Systematic review and meta-analysis of Coptis chinensis Franch.-containing traditional Chinese medicine as an adjunct therapy to metformin in the treatment of type 2 diabetes mellitus

Background: In China, Coptis chinensis Franch. (Chinese name: Huanglian) prescriptions (HLPs) are prominent hypoglycemic agents used in glycemic control. However, the curative effect of HLPs as adjunctive therapies for type 2 diabetes mellitus (T2DM) has not been evaluated. Based on a systematic review and a meta-analysis, this study was conducted to assess the effects of HLPs combined with metformin as a reinforcing agent for T2DM. Materials and methods: A total of 33 randomized controlled trials (RCTs) reporting on 2,846 cases concerning the use of HLPs in the treatment of T2DM were identified from the China National Knowledge Infrastructure (CNKI), Weipu (VIP), Wanfang, PubMed, Cochrane Library, and EMBASE databases. Primary outcomes included fasting blood glucose (FBG), 2-h postprandial blood glucose (2hPG), glycosylated hemoglobin, type A1c (HbA1c), fasting serum insulin (FINS), and homeostasis model assessment of insulin resistance (HOMA-IR). Secondary outcomes included total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), and gastrointestinal dysfunction (GD). Continuous data were expressed as mean differences (MDs) with 95% confidence intervals (CIs). The methodological quality of the included RCTs was assessed by Cochrane evidence-based medicine systematic evaluation. Statistical analysis was performed using the Review Manager and Stata software. The required information size and treatment benefits were evaluated by trial sequential analysis (TSA). The quality of evidence was rated using the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Results: The results revealed that HLPs are beneficial to improve the following: FBG (MD = -1.16%, 95% CI: -1.24 to -1.07), 2hPG (MD = -1.64%, 95% CI: -1.84 to -1.43), HbA1c (MD = -0.78%, 95% CI:-0.96 to -0.60), FINS (MD = -1.94%, 95% CI: -2.68 to -1.20), HOMA-IR (MD = -0.77%, 95% CI: -1.28 to -0.27), TC (MD = -0.70%, 95% CI: -1.00 to -0.39), TG (MD = -0.57%, 95% CI: -0.74 to -0.40), LDL-c (MD = -0.70%, 95% CI: -0.97 to -0.43), and HDL-c (MD = -0.21%, 95% CI: -0.32 to -0.10) for patients with T2DM. The funnel plot, Egger's test, and trim-and-fill method indicated a moderate publication bias in the results. The TSA showed that the required sample size of HLPs in improving FBG, 2hPG, HbA1c, FINS, HOMA-IR, TC, TG, LDL-c, and HDL-c could sufficiently draw reliable conclusions. GRADE assessment revealed that the quality of the evidence for the effectiveness of HLPs in improving FBG was moderate, but the quality of evidence for 2hPG, HbA1c, FINS, HOMA-IR, TC, TG, LDL-c, and HDL-c was low, and for GD was very low. Conclusion: The systematic review and meta-analysis suggested that HLPs were beneficial for achieving glycemic control. However, HLPs recommended for T2DM patients have yet to be confirmed because of the poor methodological quality of some trials. Therefore, more RCTs with multicenter and double-blind designs are needed to assess the efficacy of HLPs for patients with T2DM.

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.

Hypolipidemic effect of the Chinese polyherbal Huanglian Jiedu decoction in type 2 diabetic rats and its possible mechanism

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. In present investigation, the 3D-HPLC fingerprint of HLJDD and the contents of main components (namely berberine, baicalin and geniposide) contained in the extract of HLJDD were assayed with high performance liquid chromatography (HPLC). Type 2 diabetic rats were induced by high fat diet and streptozotocin. Type 2 diabetic rats were treated with HLJDD extract for 30d, while blood glucose and body weight were monitored during the experiment. At the end of experiment, the levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) were assayed. Intestinal mucosa homogenate was prepared and the activity of pancreatic lipase was analyzed. Moreover, the olive oil loading test (OOLT) was performed and the inhibitory effect of HLJDD extract on the pancreatic lipase in vitro was evaluated. The results showed that, after the treatment of HLJDD extract, the final body weight and the levels of fasting plasma glucose, TC, TG and LDL-C were significantly reduced while the HDL-C level was increased in type 2 diabetic rats. The OOLT showed that HLJDD extract could lower the postprandial plasma TG level of type 2 diabetic rats. The activity of pancreatic lipase in type 2 diabetic rats was decreased after the treatment of HLJDD extract. Moreover, HLJDD extract could inhibit the activity of pancreatic lipase in vitro. In conclusion, the TCM prescription HLJDD possessed potent lipid-modulating effect on type 2 diabetic rats. And HLJDD extract exerted hypolipidemic effects partly via inhibiting the increased activity of intestinal pancreatic lipase in type 2 diabetic rats.

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.

Antihyperglycemic action of sinapic acid in diabetic rats

Sinapic acid is a hydroxycinnamic acid contained in plants. In an attempt to know the hyperglycemic effect of sinapic acid, this study applied streptozotocin (STZ) to induce type 1-like diabetic rats and fed fructose-rich chow to induce type 2-like diabetic rats. Sinapic acid dose-dependently reduced the hyperglycemia of STZ-diabetic rats (9.8 ± 1.8%, 11.6 ± 0.7%, and 19.4 ± 3.2% at 5 mg/kg, 10 mg/kg, and 25 mg/kg, respectively). Also, sinapic acid attenuated the postprandial plasma glucose without changing plasma insulin in rats. Repeated treatment of sinapic acid increased the gene expression of GLUT4 in soleus muscle of STZ-diabetic rats. Moreover, sinapic acid enhanced glucose uptake into isolated soleus muscle and L6 cells (337.0 ± 29.6%). Inhibition of phospholipase C (PLC) using U73122 (1.00 ± 0.02 μg/mg protein) or protein kinase C (PKC) using chelerythrine (0.97 ± 0.02 μg/mg protein) attenuated the sinapic acid-stimulated glucose uptake (1.63 ± 0.02 μg/mg protein) in L6 cells. Otherwise, the reduced glucose infusion rate (GIR) in fructose-rich chow-fed rats was also raised by sinapic acid. Our results suggest that sinapic acid ameliorates hyperglycemia through PLC-PKC signals to enhance the glucose utilization in diabetic rats.

Huang-lian-jie-du-decoction modulates glucagon-like peptide-1 secretion in diabetic rats

AIM OF THE STUDY

Huang-lian-jie-du-decoction (HLJDD), a well-known Chinese herbal formula, has been used for diabetic treatment. The purpose of the study was to investigate whether HLJDD affected glucagon-like peptide (GLP)-1 (7-36) amide level in diabetic rats.

MATERIALS AND METHODS

Streptozotocin (STZ)-induced diabetic rats were treated with HLJDD at low dose (2 g/kg/day) or high dose (4 g/kg/day). After 5-week treatment, GLP-1 (7-36) amide level and insulin level in portal vein and tissues stimulated by oral glucose load were measured by ELISA kits. The proglucagon gene expression in intestinal tracts and the proliferation of intestinal L cell and pancreatic beta cell were measured using RT-PCR and immunohistochemistry techniques, respectively.

RESULTS

It was found that 5-week HLJDD treatment attenuated alteration of glucose level and insulin level in plasma and tissues of diabetic rats induced by STZ, accompanied by improvement of diabetic syndrome. 5-week HLJDD treatment increased GLP-1 (7-36) amide level in portal vein plasma and distal ileum. Further studies showed that 5-week HLJDD treatment increased the mRNA level of proglucagon gene in distal ileum, promoted pancreatic beta cell and intestinal L cell proliferation in a dose-dependent manner.

CONCLUSION

All the results indicated that HLJDD exerted its anti-diabetic effects partly via modulating GLP-1 (7-36) amide level.

[Effects of Huanglian Jiedu Decoction on phosphatidylinositol-3-kinase expression in target tissues of type 2 diabetic rats]

OBJECTIVE

To observe the effects of Huanglian Jiedu Decoction (HLJDD), a traditional Chinese compound herbal medicine, on p85 mRNA and protein expressions of phosphatidylinositol-3-kinase (PI-3K) in target tissues (skeletal muscular and adipose tissues) in rats with type 2 diabetes mellitus (T2DM) and to investigate the molecular mechanism of HLJDD in treating T2DM.

METHODS

The male Wistar rats were injected with streptozotocin (STZ) 30 mg/kg through tail vein, and fed with high-fat and high-caloric diets to induce T2DM. Then the rats were randomly divided into untreated group, aspirin-treated group and HLJDD group, and treated correspondingly. Meanwhile, a group of normal animals without any treatment was set up for normal control group. Ten weeks later, serum fasting blood glucose (FBG), serum fasting insulin (FINS) and oral glucose tolerance test (OGTT) were routinely determined. The expressions of PI-3K p85 mRNA and protein in skeletal muscle and adipose tissue were determined with RT-PCR and Western blotting before and after insulin treatment.

RESULTS

Compared with the untreated group, the FBG and OGTT levels in T2DM rats treated with HLJDD decreased significantly (P<0.05). The FINS in HLJDD group was lower than that in the normal control group (P<0.05), but was not significantly different from that in the untreated group. The PI-3K p85 mRNA and protein expressions in HLJDD group obviously increased, as compared with those in the untreated group.

CONCLUSION

The effect of HLJDD in treating T2DM was probably associated with its improvement of PI-3K p85 mRNA and protein expressions in skeletal muscle and adipose tissue of the T2DM rats.