Hepatobiliary excretion of berberine

Berberine and Its Role in Chronic Disease

Berberine is a quaternary ammonium salt from the protoberberine group of isoquinoline alkaloids. It is found in such plants as Berberis [e.g. Berberis aquifolium (Oregon grape), Berberis vulgaris (barberry), Berberis aristata (tree turmeric)], Hydrastis canadensis (goldenseal), Xanthorhiza simplicissima (yellowroot), Phellodendron amurense ^[2] (Amur corktree), Coptis chinensis (Chinese goldthread), Tinospora cordifolia, Argemone mexicana (prickly poppy) and Eschscholzia californica (Californian poppy). In vitro it exerts significant anti-inflammatory and antioxidant activities. In animal models berberine has neuroprotective and cardiovascular protective effects. In humans, its lipid-lowering and insulin-resistance improving actions have clearly been demonstrated in numerous randomized clinical trials. Moreover, preliminary clinical evidence suggest the ability of berberine to reduce endothelial inflammation improving vascular health, even in patients already affected by cardiovascular diseases. Altogether the available evidences suggest a possible application of berberine use in the management of chronic cardiometabolic disorders.

Study progress of berberine for treating cardiovascular disease

Berberine (BBR) is a natural alkaloid isolated from the Coptis chinensis. While this plant has been used in Chinese medicine for more than 2500 years, interest in its effects in treating cardiovascular disease has been growing in the last decade. Recent researches showed that BBR had the effect of anti-heart failure, anti-hypertension, anti-hyperlipidemia, anti-insulin resistance, anti-arrhythmias, and anti-platelet aggregation.

Validated UPLC-MS/MS method for simultaneous determination of simvastatin, simvastatin hydroxy acid and berberine in rat plasma: Application to the drug-drug pharmacokinetic interaction study of simvastatin combined with berberine after oral administration in rats

A rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method was developed and validated for simultaneous quantification of simvastatin (SV), its metabolite simvastatin hydroxy acid (SVA) and berberine (BBR) in rat plasma. Separation was performed on Poroshell 120 EC-C18 column (4.6×50mm, 2.7μm) using gradient elution by mobile phase containing acetonitrile and 10mM ammonium acetate (pH 4.5). Polarity switch (positive-negative-positive ionization mode) was performed in a total run time of 4.0min. The lower limits of quantification (LLOQ) for SV, SVA and BBR were 0.10, 0.20 and 0.10ng/mL, respectively. The response function was established for concentration range of 0.10-100ng/mL for SV and BBR and 0.20-3000ng/mL for SVA, with a coefficient of correlation of >0.99 for all the compounds. The proposed method was applied to the drug-drug pharmacokinetic interaction study of SV combined with BBR after oral administration in rats.

Berberine-loaded solid lipid nanoparticles are concentrated in the liver and ameliorate hepatosteatosis in db/db mice

Berberine (BBR) shows very low plasma levels after oral administration due to its poor absorption by the gastrointestinal tract. We have previously demonstrated that BBR showed increased gastrointestinal absorption and enhanced antidiabetic effects in db/db mice after being entrapped into solid lipid nanoparticles (SLNs). However, whether BBR-loaded SLNs (BBR-SLNs) also have beneficial effects on hepatosteatosis is not clear. We investigated the effects of BBR-SLNs on lipid metabolism in the liver using histological staining and reverse transcription polymerase chain reaction analysis. The results showed that oral administration of BBR-SLNs inhibited the increase of body weight and decreased liver weight in parallel with the reduction of serum alanine transaminase and liver triglyceride levels in db/db mice. The maximum drug concentration in the liver was 20-fold higher than that in the blood. BBR-SLNs reduced fat accumulation and lipid droplet sizes significantly in the liver, as indicated by hematoxylin and eosin and Oil Red O staining. The expression of lipogenic genes, including fatty acid synthase (FAS), stearoyl-CoA desaturase (SCD1), and sterol regulatory element-binding protein 1c (SREBP1c) were downregulated, while lipolytic gene carnitine palmitoyltransferase-1 (CPT1) was upregulated in BBR-SLN-treated livers. In summary, we have uncovered an unexpected effect of BBR-SLNs on hepatosteatosis treatment through the inhibition of lipogenesis and the induction of lipolysis in the liver of db/db mice.

Pharmacokinetics and Brain Distribution and Metabolite Identification of Coptisine, a Protoberberine Alkaloid with Therapeutic Potential for CNS Disorders, in Rats

Coptisine (COP), a protoberberine alkaloid (PBA) from Chinese medicinal plants (such as family Berberidaceae), may be useful for improving central nervous system disorders. However, its pharmacokinetics, disposition and metabolism are not well defined. In the present study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established for the analysis of COP in biological samples. To better understand its in vivo pharmacological activities, COP concentrations in rat plasma were determined after oral (50 mg/kg) and intravenous administration (10 mg/kg). For the brain distribution study, the concentration of COP in five different regions was examined after intravenous administration at 10 mg/kg. Pharmacokinetic parameters from the COP concentration-time profiles in plasma and brain, and the brain-to-plasma coefficient (Kp, brain) were calculated by non-compartmental analysis. The metabolites of COP in rats in vivo and in vitro (urine, bile, liver microsomes and intestinal bacteria incubation) were also identified. Seventeen metabolites, including 11 unconjugated metabolites formed by hydroxylation, hydrogenation, demethylation, dehydrogenation, demethylation, and 6 glucuronide and sulfate conjugates were identified for the first time. The results suggested that COP had low oral bioavailability of 8.9% and a short (plasma) half-life (T1/2=0.71 h) in rats. After intravenous administration, it quickly crossed the blood-brain barrier, accumulating at higher concentrations and then was slowly eliminated from different brain regions. Moreover, COP was transformed into metabolites through multiple metabolic pathways in vivo and in vitro. These results should help to promote further research on COP and contribute to clarifying the metabolic pathways of PBAs.

Clinical role of a fixed combination of standardized Berberis aristata and Silybum marianum extracts in diabetic and hypercholesterolemic patients intolerant to statins

BACKGROUND

Statin intolerance is a medical condition often leading patients to nonadherence to the prescribed therapy or to a relevant reduction of the statin dosage. Both situations determine a totally or partially uncontrolled lipid profile, and these conditions unquestionably increase the risk of cardiovascular events.

METHODS

We enrolled hypercholesterolemic, type 2 diabetic patients complaining of intolerance to statins. Some of them had reduced the statin dose 'until the disappearance of symptoms'; others had opted for treatment with ezetimibe; and yet others were not undergoing any treatment at all. All patients of the three groups were then given a fixed combination of berberine and silymarin (Berberol(®)), known from previous papers to be able to control both lipidic and glycemic profiles.

RESULTS

The tested product both as a single therapy and as add-on therapy to low-dose statin or to ezetimibe reduced triglycerides, low-density lipoprotein cholesterol, fasting blood glucose, and glycosylated hemoglobin in a significant manner without inducing toxicity conditions that might be somehow ascribed to a statin-intolerant condition.

CONCLUSION

Our study demonstrates that use of Berberol(®), administered as a single or add-on therapy in statin-intolerant subjects affected by diabetes and hypercholesterolemia is a safe and effective tool capable of improving the patients' lipidic and glycemic profiles.

In vitro studies of berberine metabolism and its effect of enzyme induction on HepG2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Berberine (BER) and BER-original herbal medicines have a variety of pharmacological functions and have been widely used in clinical. However, its effect of enzyme induction on cytochrome P450 (CYP) in human hepatocytes is unknown.

MATERIAL AND METHOD

Metabolism of berberine and its effect on main metabolic enzymes in HepG2 cell in vitro was investigated. Cocktail probe drugs, mRNA expression and protein expression were used to evaluate the metabolism potency. Meanwhile, an UPLC-MS/MS method was validated for the analysis of BER and four probe drugs in HepG2 cell.

RESULT

BER significantly increased the metabolism of midazolam, phenacetin and tolbutamide by inducing the CYP1A2 and 3A4 enzyme in a dose-dependent manner, the mRNA and protein expression of CYP1A2 and 3A4 were increased by berberine at 1000ng·mL(-1). The activity of CYP1A2 and 3A4 could be induced by BER more than 500ng·mL(-1) in HepG2 cell, which was confirmed by the increase of its mRNA and protein expression.

CONCLUSION

BER increases the metabolism of cocktail drugs such as midazolam, phenacetin and tolbutamide by increasing the mRNA and protein expression of CYP1A2 and 3A4.

LC-MS/MS determination and pharmacokinetic study of dehydrocorydaline in rat plasma after oral administration of dehydrocorydaline and Corydalis yanhusuo extract

A rapid, sensitive and selective liquid chromatography/tandem mass spectrometry method (LC-MS/MS) was developed and validated for determination of dehydrocorydaline (DHC) in rat plasma using nitidine chloride as an internal standard. The analytes were solid-phase extracted and eluted on a C18 chromatography column using a mobile phase of acetonitrile and water (containing 0.8% formic acid and 10 mM ammonium acetate) (28:72, v/v). Detection was performed using positive ion electrospray ionization in multiple reaction monitoring modes. The assay was linear over the concentration range 0.625-250 ng/mL with a quantification limit of 0.625 ng/mL. The precision was <13.7%, the accuracy >93.1%, and extraction recovery ranged from 92.1% to 107%. The validated method was successfully applied to the pharmacokinetics and excretion study of DHC in rat plasma after oral administration of pure DHC and an effective fraction of Corydalis yanhusuo (EFY). The pharmacokinetic parameters showed that DHC from EFY was absorbed more rapidly and eliminated more slowly than pure DHC. The result suggests that the differences might be due to the presence of P-glycoprotein (P-gp) inhibitors and that other alkaloids co-existing in the EFY may compete with DHC for transportation by P-gp, metabolization by P450, and binding to plasma proteins.

Cyclosporine and herbal supplement interactions

Cyclosporine (CyA) is a well-known immunosuppressant with a narrow therapeutic window. Its bioavailability is affected by many other traditional drugs and herbal extracts. Cytochrome P-450 isoenzymes CYP3A4 and CYP3A5 and protein P-glycoprotein (P-gp) are involved in CyA bioavailability. Interactions of CyA with herbal extracts are not well known, but, given their increased concomitant use, it is important to know which extracts, many of which are commonly self-prescribed, can affect CyA blood concentrations. Decreased CyA blood concentration has been shown with St John's wort in case reports and, in vivo animal studies, with ginger, liquorice, scutellariae radix, and quercetin. Increased CyA concentration has been reported in patients with grapefruit juice, chamomile, or berberine, and with cannabidiol or resveratrol in animal studies. Effects of Echinacea and Serenoa repens on CyA levels have not been shown consistently, but concomitant use should be avoided. Although findings from animal studies cannot be directly translated into humans, avoiding concomitant use of herbal extracts is prudent until human clinical studies have ruled out any possible interaction. Clinicians should interview their patients carefully about their use of herbal supplements before CyA administration, and those receiving CyA should be warned about possible interactions between herbal preparations and CyA.

Berberine metabolites could induce low density lipoprotein receptor up-regulation to exert lipid-lowering effects in human hepatoma cells

Berberine (BBR) is an isoquinoline alkaloid isolated from several Chinese herbal medicines, such as Coptis chinensis, Berberis aristata, and Coptis japonica. It exhibits a lipid-lowering effect by up-regulating the hepatic low density lipoprotein receptor (LDLR) expression. However, the plasma concentration of BBR is very low after oral administration for the reason that BBR is poorly absorbed and rapidly metabolized. Therefore, it is hard to explain the pharmacological effects of BBR in vivo. Here, RT-PCR, Western blotting and Oil Red O staining were used to investigate the effects of four BBR metabolites on LDLR expression and lipid accumulation in human hepatoma Hep G2 cells. Our results suggested that BBR increased the LDLR mRNA and protein levels in a time- and dose-dependent manner. Four metabolites of BBR, jatrorrhizine, columbamine, berberrubine and demethyleneberberine, were found to be able to up-regulate LDLR mRNA and protein expression. Moreover, almost all the metabolites had potent effects on inhibiting cellular lipid accumulation. These results suggest that both BBR and its metabolites exhibit lipid-lowering effects by up-regulating LDLR expression, and BBR and its metabolites might be the in vivo active forms of BBR produced after oral administration. This study provides information to help us understand the mechanisms underlying the hypolipidemic effects of BBR in vivo.

Preliminary study about the possible glycemic clinical advantage in using a fixed combination of Berberis aristata and Silybum marianum standardized extracts versus only Berberis aristata in patients with type 2 diabetes

Background

Berberine is an isoquinoline alkaloid widely used to improve the glucidic and lipidic profiles of patients with hypercholesterolemia, metabolic syndrome, and type 2 diabetes. The limitation of berberine seems to be its poor oral bioavailability, which is affected by the presence, in enterocytes, of P-glycoprotein – an active adenosine triphosphate (ATP)-consuming efflux protein that extrudes berberine into the intestinal lumen, thus limiting its absorption. According to some authors, silymarin, derived from Silybum marianum, could be considered a P-glycoprotein antagonist.

Aim

The study aimed to evaluate the role played by a possible P-glycoprotein antagonist (silymarin), when added to a product containing Berberis aristata extract, in terms of benefits to patients with type 2 diabetes.

Methods

The study enrolled 69 patients with type 2 diabetes in suboptimal glycemic control who were treated with diet, hypoglycemic drugs, and in cases of concomitant alterations of the lipid profile, hypolipidemic agents. The patients received an add-on therapy consisting of either a standardized extract of Berberis aristata (titrated in 85% berberine) corresponding to 1,000 mg/day of berberine, or Berberol®, a fixed combination containing the same standardized extract of Berberis aristata plus a standardized extract of Silybum marianum (titrated as >60% in silymarin), for a total intake of 1,000 mg/day of berberine and 210 mg/day of silymarin.

Results

Both treatments similarly improved fasting glucose, total cholesterol, low-density lipoprotein (LDL) cholesterol, triglyceride, and liver enzyme levels, whereas glycosylated hemoglobin (HbA_1c) values were reduced to a greater extent by the fixed combination.

Conclusion

The association of berberine and silymarin demonstrated to be more effective than berberine alone in reducing HbA_1c, when administered at the same dose and in the form of standardized extracts in type 2 diabetic patients.

Mechanism study of goldenseal-associated DNA damage

Goldenseal has been used for the treatment of a wide variety of ailments including gastrointestinal disturbances, urinary tract disorders, and inflammation. The five major alkaloid constituents in goldenseal are berberine, palmatine, hydrastine, hydrastinine, and canadine. When goldenseal was evaluated by the National Toxicology Program (NTP) in the standard 2-year bioassay, goldenseal induced an increase in liver tumors in rats and mice; however, the mechanism of goldenseal-associated liver carcinogenicity remains unknown. In this study, the toxicity of the five goldenseal alkaloid constituents was characterized, and their toxic potencies were compared. As measured by the Comet assay and the expression of γ-H2A.X, berberine, followed by palmatine, appeared to be the most potent DNA damage inducer in human hepatoma HepG2 cells. Berberine and palmatine suppressed the activities of both topoisomerase (Topo) I and II. In berberine-treated cells, DNA damage was shown to be directly associated with the inhibitory effect of Topo II, but not Topo I by silencing gene of Topo I or Topo II. In addition, DNA damage was also observed when cells were treated with commercially available goldenseal extracts and the extent of DNA damage was positively correlated to the berberine content. Our findings suggest that the Topo II inhibitory effect may contribute to berberine- and goldenseal-induced genotoxicity and tumorigenicity.

Berberine behind the thriller of marked symptomatic bradycardia

Patients with chronic aortic dissections are at high risk of catheter-induced complications. We report a Berberine is used in traditional Chinese medicine for the treatment of congestive heart failure, hypertension, diabetes, and dyslipidaemia and has a good safety profile. We report a case of a 53-year-old sportsman referred to our hospital for the onset of fatigue and dyspnoea upon exertion after he started berberine to treat hypercholesterolaemia. An electrocardiogram showed sinus bradycardia (45 bpm), first-degree atrioventricular block, and competitive junctional rhythm. An ergometric stress test showed slightly reduced chronotropic competence and the presence of runs of competitive junctional rhythm, atrial tachycardia, and sinus pauses in the recovery. After 10 d of wash-out from berberine, the patient experienced a complete resolution of symptoms, and an ergometric stress test showed good chronotropic competence. An electrocardiogram Holter showed a latent hypervagotonic state. This is the first case report that shows that berberine could present certain side effects in hypervagotonic people, even in the absence of a situation that could cause drug accumulation. Therefore, berberine’s use should be carefully weighed in hypervagotonic people due to the drug’s bradycardic and antiarrhythmic properties, which could became proarrhythmic, exposing patients to potential health risks.

Mesenteric lymphatic absorption and the pharmacokinetics of naringin and naringenin in the rat

The hypothesis for this study was that flavanoids and their glycoside are absorbed mainly through the portal vein to enter the liver for biotransformation and are only partially absorbed through the lymphatic duct. To verify this hypothesis, an unconscious, mesenteric lymphatic/portal vein/jugular vein/bile duct/duodenum-cannulated rat model was developed. Naringin was administered at dosages of 600 and 1000 mg/kg, and naringenin was given at 100 and 300 mg/kg by intraduodenal administration. Blood samples collected from the portal vein and jugular vein as well as lymphatic fluid were prepared by protein precipitation and then analyzed by high-performance liquid chromatography with photodiode array detection (HPLC-DAD). Analyses of these samples were doubly confirmed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The results show that, after intraduodenal administration, both compounds were mainly absorbed into portal blood rather than mesenteric lymph, and most of the intact analyte would be eliminated through bile excretion. The area under the concentration (AUC) ratio was defined to represent the absorption ratio for portal vein [AUC(portal)/AUC((portal+lymph))] and lymph fluid [AUC(lymph)/AUC((portal+lymph))]. The results indicate that the portal and lymphatic absorptions for naringin were around 95 and 5.0%, respectively. The respective absorptions for naringenin were around 98 and 2%, respectively.

Berberine on metabolic and cardiovascular risk factors: an analysis from preclinical evidences to clinical trials

INTRODUCTION

Type 2 diabetes mellitus and hypercholesterolemia have proven to give an increased incidence of cardiovascular diseases (CVD). Recent studies have suggested that the natural alkaloid berberine could have pharmacological activities potentially useful in diabetes and hypercholesterolemia management.

AREAS COVERED

The aim of this review is to evaluate the metabolic properties of the natural alkaloid berberine, and its potential application to the treatment of diabetes and CVD prevention.

EXPERT OPINION

Berberine proved to be effective in improving glycemic control and lipid profile. The modern investigation on berberine pharmacological activity is actually developing and numerous scientific evidences are actually in progress and reported in international congresses. The near future perspective is the isolation or neo-synthesis of berberine analogs with a higher bioavailability. The anti-hyperlipidemic and anti-diabetic effects of berberine have to be related to markers of improvement in organ damage in humans; longer trials are needed to better evaluate the safety profile of the molecule, when administered alone or in association with other anti-hyperlipidemic or anti-diabetic drugs, especially in the European population.

Effects of berberine and hwangryunhaedok-tang on oral bioavailability and pharmacokinetics of ciprofloxacin in rats

Hwangryunhaedok-Tang (HR) and berberine-containing single herbs are used to treat bacterial infection and inflammatory diseases in eastern Asia. The combination of berberine-containing herbal medicines and ciprofloxacin can be an excellent antibacterial chemotherapy against multidrug resistance bacteria. To evaluate the pretreatment effect of berberine and HR, vehicle, berberine (25 and 50 mg/kg/day), and HR (1.4 g/kg/day) were daily administered to rats for five consecutive days. On day 6, ciprofloxacin was administered (10 mg/kg, i.v. and 20 mg/kg, p.o.) to rats. To assess cotreatment effect of berberine and ciprofloxacin, berberine (50 mg/kg) and ciprofloxacin (20 mg/kg) were coadministered by single oral gavage. Pharmacokinetic data were estimated by noncompartmental model. Compared with ciprofloxacin alone (control group), coadministration of berberine (50 mg/kg) and ciprofloxacin significantly decreased C(max) of ciprofloxacin (P < 0.05). In addition, the pretreatment of berberine (50 mg/kg/day) and HR (1.4 g/kg/day) significantly decreased C(max) and AUC(0→∞), compared with control group (P < 0.05). The oral bioavailability of ciprofloxacin was reduced by cotreatment of berberine and pretreatment of berberine and HR. Our results suggest that the expression of P-glycoprotein and organic anion and/or organic cation transporters (OAT/OCT) could take a role in reduced oral bioavailability of ciprofloxacin by berberine and HR.

Isolation of gentiopicroside from Gentianae Radix and its pharmacokinetics on liver ischemia/reperfusion rats

ETHNOPHARMACOLOGICAL RELEVANCE

Gentiopicroside (GPS) is a secoiridoid glucoside isolated from the ethanol extract of Gentianae Radix with a content of 13%, which has been used for centuries in Chinese as a digestive aid.

AIM OF THE STUDY

This study investigates the pharmacokinetics of GPS and its metabolic pathway for the liver ischemia/reperfusion (I/R) in rats.

MATERIALS AND METHODS

The experimental animals were anesthetized intraperitoneally (i.p.) with a mixture of urethane (1.0 g/kg) and α-chloralose (0.1 g/kg). A midline laparatomy was performed and the liver hilum was gently exposed. All structures in the portal triad (hepatic artery, portal vein, and bile duct) to the left and median liver lobes were occluded with silk thread for 30 min. Ischemia was followed by a sudden reperfusion after removing the occluding threads. After 60 min reperfusion, the rats received a single intravenous 5 mg/kg dose of GPS.

RESULTS

The area under concentration curve (AUC) was significantly increased; however, the clearance (Cl) was significantly decreased in the liver I/R rats. Furthermore, after pretreated with SKF-525A (50 mg/kg, i.p.), a cytochrome P450 (CYP) inhibitor, AUC, elimination half-life (t(1/2)) and the mean residence time (MRT) of GPS in rat blood were significantly increased, suggesting that CYP was involved in the metabolism of GPS. For the group without liver I/R, GPS was administered at doses of 5 mg/kg and 100 mg/kg intravenously and orally, respectively. The pharmacokinetic results indicated that the AUC was 565±95.1 and 1163±273 min μg/mL and the t(1/2) of GPS was 71±9 and 106±17 min after intravenous and oral administration, respectively. The oral bioavailability of GPS was 10.3±2.4% in the rats.

CONCLUSIONS

The status of I/R might prolong the disposition of GPS, and the plasma concentration of GPS in the liver I/R injury rats was significantly increased. The increased body exposure of GPS in the treatment of liver I/R may result from the decreased metabolism of GPS mediated by CYP in the liver.

P-glycoprotein and its inhibition in tumors by phytochemicals derived from Chinese herbs

P-glycoprotein belongs to the family of ATP-binding cassette (ABC) transporters. It functions in cellular detoxification, pumping a wide range of xenobiotic compounds, including anticancer drugs out of the cell. In cancerous cells, P-glycoprotein confers resistance to a broad spectrum of anticancer agents, a phenomenon termed multidrug resistance. An attractive strategy for overcoming multidrug resistance is to block the transport function of P-glycoprotein and thus increase intracellular concentrations of anticancer drugs to lethal levels. Efforts to identify P-glycoprotein inhibitors have led to numerous candidates, none of which have passed clinical trials with cancer patients due to their high toxicity. The search for naturally inhibitory products from traditional Chinese medicine may be more promising because natural products are frequently less toxic than chemically synthesized substances. In this review, we give an overview of molecular and clinical aspects of P-glycoprotein and multidrug resistance in the context of cancer as well as Chinese herbs and phytochemicals showing inhibitory activity towards P-glycoprotein.

Antidiabetic properties of berberine: from cellular pharmacology to clinical effects

Berberine is an alkaloid that is highly concentrated in the roots, rhizomes, and stem bark of various plants. It affects glucose metabolism, increasing insulin secretion, stimulating glycolysis, suppressing adipogenesis, inhibiting mitochondrial function, activating the 5' adenosine monophosphate-activated protein kinase (AMPK) pathway, and increasing glycokinase activity. Berberine also increases glucose transporter-4 (GLUT-4) and glucagon-like peptide-1 (GLP-1) levels. On GLP-1 receptor activation, adenylyl cyclase is activated, and cyclic adenosine monophosphate is generated, leading to activation of second messenger pathways and closure of adenosine triphosphate-dependent potassium channels. Increased intracellular potassium causes depolarization, and calcium influx through the voltage-dependent calcium channels occurs. This intracellular calcium increase stimulates the migration and exocytosis of the insulin granules. In glucose-consuming tissues, such as adipose, or liver or muscle cells, berberine affects both GLUT-4 and retinol-binding protein-4 in favor of glucose uptake into cells; stimulates glycolysis by AMPK activation; and has effects on the peroxisome proliferator-activated receptor γ molecular targets and on the phosphorylation of insulin receptor substrate-1, finally resulting in decreased insulin resistance. Moreover, recent studies suggest that berberine could have a direct action on carbohydrate metabolism in the intestine. The antidiabetic and insulin-sensitizing effect of berberine has also been confirmed in a few relatively small, short-term clinical trials. The tolerability is high for low dosages, with some gastrointestinal complaints appearing to be associated with use of high dosages.

Pilot study on the additive effects of berberine and oral type 2 diabetes agents for patients with suboptimal glycemic control

BACKGROUND

Suboptimal glycemic control is a common situation in diabetes, regardless of the wide range of drugs available to reach glycemic targets. Basic research in diabetes is endeavoring to identify new actives working as insulin savers, use of which could delay the introduction of injectable insulin or reduce the insulin dose needed. Commonly available as a nutraceutical, berberine is a potential candidate.

METHODS AND RESULTS

Because its low oral bioavailability can be overcome by P-glycoprotein inhibitors like herbal polyphenols, we have tested the nutraceutical combination of Berberis aristata extract and Silybum marianum extract (Berberol(®)) in type 2 diabetes in terms of its additive effect when combined with a conventional oral regimen for patients with suboptimal glycemic control. After 90 days of treatment, the nutraceutical association had a positive effect on glycemic and lipid parameters, significantly reducing glycosylated hemoglobin, basal insulin, homeostatic model assessment of insulin resistance, total and low-density lipoprotein cholesterol, and triglycerides. A relevant effect was also observed in terms of liver function by measuring aspartate transaminase and alanine transaminase. The product had a good safety profile, with distinctive gastrointestinal side effects likely due to its acarbose-like action.

CONCLUSION

Although further studies should be carried out to confirm our data, Berberol could be considered a good candidate as an adjunctive treatment option in diabetes, especially in patients with suboptimal glycemic control.

CYP2D plays a major role in berberine metabolism in liver of mice and humans

Berberine is a widely used plant extract for gastrointestinal infections, and is reported to have potential benefits in treatment for diabetes and hypercholesterolemia. It has been suggested that interactions between berberine-containing products and cytochromes P450 (CYPs) exist, but little is known about which CYPs mediate the metabolism of berberine in vivo. In this study, berberine metabolites in urine and feces of mice were analyzed, and the role that CYPs play in producing these metabolites were characterized in liver microsomes from mice (MLM) and humans (HLM), as well as recombinant human CYPs. Eleven berberine metabolites were identified in mice, including 5 unconjugated metabolites, mainly in feces, and 6 glucuronide and sulfate conjugates, predominantly in urine. Three novel berberine metabolites were observed. Three unconjugated metabolites of berberine were produced by MLM, HLM, and recombinant human CYPs. CYP2D6 was the primary recombinant human CYP producing these metabolites, followed by CYP1A2, 3A4, 2E1 and CYP2C19. The metabolism of berberine in MLM and HLM was decreased the most by a CYP2D inhibitor, and moderately by inhibitors of CYP1A and 3A. CYP2D plays a major role in berberine biotransformation, therefore, CYP2D6 pharmacogenetics and potential drug-drug interactions should be considered when berberine is used.

Comparative pharmacokinetics of dehydroevodiamine and coptisine in rat plasma after oral administration of single herbs and Zuojinwan prescription

Zuojinwan, which consists of Rhizoma coptidis-Evodia rutaecarpa powder (6:1,g/g), is a traditional Chinese medicine (TCM) prescription, clinically used for the treatment of gastro-intestinal disorders. This study compared the pharmacokinetics of dehydroevodiamine and coptisine, the main active ingredients in Zuojinwan, in rats administrated with whole prescription or single herbs. Multiple blood concentration peaks were observed in the mean plasma-concentration curves. The pharmacokinetic parameters were quite different between single herbs and Zuojinwan prescription. Moreover, the mean plasma concentration of dehydroevodiamine increased and the one of coptisine decreased after combining, which was in accord with the clinical principle of TCM.

Berberine inhibits human hepatoma cell invasion without cytotoxicity in healthy hepatocytes

Conventional chemotherapy fails to cure metastatic hepatoma mainly due to its high hepatotoxicity. Many plant-derived agents have been accepted to effectively inhibit hepatoma cell invasion. However, the investigation that whether effectual plant-derived agents against invasive hepatoma cells exert unexpected cytotoxicity in healthy hepatocytes has been ignored. This study demonstrated that berberine exhibited significant cytotoxicity in HepG2 cells mainly through upregulation of reactive oxygen species (ROS) production but was ineffective in normal Chang liver cells. Berberine exerted anti-invasive effect on HepG2 cells through suppression of matrix metalloproteinase-9 (MMP-9) expression. Moreover, berberine could significantly inhibit the activity of PI3K-AKT and ERK pathways. Combination treatment of ERK pathway inhibitor PD98059 or AKT pathway inhibitor LY294002 and berberine could result in a synergistic reduction on MMP-9 expression along with an inhibition of cell invasion. Enhancement of ROS production by berberine had no influence on its suppressive effects on the activity of PI3K-AKT and ERK pathways, as well as MMP-9 expression and HepG2 cell invasion. In conclusion, our results suggest that berberine may be a potential alternative against invasive hepatoma cells through PI3K-AKT and ERK pathways-dependent downregulation of MMP-9 expression. This study also provides a previously neglected insight into the investigation of plant-derived agents-based therapy against tumor invasion with the consideration of damage to healthy cells.

Hepatoprotective activity of berberine is mediated by inhibition of TNF-α, COX-2, and iNOS expression in CCl(4)-intoxicated mice

This study investigated the protective effects of isoquinoline alkaloid berberine on the CCl(4)-induced hepatotoxicity in mice. Berberine was administered as a single dose at 5 and 10mg/kg intraperitoneally (i.p.), 1h before CCl(4) (10%, v/v in olive oil, 2ml/kg) injection and mice were euthanized 24h later. The rise in serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) in CCl(4)-intoxicated mice was markedly suppressed by berberine in a concentration-dependent manner. The decrease in hepatic activity of superoxide dismutase (Cu/Zn SOD) and an increase in lipid peroxidation were significantly prevented by berberine. Histopathological changes were reduced and the expression of tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) was markedly attenuated by berberine 10mg/mg. The results of this study indicate that berberine could be effective in protecting the liver from acute CCl(4)-induced injury. The hepatoprotective mechanisms of berberine may be related to the free radical scavenging and attenuation of oxidative/nitrosative stress, as well as to the inhibition of inflammatory response in the liver.

Physicochemical characterization of berberine chloride: a perspective in the development of a solution dosage form for oral delivery

The objective of the present research was to evaluate the physicochemical characteristics of berberine chloride and to assess the complexation of drug with 2-hydroxypropyl-β-cyclodextrin (HPβCD), a first step towards solution dosage form development. The parameters such as log P value were determined experimentally and compared with predicted values. The pH-dependent aqueous solubility and stability were investigated following standard protocols at 25°C and 37°C. Drug solubility enhancement was attempted utilizing both surfactants and cyclodextrins (CDs), and the drug/CD complexation was studied employing various techniques such as differential scanning calorimetry, Fourier transform infrared, nuclear magnetic resonance, and scanning electron microscopy. The experimental log P value suggested that the compound is fairly hydrophilic. Berberine chloride was found to be very stable up to 6 months at all pH and temperature conditions tested. Aqueous solubility of the drug was temperature dependent and exhibited highest solubility of 4.05 ± 0.09 mM in phosphate buffer (pH 7.0) at 25°C, demonstrating the effect of buffer salts on drug solubility. Decreased drug solubility was observed with increasing concentrations of ionic surfactants such as sodium lauryl sulfate and cetyl trimethyl ammonium bromide. Phase solubility studies demonstrated the formation of berberine chloride-HPβCD inclusion complex with 1:1 stoichiometry, and the aqueous solubility of the drug improved almost 4.5-fold in the presence of 20% HPβCD. The complexation efficiency values indicated that the drug has at least threefold greater affinity for hydroxypropyl-β-CD compared to randomly methylated-β-CD. The characterization techniques confirmed inclusion complex formation between berberine chloride and HPβCD and demonstrated the feasibility of developing an oral solution dosage form of the drug.

Oxidative demethylenation and subsequent glucuronidation are the major metabolic pathways of berberine in rats

Present study was designed to explore roles of metabolic clearance in the disposition of berberine (BBR) in rats, with a focus on oxidative metabolism and subsequent glucuronidation. Plasma from rats after intravenous administration of BBR was collected to identify and quantify BBR and its major metabolites. The major circulating metabolites of BBR were oxidative metabolites M1 (via demethylation) and M2 (via demethylenation) and their corresponding glucuronides, with M2-glucuronide approximately 24-fold higher than M1-glucuronide. Incubations with rat liver microsomes were conducted to examine formation kinetics of two oxidative metabolites-M1 and M2, and depletion kinetics of M1 and M2, leading to the formation of glucuronide conjugates. Efforts were also made to examine roles of key CYPs and UGTs isoforms responsible for BBR metabolism using known chemical inhibitors and/or substrates. In vitro, the formation of M1 and M2 were comparable and multiple CYP enzymes were involved. In contrast, the glucuronidation of M2 was much faster than that of M1. Inhibition studies using well-characterized UGT substrates suggested both M1 and M2 could be glucuronidated by UGT1A1 and UGT2B1 while M2 glucuronidation was favored by UGT1A1. In summary, oxidative demethylenation and the subsequent glucuronidation were the major metabolic pathways of BBR in rats.

An in vivo microdialysis measurement of harpagoside in rat blood and bile for predicting hepatobiliary excretion and its interaction with cyclosporin A and verapamil

Harpagoside, a major bioactive iridoid glucoside in genus Scrophularia, has been widely used in clinical practice for the treatment of pain in the joints and lower back for its neuroprotective and anti-inflammation activities. To investigate the pharmacokinetics and hepatobiliary excretion, an in vivo microdialysis method coupled with high performance liquid chromatography was developed to monitor the concentration of harpagoside in blood and bile. The harpagoside bile-to-blood distribution ratio (AUC(bile)/AUC(blood)) up to 986.28+/-78.46 significantly decreased to 6.41+/-0.56 or 221.20+/-18.92 after co-administration of cyclosporin A or verapamil. The results indicated that harpagoside went through concentrative elimination from the bile which was probably regulated by P-glucoprotein, providing possible clinical trials of co-administration of transporter inhibitors to decrease drug efflux, thus to enhance the curative effects.

The natural product berberine is a human prolyl oligopeptidase inhibitor

Prolyl oligopeptidase is a cytosolic serine peptidase that hydrolyzes proline-containing peptides at the carboxy terminus. This peptidase has been associated with schizophrenia, bipolar affective disorder, and related neuropsychiatric disorders, and therefore may have important clinical implications. Among the strategies used to find novel prolyl oligopeptidase inhibitors, traditional Chinese medicinal plants provide a rich source of unexplored compounds. We used (19)F NMR spectroscopy to search for new prolyl oligopeptidase inhibitors in a library of traditional Chinese medicine plant extracts. Several extracts were identified as powerful inhibitors of this peptidase. The alkaloid berberine was the prolyl oligopeptidase inhibitory molecule isolated from Rhizoma coptidis extract. Berberine inhibited prolyl oligopeptidase in a dose-dependent manner. As berberine is a natural compound that has been safely administered to humans, it opens up new perspectives for the treatment of neuropsychiatric diseases. The results described herein suggest that the initiation of clinical trials in patients with schizophrenia, bipolar affective disorder, or related diseases in which cognitive capabilities are affected should be undertaken with either the extract or pure BBR.

Mechanisms of berberine (natural yellow 18)-induced mitochondrial dysfunction: interaction with the adenine nucleotide translocator

Berberine [Natural Yellow 18, 5,6-dihydro-9,10-dimethoxybenzo(g)-1,3-benzodioxolo (5,6-a) quinolizinium] is an alkaloid present in plants of the Berberidaceae family and used in traditional Chinese and North American medicine. We have previously demonstrated that berberine causes mitochondrial depolarization and fragmentation, with simultaneous increase in oxidative stress. We also demonstrated that berberine causes an inhibition of mitochondrial respiration and a decrease on calcium loading capacity through induction of the mitochondrial permeability transition (MPT). The objective of the present work is to investigate a common target for both induction of the MPT and inhibition of respiration. The hypothesis is that berberine induces the MPT through interacting with the adenine nucleotide translocator (ANT). By measuring induction of the MPT through increased mitochondrial swelling, membrane depolarization and loss of calcium retention, we observed that the effects of berberine were not inhibited by bongkrekic acid although adenosine diphosphate (ADP)/oligomycin completely prevented the MPT. Also, we observed that berberine increased the depolarization effect of oleic acid on liver mitochondria. The initial depolarization observed when berberine is added to mitochondria was not affected by ANT inhibitors. Taken together, we propose that berberine acts on the ANT, altering the binding of the protein to bongkrekic acid but not to cyclosporin A or ADP. It is also clear that the membrane potential is required for berberine effects, most likely for allowing for its mitochondrial accumulation. Mitochondrial effects of berberine can be relevant not only for its proposed antitumor activity but also for the assessment of its organ toxicity, depending on factors such as tissue accumulation or delivery.

Effect of ion-pair formation with bile salts on the in vitro cellular transport of berberine

The objective of this study was to examine the effect of ion-pair complexation with endogenous bile salts on the transport of a quarternary ammonium organic cationic (OC) drug, berberine, across the Caco-2 and LLC-PK1 cell monolayers. The basolateral-to-apical (BL-AP) transport of berberine in Caco-2 cells was temperature dependent and 10-fold higher than that of the apical-to-basolateral (AP-BL) transport. Similar results were observed for the transport of berberine across the LLC-PK1 cells. Moreover, the BL-AP transport in the Caco-2 cells was significantly reduced by the cis-presence of P-glycoprotein (P-gp) inhibitors such as cyclosporine A, verapamil, and digoxin. These results suggest that an efflux transporter, probably P-gp, is involved in the Caco-2 cell transport. The Km and Vmax values for the carrier-mediated transport were estimated to be 83.4 mM and 7640 pmole/h/cm2, respectively. The apparent partition coefficient (APC) of berberine between n-octanol and a phosphate buffer (pH 7.4) was increased by the presence of an organic anion (OA), taurodeoxycholate (TDC, a bile salt), suggesting the formation of a lipophilic ion-pair complex between an OC (berberine) and an OA (TDC). Despite the ion-pair complexation, however, the BL-AP transport of berberine across the Caco-2 and LLC-PK1 cells was not altered by the cis-presence of bile salts or the rat bile juice. This is consistent with the reportedly unaltered secretory transport of a quarternary ammonium compound, tributylmethylammonium (TBuMA), across the Caco-2 cell monolayers in the cis-presence of bile salts or the rat bile juice, but not with our previous report in which the secretory transport of TBuMA across the LLC-PK1 cell was increased in the cis-presence of TDC. Therefore, the effect of ion-pair formation with the bile components or bile salts on the secretory transport of OCs appears to depend on the molecular properties of OCs (e.g., molecular weight, lipophilicity and affinity to relevant transporters) and the characteristics of cell strains (e.g., expression and contribution of responsible transporters to the transport).

Vectorial transport of the plant alkaloid berberine by double-transfected cells expressing the human organic cation transporter 1 (OCT1, SLC22A1) and the efflux pump MDR1 P-glycoprotein (ABCB1)

An important function of hepatocytes is the biliary elimination of endogenous and xenobiotic small molecules, many of which are organic cations. To study this vectorial transport of organic cations, we constructed a double-transfected Madin-Darby canine kidney strain II (MDCKII) cell line permanently expressing the human organic cation transporter 1 (OCT1, SLC22A1) in the basolateral membrane and MDR1 P-glycoprotein (MDR1 P-gp, ABCB1), an adenosine triphosphate (ATP)-dependent efflux pump for organic cations, in the apical membrane. Additionally, MDCKII single transfectants stably expressing OCT1, MDR1 P-gp, or human organic cation transporter 2 (OCT2, SLC22A2) were generated. Antisera directed against OCT1 or OCT2 specifically detected OCT1 in the basolateral membrane of human hepatocytes, OCT2 in tubular epithelial cells of human kidney, and the respective recombinant transporter in the basolateral membrane of MDCKII transfectants. We identified the lipophilic organic cation berberine, a fluorescent plant alkaloid exhibiting a broad range of biological activities, as substrate of OCT1 and OCT2 with Michaelis-Menten constants of 14.8 microM and 4.4 microM, respectively. Berberine also inhibited the uptake of the prototypic cations tetraethylammonium and 1-methyl-4-phenylpyridinium by MDCK-OCT1 and MDCK-OCT2 transfectants. When transfected cells were grown polarized on permeable filter supports, berberine was transferred from the basolateral to the apical compartments many times faster by MDCK-OCT1/MDR1 P-gp double transfectants than by MDCK-OCT1 or MDCK-MDR1 P-gp single transfectants. The specific MDR1 P-gp inhibitor, zosuquidar trihydrochloride (LY335979), strongly inhibited berberine efflux into the apical compartment. The MDCK-OCT1/MDR1 P-gp double transfectants may be useful to identify additional cationic substrates and inhibitors of OCT1 and MDR1 P-gp, including drug candidates.

Quantitative determination of unbound cefoperazone in rat bile using microdialysis and liquid chromatography

Cefoperazone is a third generation cephalosporin antibiotic with a broad spectrum against gram-positive and gram-negative bacteria. It is clinically effective in the treatment of the biliary tract infections. In the present study, we utilized microdialysis sampling technique with shunt linear probe for continuous monitoring levels of cefoperazone from rat biliary ducts. The effects of berberine (a potential P-glycoprotein enhancer) pretreatment were also evaluated. Analysis of cefoperazone in the dialysates was achieved using a reversed phase RP-18 column (250 mm x 4.6 mm i.d.; particle size 5 microm) maintained at ambient temperature. The mobile phase comprised 100 mM monosodium phosphate (pH 5.5)-methanol (70:30, v/v), and the flow rate of the mobile phase was 1 ml/min. The UV detector wavelength was set at 254 nm. The area under the concentration-time curve and elimination half-life of cefoperazone were about 242.3+/-13.4 min mg/ml and 64.1+/-28.2 min, respectively. No significant effect was showed on the pharmacokinetics of cefoperazone with berberine pretreatment. This study represents a successful application of biliary microdialysis sampling technique, which is feasible for pharmacokinetic and biliary drug excretion studies.

Recent applications of liquid chromatography-mass spectrometry in natural products bioanalysis

Natural flavonoids, alkaloids, saponins and sesquiterpenoids have been extensively investigated because of their biological and physiological significances, as well as their promising clinical uses. It is necessary to monitor them or their metabolites in biological fluids for both pre-clinical studies and routine clinical uses. The successful hyphenation of LC and MS, which was thought as "the bird wants to marry with fish", has been conducted widely in biological samples analysis. This present paper reviewed the feasibility of LC-MS techniques in the identification and quantification of natural products (flavonoids, alkaloids, saponins and sesquiterpenoids) in biological fluids, dealing with sample preparation, LC techniques, suitability of different MS techniques. Perspective of LC-MS was also discussed to show the potential of this technology. The citations cover the period 2002-2006. We conclude that LC-MS is an extremely powerful tool for the analysis of natural products in biological samples.

Quaternary protoberberine alkaloids

This contribution reviews some general aspects of the quaternary iminium protoberberine alkaloids. The alkaloids represent a very extensive group of secondary metabolites with diverse structures, distribution in nature, and biological effects. The quaternary protoberberine alkaloids (QPA), derived from the 5,6-dihydrodibenzo[a,g]quinolizinium system, belong to a large class of isoquinoline alkaloids. Following a general introduction, the plant sources of QPA, their biosynthesis, and procedures for their isolation are discussed. Analytical methods and spectral data are summarized with emphasis on NMR spectroscopy. The reactivity of QPA is characterized by the sensitivity of the iminium bond CN(+) to nucleophilic attack. The addition of various nucleophiles to the protoberberine skeleton is discussed. An extended discussion of the principal chemical reactivity is included since this governs interactions with biological targets. Quaternary protoberberine alkaloids and some related compounds exhibit considerable biological activities. Recently reported structural studies indicate that the QPA interact with nucleic acids predominantly as intercalators or minor groove binders. Currently, investigations in many laboratories worldwide are focused on the antibacterial and antimalarial activity, cytotoxicity, and potential genotoxicity of QPA.