicalin) contained in the extract were assayed with high performance liquid chromatography (HPLC). And diabetic model rats were induced by intraperitoneal injection of streptozotocin (STZ). After grouped randomly, diabetic rats were administered SC extract, berberine, baicalin, berberine+baicalin, acarbose and vehicle for 33d, respectively. Body weight, food intake, urine volume, urine sugars, fasting plasma glucose and fasting plasma insulin were monitored to evaluate the antidiabetic effects on diabetic rats. Intestinal mucosa homogenate was prepared and the activities of intestinal disaccharidases were assayed. Moreover, oral sucrose tolerance test (OSTT) was performed and the inhibitory effects of SC extract and its main components (berberine and baicalin) on the maltase and sucrase in vitro was evaluated.

RESULTS

After the treatment of SC extract and its main components, the body weight and the fasting plasma insulin level were found to be increased while food intake, urine volume, urine sugars and fasting plasma were decreased. OSTT showed that SC extract and its main components could lower the postprandial plasma glucose level of diabetic rats. Furthermore, SC extract and its main components could inhibit the activities of intestinal disaccharidases in diabetic rats, whereas only SC extract and berberine could inhibit the activity of maltase in vitro.

CONCLUSIONS

According to our present findings, scutellaria-coptis herb couple (SC) possessed potent anti-hyperglycemic effect on STZ-induced diabetic rats. And SC extract and its main components exerted anti-hyperglycemic effect partly via inhibiting the increased activities of intestinal disaccharidases and elevating the level of plasma insulin in diabetic rats induced by STZ.

CaMKKβ is involved in AMP-activated protein kinase activation by baicalin in LKB1 deficient cell lines

AMP-activated protein kinase (AMPK) plays an important role in mediating energy metabolism and is controlled mainly by two upstream kinases, LKB1 or Ca²⁺/calmodulin-dependent protein kinase kinase-β (CaMKKβ). Previously, we found that baicalin, one of the major flavonoids in a traditional Chinese herb medicine, Scutellaria baicalensis, protects against the development of hepatic steatosis in rats feeding with a high-fat diet by the activation of AMPK, but, the underlying mechanism for AMPK activation is unknown. Here we show that in two LKB1-deficient cells, HeLa and A549 cells, baicalin activates AMPK by α Thr-172 phosphorylation and subsequent phosphorylation of its downstream target, acetyl CoA carboxylase, at Ser-79, to a similar degree as does in HepG2 cells (that express LKB1). Pharmacologic inhibition of CaMKKβ by its selective inhibitor STO-609 markedly inhibits baicalin-induced AMPK activation in both HeLa and HepG2 cells, indicating that CaMKKβ is the responsible AMPK kinase. We also show that treatment of baicalin causes a larger increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i), although the maximal level of [Ca²⁺]_i is lower in HepG2 cells compared to HeLa cells. Chelation of intracellular free Ca²⁺ by EDTA and EGTA, or depletion of intracellular Ca²⁺ stores by the endoplasmic reticulum Ca²⁺-ATPase inhibitor thapsigargin abrogates baicalin-induced activation of AMPK in HeLa cells. Neither cellular ATP nor the production of reactive oxygen species is altered by baicalin. Finally, in HeLa cells, baicalin treatment no longer decreases intracellular lipid accumulation caused by oleic acid after inhibition of CaMKKβ by STO-609. These results demonstrate that a potential Ca²⁺/CaMKKβ dependent pathway is involved in the activation of AMPK by baicalin and suggest that CaMKKβ likely acts as an upstream kinase of AMPK in response to baicalin.