Mechanisms and Active Compounds Polysaccharides and Bibenzyls of Medicinal Dendrobiums for Diabetes Management.

BACKGROUND: Medicinal dendrobiums are used popularly in traditional Chinese medicine for the treatment of diabetes, while their active compounds and mechanism remain unclear. This review aimed to evaluate the mechanism and active compounds of medicinal dendrobiums in diabetes management through a systematic approach. METHODS: A systematic approach was conducted to search for the mechanism and active phytochemicals in Dendrobium responsible for anti-diabetic actions using databases PubMed, Embase, and SciFinder. RESULTS: Current literature indicates polysaccharides, bibenzyls, phenanthrene, and alkaloids are commonly isolated in Dendrobium genusin which polysaccharides and bibenzyls are most aboundant. Many animal studies have shown that polysaccharides from the species of Dendrobium provide with antidiabetic effects by lowering glucose level and reversing chronic inflammation of T2DM taken orally at 200 mg/kg. Dendrobium polysaccharides protect pancreatic ß-cell dysfunction and insulin resistance in liver. Dendrobium polysaccharides up-regulate the abundance of short-chain fatty acid to stimulate GLP-1 secretion through gut microbiota. Bibenzyls also have great potency to inhibit the progression of the chronic inflammation in cellular studies. CONCLUSION: Polysaccharides and bibenzyls are the major active compounds in medicinal dendrobiums for diabetic management through the mechanisms of lowering glucose level and reversing chronic inflammation of T2DM by modulating pancreatic ß-cell dysfunction and insulin resistance in liver as a result from gut microbita regulation.

Chinese Propolis Inhibits the Proliferation of Human Gastric Cancer Cells by Inducing Apoptosis and Cell Cycle Arrest.

Special Chinese propolis sourced from the Changbai Mountains (CBMP) in Northeast China is rich in specific flavonoids and phenolic acids and its bioactivity has not been reported. This study aimed to investigate the antiproliferative effect of CBMP on cancer cells and its molecular mechanisms. Different cancer cell lines were treated with the ethanol extracts of CBMP for 24 hours before the cell viability and mechanism measurements. The results showed CBMP had weak activities against human pancreatic cancer cell PANC1, human lung cancer cell A549, human colon cancer cell HCT116, human liver cancer cell HepG2, human bladder cancer cell T24, and human breast cancer cell MDA-MB-231, but it significantly inhibited the growth of human gastric cancer SGC-7901 cells, caused cell apoptosis and cell cycle arrest in S phase, with increased production of reactive oxygen species (ROS) and reduced mitochondrial membrane potential (MMP). The results indicate that Chinese propolis sourced from the Changbai Mountains selectively inhibits the proliferation of human gastric cancer SGC-7901 cells by inducing both death receptor-induced apoptosis and mitochondria-mediated apoptosis, and cell cycle arrest in S phase. These activities and mechanisms help understand the anticancer action of propolis and its active compounds.

Development and application of an UHPLC-MS method for comparative pharmacokinetic study of phenolic components from dragon's blood in rats under simulated microgravity environment.

Dragon's blood is a commonly used Chinese herbal medicine shown to have protective effects in simulated microgravity in rats and mice. The current study aimed to develop an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS) method for simultaneous determination of four phenolic components from the herb: loureirin A, loureirin C, 7,4'-dihydroxyflavone and pterostilbene in rats, and use the method for comparative study on the pharmacokinetics (PK) and excretion of these components in rats after oral dosage of dragon's blood under simulated microgravity environments. The results showed the developed UHPLC-MS method was sensitive and rapid. The comparative pharmacokinetic study in rats showed loureirin A, loureirin C and 7,4-dihydroxyflavone had decreased Cmax and AUC and increased Vd and CL in simulated microgravity environment; but pterostilbene had the opposite changes. The four phenolic components also showed increased or decreased excretions in simulated microgravity rats. These results indicate the chemical structure and physicochemical property, as well as physiological conditions may have an impact on the absorption and excretion of phenolic components in simulated microgravity environment. It also implies that different drug may behave differently in the same spaceflight condition leading to an increase or a reduction in pharmacodynamic outcomes.

Seasonal Variation of Triterpenes and Phenolic Compounds in Australian Centella asiatica (L.) Urb.

INTRODUCTION: Specific triterpenes, phenolic acids and flavonoids in Centella asiatica have been found to be bioactive. Harvesting the plant when these putative bioactive compounds are at their highest concentrations would provide consistency in their chemical profile, thus ensuring the quality and efficacy of derived medicinal products. OBJECTIVE: The aim of the study was to determine the impact of harvesting time on the contents of major triterpenoid and phenolic compounds in C. asiatica. METHODOLOGY: Australian C. asiatica was collected from a designated area in different months. The principal triterpenes (asiaticoside, madecassoside, asiatic acid and madecassic acid), flavonoid compounds (rutin, quercetin and kaempferol) and chlorogenic acid were quantitatively determined by HPLC-DAD analysis. RESULTS: Triterpenoid, kaempferol and chlorogenic acid content showed significant variation (p < 0.05) in different collecting months. The total content of the four triterpenes reached its highest levels in January and February (83.15 ± 0.16 mg/g and 78.41 ± 0.16 mg/g, respectively), the summer season of the southern hemisphere, and their lowest values in winter (June) and spring (October) seasons (35.65 ± 0.20 and 35.50 ± 0.55 mg/g, respectively). Similarly, the contents of chlorogenic acid and kaempferol were the highest in December and January (1.62 ± 0.01 and 0.33 ± 0.01 mg/g, respectively), and the lowest in June (0.06 ± 0.01 and 0.09 ± 0.01 mg/g, respectively). CONCLUSION: The results indicate that harvesting C. asiatica in summer returns the highest yield of the target triterpenoids, kaempferol and chlorogenic acid.

Tetracyclic triterpenoids in herbal medicines and their activities in diabetes and its complications.

Tetracyclic triterpenoids, including the dammarane, cucurbitane, cycloartane, lanostane and protostane groups, is a class of triterpenoids widely distributed in various medicinal plants, particularly those commonly used for the treatment of diabetes and its complications, such as Panax ginseng, Panax quinquefolium, Panax notoginseng, Gynostemma pentaphyllum, Astragalus membranaceus, Momordica charantia, and Ganoderma lucidum. This review highlights recent findings on the chemistry and bioactivities of tetracyclic triterpenoids from these plants and other popular herbal medicines.

Comparing morphological, chemical and anti-diabetic characteristics of Puerariae Lobatae Radix and Puerariae Thomsonii Radix.

ETHNOPHARMACOLOGICAL RELEVANCE: Puerariae Lobatae Radix (PLR) and Puerariae Thomsonii Radix (PTR) are traditional Chinese medicines used for the treatment of diabetes and cardiovascular diseases. These two herbs are used interchangeably in clinical practice, even though they possess significantly different chemical profiles. In the case of Pueraria species, the misidentification is related to the multiple Chinese common names in clinical practice and variable pharmaceutical Latin names in different versions of the Pharmacopoeia of the People's Republic of China. In addition, there is lack of evidence demonstrating how the differences in the chemical profile would impact on the pharmacological activity of the two herbs. Therefore, the aim of this study was to compare the microscopic, phytochemical profiles and anti-diabetic activity of PLR and PTR so that the two species can be differentiated. MATERIALS AND METHODS: The microscopic characteristics of the PLR and PTR were observed and measured by an optical microscope. The major compounds were quantified by ultra-performance liquid chromatography (UPLC) and total flavonoid content (TFC) colorimetric assay. The free radical scavenging capacity was assessed by 2,2-diphenyl-2-picrylhydrazyl (DPPH) antioxidant assays. Anti-diabetic activity was determined by the inhibition of porcine pancreatic α-amylase and rat intestinal α-glucosidase activities. RESULTS: Microscopic results illustrated that the size of xylem vessels (PLR: 0.1390 ± 0.0184 mm; PTR: 0.0471 ± 0.0109 mm), number of fibre per bundle (PLR: 32.6800 ± 2.8780; PTR: 16.5900 ± 0.9982) and the size of fibre (PLR: 0.0075 ± 0.0003 mm(2); PTR: 0.0025 ± 0.0002 mm(2)) in PLR were significantly greater than that in PTR (p<0.01). PLR possessed a significantly lower total starch content (PLR: 0.5288 ± 1.2559 mg starch/g DM; PTR: 76.7954 ± 2.9905 mg starch/g DM) and total dietary fibre content (PLR: 4.2886 ± 0.3466 g/100g DM; PTR: 12.4148 ± 0.4541 g/100g DM) as compared to PTR. Isoflavonoids including puerarin, daidzin, genistin and daidzein were the major chemical constituents in both species. However, the average content of puerarin in PLR was found to be eleven times greater than that in PTR. Furthermore, the TFC, DPPH free radical scavenging capacity, anti-α-amylase and anti-α-glucosidase in the PLR extracts were 4.42, 4.91, 3.10 and 4.22 times greater than in the PTR extracts. CONCLUSIONS: This study provides a comprehensive investigation on the two medicinal valuable Pueraria species and allows differences to be ascertained. This information can be used to update monographs which will help practitioners and dispensers differentiate the herbs. Further study on the interchangeable use of PLR and PTR in clinical practice is urgently warranted.

Identification of catechol as a new marker for detecting propolis adulteration.

Adulteration of propolis with poplar extract is a serious issue in the bee products market. The aim of this study was to identify marker compounds in adulterated propolis, and examine the transformation of chemical components from poplar buds to propolis. The chemical profiles of poplar extracts and propolis were compared, and a new marker compound, catechol, was isolated and identified from the extracts of poplar buds. The polyphenol oxidase, catechol oxidase, responsible for catalyzing oxidation of catechol was detected in poplar buds and propolis. The results indicate catechol can be used as a marker to detect propolis adulterated with poplar extract.

Differentiating Puerariae Lobatae Radix and Puerariae Thomsonii Radix using HPTLC coupled with multivariate classification analyses.

Puerariae Lobatae Radix (PLR), the root of Pueraria lobata, is a traditional Chinese medicine for treating diabetes and cardiovascular diseases. Puerariae Thomsonii Radix (PTR), the root of Pueraria thomsonii, is a closely related species to PLR and has been used as a PLR substitute in clinical practice. The aim of this study was to compare the classification accuracy of high performance thin-layer chromatography (HPTLC) with that of ultra-performance liquid chromatography (UPLC) in differentiating PLR from PTR. The Matlab functions were used to facilitate the digitalisation and pre-processing of the HPTLC plates. Seven multivariate classification methods were evaluated for the two chromatographic methods. The results demonstrated that the HPTLC classification models were comparable to the UPLC classification models. In particular, k-nearest neighbours, partial least square-discriminant analysis, principal component analysis-discriminant analysis and support vector machine-discriminant analysis showed the highest rate of correct species classification, whilst the lowest classification rate was obtained from soft independent modelling of class analogy. In conclusion, HPTLC combined with multivariate analysis is a promising technique for the quality control and differentiation of PLR and PTR.

Pharmacokinetics of plantamajoside and acteoside from Plantago asiatica in rats by liquid chromatography-mass spectrometry.

Plantago asiatica is a medicinal and dietary plant rich in polyphenolic compounds such as phenylpropanoid glycosides plantamajoside and acteoside. The aims of the present study were to develop a new and sensitive method for simultaneous determination of plantamajoside and acteoside and investigate their pharmacokinetic properties in rats. A sensitive and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with multiple-reaction monitoring (MRM) mode was employed for quantification of two analytes in rat plasma. The calibration curve was linear over the range of 0.2-200ng/ml with correlation coefficient greater than 0.9983 for both analytes. The accuracy of plantamajoside and acteoside were between -4.2% and 8.1%, -3.8% and 8.9% relative error, respectively. Precision for the two analytes ranged from 2.7 to 10.2% relative standard deviation. The pharmacokinetic results showed plantamajoside and acteoside were quickly absorbed in rat with the time to maximum plasma concentration 16.7±2.8 and 13.3±2.8min, respectively. The elimination constants were 0.28±0.01 1h(-1) for plantamajoside and 0.47±0.03 1h(-1) for acteoside. The developed method and the pharmacokinetic data provide a basis for further studies on bioactivity of P. asiatica.

Herbal medicines for fatty liver diseases.

BACKGROUND: Fatty liver disease is potentially a reversible condition that may lead to end-stage liver disease. Since herbal medicines such as Crataegus pinnatifida and Salvia miltiorrhiza have increasingly been used in the management of fatty liver disease, a systematic review on herbal medicine for fatty liver disease is needed. OBJECTIVES: To assess the beneficial and harmful effects of herbal medicines for people with alcoholic or non-alcoholic fatty liver disease. SEARCH METHODS: We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 3, 2012), MEDLINE, EMBASE, and Science Citation Index Expanded to 1 March 2012. We also searched the Chinese BioMedical Database, Traditional Chinese Medical Literature Analysis and Retrieval System, China National Knowledge Infrastructure, Chinese VIP Information, Chinese Academic Conference Papers Database and Chinese Dissertation Database, and the Allied and Complementary Medicine Database to 2 March 2012. SELECTION CRITERIA: We included randomised clinical trials comparing herbal medicines with placebo, no treatment, a pharmacological intervention, or a non-pharmacological intervention such as diet or lifestyle, or Western interventions in participants with fatty liver disease. DATA COLLECTION AND ANALYSIS: Two review authors extracted data independently. We used the 'risk of bias' tool to assess the risk of bias of the included trials. We assessed the following domains: random sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting, and other sources of bias. We presented the effects estimates as risk ratios (RR) with 95% confidence intervals (CI) or as mean differences (MD) with 95% CI, depending on the variables of the outcome measures. MAIN RESULTS: We included 77 randomised clinical trials, which included 6753 participants with fatty liver disease. The risks of bias (overestimation of benefits and underestimation of harms) was high in all trials. The mean sample size was 88 participants (ranging from 40 to 200 participants) per trial. Seventy-five different herbal medicine products were tested. Herbal medicines tested in the randomised trials included single-herb products (Gynostemma pentaphyllum, Panax notoginseng, and Prunus armeniaca), proprietary herbal medicines commercially available, and combination formulas prescribed by practitioners. The most commonly used herbs were Crataegus pinnatifida,Salvia miltiorrhiza,Alisma orientalis,Bupleurum Chinense,Cassia obtusifolia, Astragalus membranaceous, and Rheum palmatum. None of the trials reported death, hepatic-related morbidity, quality of life, or costs. A large number of trials reported positive effects on putative surrogate outcomes such as serum aspartate aminotransferase, alanine aminotransferase, glutamyltransferase, alkaline phosphatases, ultrasound, and computed tomography scan. Twenty-seven trials reported adverse effects and found no significant difference between herbal medicines versus control. However, the risk of bias of the included trials was high.The outcomes were ultrasound findings in 22 trials, liver computed tomography findings in eight trials, aspartate aminotransferase levels in 64 trials, alanine aminotransferase activity in 77 trials, and glutamyltransferase activities in 44 trials. Six herbal medicines showed statistically significant beneficial effects on ultrasound, four on liver computed tomography, 42 on aspartate aminotransferase activity, 49 on alanine aminotransferase activity, three on alkaline phosphatases activity, and 32 on glutamyltransferase activity compared with control interventions. AUTHORS' CONCLUSIONS: Some herbal medicines seemed to have positive effects on aspartate aminotransferase, alanine aminotransferase, ultrasound, and computed tomography. We found no significant difference on adverse effects between herbal medicine and control groups. The findings are not conclusive due to the high risk of bias of the included trials and the limited number of trials testing individual herbal medicines. Accordingly, there is also high risk of random errors.

Differentiation of Pueraria lobata and Pueraria thomsonii using partial least square discriminant analysis (PLS-DA).

The aims of the study were to differentiate Pueraria lobata from its related species Pueraria thomsonii and to examine the raw herbal material used in manufacturing kudzu root granules using partial least square discriminant analysis (PLS-DA). Sixty-four raw materials of P. lobata and P. thomsonii and kudzu root-labelled granules were analysed by ultra performance liquid chromatography. To differentiate P. lobata from P. thomsonii, PLS-DA models using the variables selected from the entire chromatograms, genetic algorithm (GA), successive projection algorithm (SPA), puerarin alone and six selected peaks were employed. The models constructed by GA and SPA demonstrated superior classification ability and lower model's complexity as compared to the model based on the entire chromatographic matrix, whilst the model constructed by the six selected peaks was comparable to the entire chromatographic model. The model established by puerarin alone showed inferior classification ability. In addition, the PLS-DA models constructed by the entire chromatographic matrix, GA, SPA and the six selected peaks showed that four brands out of seventeen granules were mislabelled as P. lobata. In conclusion, PLS-DA is a promising procedure for differentiating Pueraria species and determining raw material used in commercial products.

Chinese herbal medicines for hypertriglyceridaemia.

BACKGROUND: Hypertriglyceridaemia is associated with many diseases including atherosclerosis, diabetes, hypertension and chylomicronaemia. Chinese herbal medicines have been used for a long time as lipid-lowering agents. OBJECTIVES: To assess the effects and safety of Chinese herbal medicines for hypertriglyceridaemia. SEARCH METHODS: We searched a number of databases including The Cochrane Library, MEDLINE, EMBASE and several Chinese databases (all until May 2012). SELECTION CRITERIA: Randomised controlled trials in participants with hypertriglyceridaemia comparing Chinese herbal medicines with placebo, no treatment, and pharmacological or non-pharmacological interventions. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed the risk of bias. Any disagreement was resolved by discussion and a decision was achieved based on consensus. We assessed trials for risk of bias against key criteria: random sequence generation, allocation concealment, blinding of participants, incomplete outcome data, selective outcome reporting and other sources of bias. MAIN RESULTS: We included three randomised trials with 170 participants. Ninety participants were randomised to the Chinese herbal medicines groups and 80 to the comparator groups with numbers ranging from 50 to 60 participants per trial. The duration of treatment varied from four to six weeks. All the included trials were conducted in China and published in Chinese. Overall, the risk of bias of included trials was unclear. There were no outcome data in any of the trials on death from any cause, cardiovascular or cerebrovascular events, health-related quality of life, or costs.Three different herbal medicines, including Zhusuan Huoxue decoction, Huoxue Huayu Tongluo decoction, and Chushi Huayu decoction were evaluated. All three trials investigating Chinese herbal medicines treatment alone (two studies) or in combination with gemfibrozil (one study) reported results on serum triglyceride (TG) in favour of the herbal treatment. We did not perform a meta-analysis due to significant clinical heterogeneity between the studies.No relevant differences in adverse effects occurred and no serious adverse events were noted. AUTHORS' CONCLUSIONS: The present systematic review suggests that Chinese herbal medicines may have positive effects on hypertriglyceridaemia. The trials did not report serious adverse effects following Chinese herbal medicines treatment. However, based on an unclear risk of bias in included studies and lack of patient-important long-term outcomes, no definite conclusion could be reached.

Evidence-based toxicity evaluation and scheduling of Chinese herbal medicines.

ETHNOPHARMACOLOGICAL RELEVANCE: While there is an increasing number of toxicity report cases and toxicological studies on Chinese herbal medicines, the guidelines for toxicity evaluation and scheduling of Chinese herbal medicines are lacking. AIM: The aim of this study was to review the current literature on potentially toxic Chinese herbal medicines, and to develop a scheduling platform which will inform an evidence-based regulatory framework for these medicines in the community. MATERIALS AND METHODS: The Australian and Chinese regulations were used as a starting point to compile a list of potentially toxic herbs. Systematic literature searches of botanical and pharmaceutical Latin name, English and Chinese names and suspected toxic chemicals were conducted on Medline, PubMed and Chinese CNKI databases. RESULTS: Seventy-four Chinese herbal medicines were identified and five of them were selected for detailed study. Preclinical and clinical data were summarised at six levels. Based on the evaluation criteria, which included risk-benefit analysis, severity of toxic effects and clinical and preclinical data, four regulatory classes were proposed: Prohibited for medicinal usage, which are those with high toxicity and can lead to injury or death, e.g., aristolochia; Restricted for medicinal usage, e.g., aconite, asarum, and ephedra; Required warning label, e.g., coltsfoot; and Over-the-counter herbs for those herbs with a safe toxicity profile. CONCLUSION: Chinese herbal medicines should be scheduled based on a set of evaluation criteria, to ensure their safe use and to satisfy the need for access to the herbs. The current Chinese and Australian regulation of Chinese herbal medicines should be updated to restrict the access of some potentially toxic herbs to Chinese medicine practitioners who are qualified through registration.

A comparative study on the inhibitory effects of different parts and chemical constituents of pomegranate on α-amylase and α-glucosidase.

Pomegranate has been documented for the management of diabetes in Unani and Chinese medicine. This study compared the effects of the extracts of different pomegranate parts, including juice, peels, seeds and flowers, on carbohydrate digestive enzymes (α-amylase and α-glucosidase) in vitro. The methanolic flower extract inhibited α-amylase and α-glucosidase, while the methanolic peel extract inhibited α-glucosidase selectively. The most active flower extract was subjected to water-ethyl acetate partition. The ethyl acetate fraction was more potent than the water fraction in inhibiting both enzymes. Gallic acid and ellagic acid also showed selective inhibition against α-glucosidase, and their presence in the ethyl acetate fraction was confirmed by HPLC-DAD and HPLC-HESI-MS. Our findings suggest that the inhibition of carbohydrate digestive enzymes and their phenolic content may contribute to the anti-hyperglycaemic effects of pomegranate flower and peel, and support their claims in diabetes.

Influences of processed rhubarbs on the activities of four CYP isozymes and the metabolism of saxagliptin in rats based on probe cocktail and pharmacokinetics approaches.

ETHNOPHARMACOLOGICAL RELEVANCE: Cooked rhubarb and wine processed rhubarb are the processed rhubarbs of raw rhizomes from Rheum palmatum L., Rheum tanguticum Maxim. ex Balf. or Rheum officinale Baill. They are clinically used in traditional Chinese medicine to compose anti-diabetic formulas and remove pathogenic heat or toxin from the body. AIM OF THE STUDY: To elucidate potential influences processed rhubarbs might have on the activities of four cytochrome P450 (CYP) isozyme in rats (CYP1A2, CYP2C6, CYP2E1, and CYP3A1) and on the pharmacokinetics of saxagliptin. MATERIALS AND METHODS: Relative activity estimation of four isozymes or influence on saxagliptin was carried out by comparing plasma pharmacokinetics of four respective substrates (theophylline for CYP1A2, tolbutamide for CYP2C6, chlorzoxazone for CYP2E1, and dapsone for CYP3A1) or saxagliptin between control and processed rhubarbs pretreated groups. Plasma concentrations of substrates and saxagliptin were quantified using UPLC-UV and UPLC-MS/MS methods, respectively. RESULTS: Wine processed rhubarb induced CYP1A2 activity; both the processed rhubarbs inhibited the CYP2C6 activity and induced CYP2E1; cooked rhubarb induced CYP3A1 activity. Both the processed rhubarbs reduced the absorbance and bioavailability, but increased the clearance of saxagliptin. CONCLUSIONS: Processed rhubarbs can either induce or inhibit activities of CYP1A2, CYP2C6, CYP2E1, and CYP3A1, and modify the metabolism of saxagliptin. The results indicated that drug co-administrated with processed rhubarbs may need dose adjustment.

Quantifying four-probe metabolites in a single UPLC-MS/MS run to explore the effects of cooked rhubarb on cytochrome P450 isozymes.

BACKGROUND: Cytochrome P450 (CYP) enzymes primarily account for the oxidation of xenobiotics. A single run UPLC-MS/MS method was developed to simultaneously detect four metabolites from a probe cocktail to investigate four CYP isozymes. Paracetamol was detected to investigate CYP1A2, 4-hydroxytolbutamide for CYP2C6, 6-hydroxychlorzoxazone for CYP2E1 and dehydronifedipine for CYP3A1. 6-hydroxychlorzoxazone was detected in ESI-negative mode, while the other three were detected in ESI-positive mode. RESULTS: The method was rapid (2.5 min) and validated to be specific, accurate and precise. It was successfully applied to evaluate the effects of cooked rhubarb on the activities of the four isozymes in rat microsomes. Cooked rhubarb inhibited the activity of CYP2C6 but induced both CYP2E1 and CYP3A1. CONCLUSION: This convenient UPLC-MS/MS method was applicable. It could improve the efficiency of future studies estimating the influence of herbs, herbal products or drug entities on the activities of CYP1A2, CYP2C6, CYP2E1 and CYP3A1.

Herbal medicines for the management of diabetes.

Herbal medicines have been used in the management of diabetes in traditional medicine. This chapter reviews recent findings of the most popular herbs reported to treat diabetes through their relevant mechanistic pathways. These include increased insulin secretion, improvement in insulin sensitivity, enhanced glucose uptake by adipose and muscle tissues, inhibition of glucose absorption from intestine, inhibition of glucose production from hepatocytes and anti-inflammatory activities. The pharmacological activities have highlighted the potential efficacy of these herbal medicines in the management of diabetes.

Kudzu root: traditional uses and potential medicinal benefits in diabetes and cardiovascular diseases.

Kudzu root (Gegen in Chinese) is the dried root of Pueraria lobata (Willd.) Ohwi, a semi-woody, perennial and leguminous vine native to South East Asia. It is often used interchangeably in traditional Chinese medicine with thomson kudzu root (Fengen in Chinese), the dried root of P. thomsonii, although the Chinese Pharmacopoeia has separated them into two monographs since the 2005 edition. For more than 2000 years, kudzu root has been used as a herbal medicine for the treatment of fever, acute dysentery, diarrhoea, diabetes and cardiovascular diseases. Both English and Chinese literatures on the traditional applications, phytochemistry, pharmacological activities, toxicology, quality control and potential interactions with conventional drugs of both species have been included in the present review. Over seventy phytochemicals have been identified in kudzu root, with isoflavonoids and triterpenoids as the major constituents. Isoflavonoids, in particular puerarin, have been used in most of the pharmacological studies. Animal and cellular studies have provided support for the traditional uses of kudzu root on cardiovascular, cerebrovascular and endocrine systems, including diabetes and its complications. Further studies to define the active phytochemical compositions, quality standards and clinical efficacy are warranted. Strong interdisciplinary collaboration to bridge the gap between traditional medicine and modern biomedical medicine is therefore needed for the development of kudzu root as an effective medicine for the management of diabetes and cardiovascular diseases.

Herbal medicines and nutraceuticals for diabetic vascular complications: mechanisms of action and bioactive phytochemicals.

Diabetes is one of the most prevalent chronic diseases throughout the world. The majority of its complications arise from vascular-related inflammation apparently initiated by endothelial cell injury. One cause of this injury has been attributed to hyperglycaemia-induced reactive oxygen species. Consequently, current drug developmental strategy has targeted specific inflammatory and oxidative stress pathways for the prevention of diabetic vascular complications. Herbal medicines have traditionally been used for the treatment of diabetes and its complications. In fact, current pre-clinical and clinical studies have demonstrated that many of them exhibit potent anti-inflammatory and anti-oxidative properties, and have also identified the active phytochemicals responsible for their activities. The present review summarises the latest research on the molecular mechanisms of diabetic vascular complications, and evaluates the level of scientific evidence for common herbal medicines and their bioactive phytochemicals. These agents have been shown to be effective through various mechanisms, particularly the NF-κB signalling pathways. Overall, herbal medicines and nutraceuticals, as well as their bioactive components, which exhibit anti-inflammatory and anti-oxidative properties, provide a promising approach for the prevention and treatment of diabetic complications.

Quantitative analysis of two isoflavones in Pueraria lobata flowers from eleven Chinese provinces using high performance liquid chromatography.

BACKGROUND: Pueraria lobata flower (Gehua) is a medicinal herb to treat intoxication, hepatic and gastrointestinal tract lesion induced by alcohol. This study aims to develop a new HPLC method for the determination of two major isoflavones in P. lobata flowers, namely tectoridin and 6"-O-xylosyl-tectoridin. METHODS: A high performance liquid chromatography (HPLC) method with a C18 column (250 mm x 4.6 mm, 5 mum) was developed for the quantitative analysis of tectoridin and 6"-O-xylosyl-tectoridin, the main isoflavone components in P. lobata flower. A simple gradient of acetonitrile/water (0 min 15:85; 35 min 50:50; 36 min 15:85; 40 min 15:85; v/v) was used, and 265 nm was selected as detection wavelength. Tectoridin and 6"-O-xylosyl-tectoridin were used as the external standards in quality control of P. lobata flower for the first time. The method was applied to practical use in quality assessment of eleven batches of P. lobata flower samples in Chinese herbal medicine market. RESULTS: The peak area response was linear for tectoridin in the 11.8-236.4 mug/mL range with a correlation coefficient of 0.9996 (P < 0.001), and for 6"-O-xylosyl-tectoridin in the 10.33-185.99 mug/mL range with a correlation coefficient of 0.9984 (P < 0.001) respectively. The average recoveries were 102.7-103.7% for tectoridin and 95.7-103.2% for 6"-O-xylosyl-tectoridin (RSDs < 3%), and the intra-day and inter-day RSDs of the two components were less than 2%. This HPLC method was applied to assess the quality of P. lobata flower from eleven provinces in China. P. lobata flowers from northern China contained 26.46-43.28 mg/g of tectoridin and 30.90-48.23 mg/g of 6"-O-xylosyl-tectoridin comparing to 10.00-19.81 mg/g of tectoridin and 11.08-37.03 mg/g of 6"-O-xylosyl-tectoridin in those from southern China. CONCLUSION: The results showed that P. lobata flowers from northern China contained more tectoridin and 6"-O-xylosyl-tectoridin than those from southern China.