Reduced system exposures of total rhein and baicalin after combinatory oral administration of rhein, baicalin and berberine to beagle dogs and rats

Baicalin mediated regulation of key signaling pathways in cancer

Baicalin has been widely investigated against different types of malignancies both at the cellular and molecular levels over the past few years. Due to its remarkable anti-proliferative potential in numerous cancer cell lines, it has created immense interest as a potential chemotherapeutic modality compared to other flavonoids. Thus, this review focuses on the recent accomplishments of baicalin and its limitations in cancer prevention and treatment. Further, combination studies and nanoformulations using baicalin to treat cancer along with the metabolism, bioavailability, toxicity, and pharmacokinetics have been discussed. The present review explains biological source, and anti-proliferative potential of baicalin against cancers including breast, colon, hepatic, leukemia, lung, and skin, as well as the relevant mechanism of action to modulate diverse signaling pathways including apoptosis, cell cycle, invasion, and migration, angiogenesis, and autophagy. The anticancer mechanism of baicalin in orthotropic and xenograft mice models have been deliberated. The combination studies of baicalin in novel therapies as chemotherapeutic adjuvants have also been summarized. The low bioavailability, fast metabolism, and poor solubility, and other significant factors that limit the clinical use of baicalin have been examined as a challenge. The improvement in the pharmacokinetics and pharmacodynamics of baicalin with newer approaches and the gaps are highlighted, which could establish baicalin as an effective and safe compound for cancer treatment as well as help to translate its potential from bench to bedside.

Pharmacokinetics and Bioavailability Enhancement of Baicalin: A Review

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

The Influence of Compatibility of Rhubarb and Radix Scutellariae on the Pharmacokinetics of Anthraquinones and Flavonoids in Rat Plasma

BACKGROUND AND OBJECTIVES

Rhubarb-Radix scutellariae is a classic herb pair, which is commonly used to clear away heat and toxin in clinic. The aim of this study was to investigate the influence of compatibility of Rhubarb and Radix scutellariae on the pharmacokinetic behaviors of anthraquinones and flavonoids in rat plasma.

METHODS

Eighteen rats were randomly divided into three groups, and were orally administered Rhubarb and/or Radix scutellariae extracts. A sensitive and rapid UPLC-MS/MS method was developed and validated to determine the concentrations of baicalin, baicalein, wogonside, wogonin, rhein, and emodin in rat plasma. The concentrations of phase II conjugates of flavonoid aglycones and anthraquinone aglycones were also determined after hydrolyzing the plasma with sulfatase.

RESULTS

Compared with administration of Radix scutellariae alone, co-administration of Rhubarb significantly decreased the first maximum plasma concentration (C _max1) of baicalin, wogonside, and the phase II conjugates of baicalein, wogonin to 46.40, 61.27, 41.49, and 20.50%, respectively. The area under the plasma concentration-time curve from time zero to infinity (AUC_0-∞) was significantly decreased from 82.60 ± 20.22 to 51.91 ± 7.46 μM·h for rhein and 276.83 ± 98.02 to 175.42 ± 86.82 μM·h for the phase II conjugates of wogonin after compatibility. The time to reach the first maximum plasma concentration (T _max1) of anthraquinones was shortened and the second peak of anthraquinones disappeared after compatibility.

CONCLUSIONS

Compatibility of Rhubarb and Radix scutellariae can significantly affect the pharmacokinetic behaviors of characteristic constituents of the two herbs. The cause of these pharmacokinetic differences was further discussed combined with the in vivo ADME (absorption, disposition, metabolism, and excretion) processes of anthraquinones and flavonoids.

Alleviating the Intestinal Absorption of Rhein in Rhubarb through Herb Compatibility in Tiaowei Chengqi Tang in Caco-2 Cells

Tiaowei Chengqi Tang (TWCQT) is composed of rhubarb, processed liquorice, and Natrii Sulfas, which is used as a purgative in traditional Chinese medicine (TCM). This study focused on the intestinal absorption of rhein in disassembly of the TWCQT extracts through the Caco-2 cell monolayer model to explicate the possible detoxification mechanism of herb-herb compatibility in TWCQT. The results showed that the intestinal absorption of rhein occurred through active diffusion, and rhein might be composed of breast cancer resistance protein (BCRP) substrates. The extract of processed liquorice increased the exclusion rate and reduced intracellular uptake of rhein. The consistent results observed in TWCQT further implied that processed liquorice in TWCQT could suppress the absorption of rhein across the Caco-2 cell monolayer. It has therefore been concluded that the active ingredients of processed liquorice may play a critical role in reducing the intestinal absorption of rhein to alleviate the toxicity of rhubarb in TWCQT. Because of BCRP's involvement in rhein transport, we conjectured that some components in processed liquorice could inhibit the transport of rhein, possibly by mediating BCRP. These results would provide new insight into this ancient drug combination in toxicity reduction and clinical use.

Use of liquid chromatography hybrid triple-quadrupole mass spectrometry for the detection of emodin metabolites in rat bile and urine

Emodin is the representative form of rhubarb, which is widely used in traditional Chinese medicine for the treatment of purgative, anti-inflammatory, antioxidative and antiviral, etc. Previous reports demonstrated that emodin glucuronide was the major metabolite in plasma. Owing to the extensive conjugation reactions of polyphenols, the aim of this study was to identify the metabolites of emodin in rat bile and urine. Neutral loss and precursor ion scan methods of triple-quadrupole mass spectrometer revealed 13 conjugated metabolites in rat bile and 22 metabolites in rat urine, which included four phase I and 18 phase II metabolites. The major metabolites in rat biosamples were emodin glucuronoconjugates. Moreover, rhein monoglucuronide, chrysophanol monoglucuronide and rhein sulfate were proposed for the first time after oral administration of emodin. Overall, liquid chromatography hybrid triple-quadrupole mass spectrometry analysis leads to the discovery of several novel emodin metabolites in rat bile and urine and underscores that conjugated with glucuronic acid is the main metabolic pathway.

Pharmacokinetics of mangiferin and its metabolite-norathyriol, Part 2: Influence of UGT, CYP450, P-gp, and enterobacteria and the potential interaction in Rhizoma Anemarrhenae decoction with timosaponin B2 as the major contributor

The poor bioavailability of mangiferin (MGF) is a major obstacle on its further development. Aimed to illustrate the underlying mechanism and improve its poor exposure, the compared PK profiles of MGF and norathyriol (NTR) after different MGF preparation were performed: pure MGF, the Rhizoma Anemarrhenae (Zhi-mu) decoction, MGF, and timosaponin B2 (TB-2) combination. Furthermore, the potential contributing factors, including uridine diphosphoglucuronosyltransferase (UGT), cytochrome P450 (CYP450), P-gp, and enterobacterial were investigated by comparing the PK profiles with and without the corresponding inhibitors or in different rat models. After taking MGF, CYP450 and UGT inhibition could decrease MGF and NTR exposure; P-gp inhibition slightly enhanced (48%) MGF exposure, whereas more apparent for the improved NTR exposure (302%); enterobacterial inhibition almost completely stopped the NTR production, but no such effect was observed for MGF. Compared with the limited improvement by the abovementioned inhibition, the MGF and NTR exposure could significantly increase by 11.5- and 5.9-fold in the Zhi-mu decoction compared with the MGF treatment, probably contributed to TB-2 as an absorption enhancer because the MGF and TB-2 combination produced a similar level of improvement on the PK paremeters of MGF and NTR to the herb treatment. Likewise, most of the effects by UGT, CYP450, P-gp, and enterobacteria followed a similar variation tendency between them. Therefore, the poor bioavailability of MGF possibly mainly attributed to its poor membrane permeability, but not transporters or metabolic enzymes, and the compatibility of MGF and TB-2 could probably expand the prospective application of MGF by improving its bioavailability. © 2016 BioFactors, 42(5):545-555, 2016.

In Vivo and in Vitro Study on Drug-Drug Interaction of Lovastatin and Berberine from Pharmacokinetic and HepG2 Cell Metabolism Studies

Background: We assumed that the pharmacokinetics of lovastatin could be changed by the induction effect of berberine. Methods: An UPLC-MS/MS method was developed and validated for the pharmacokinetics tudy of lovastatin to investigate the in vivo drug-drug interactions between lovastatin and berberine. SD male rats were random divided into lovastatin group and berberine induced prior to lovastatin group for the in vivo pharmacokinetic studies. Meanwhile HepG2 cells were induced by berberine for three days to study the metabolism of lovastatin. Results: The AUC (p < 0.01) and C_max (p < 0.01) could be significantly decreased in the berberine-induced group in vivo, and the metabolic activity of HepG2 cell ccould be increased by berberine induction in vitro. The metabolism parameters of lovastatin such as CL, V_max and K_m were increased after the induction of berberine. From the pharmacokinetic study of lovastatin induced with berberine, we obtained pharmacokinetic parameters which are compliance with the metabolic parameters of lovastatin in HepG2 cells with berberine induction in vitro. Conclusions: From the in vivo pharmacokinetics study and the HepG2 cell metabolism study in vitro, berberine could be an inducer for the metabolism of lovastatin according to our previous research on berberine induction effects on HepG2 cells, which may be relevant to the fact that berberine possesses induction effects through the CYP 450 3A4 enzyme.

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.

Study on biopharmaceutics classification and oral bioavailability of a novel multikinase inhibitor NCE for cancer therapy

Specific biopharmaceutics classification investigation and study on phamacokinetic profile of a novel drug candidate (2-methylcarbamoyl-4-{4-[3- (trifluoromethyl) benzamido] phenoxy} pyridinium 4-methylbenzenesulfonate monohydrate, NCE) were carried out. Equilibrium solubility and intrinsic dissolution rate (IDR) of NCE were estimated in different phosphate buffers. Effective intestinal permeability (P(eff)) of NCE was determined using single-pass intestinal perfusion technique in rat duodenum, jejunum and ileum at three concentrations. Theophylline (high permeability) and ranitidine (low permeability) were also applied to access the permeability of NCE as reference compounds. The bioavailability after intragastrical and intravenous administration was measured in beagle dogs. The solubility of NCE in tested phosphate buffers was quite low with the maximum solubility of 81.73 μg/mL at pH 1.0. The intrinsic dissolution ratio of NCE was 1 × 10⁻⁴ mg·min⁻¹·cm⁻². The P(eff) value of NCE in all intestinal segments was more proximate to the high-permeability reference theophylline. Therefore, NCE was classified as class II drug according to Biopharmaceutics Classification System due to its low solubility and high intestinal permeability. In addition, concentration-dependent permeability was not observed in all the segments, indicating that there might be passive transportation for NCE. The absolute oral bioavailability of NCE in beagle dogs was 26.75%. Therefore, dissolution promotion will be crucial for oral formulation development and intravenous administration route will also be suggested for further NCE formulation development. All the data would provide a reference for biopharmaceutics classification research of other novel drug candidates.

Rhein, a natural anthraquinone derivative, attenuates the activation of pancreatic stellate cells and ameliorates pancreatic fibrosis in mice with experimental chronic pancreatitis

Pancreatic fibrosis, a prominent histopathological feature of chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma, is essentially a dynamic process that leads to irreversible scarring of parenchymal tissues of the pancreas. Though the exact mechanisms of its initiation and development are poorly understood, recent studies suggested that the activation of pancreatic stellate cells (PSCs) plays a critical role in eliciting such active course of fibrogenesis. Anthraquinone compounds possess anti-inflammatory bioactivities whereas its natural derivative rhein has been shown to effectively reduce tissue edema and free-radical production in rat models of inflammatory conditions. Apart from its anti-inflammatory properties, rhein actually exerts strong anti-fibrotic effects in our current in-vivo and in-vitro experiments. In the mouse model of cerulein-induced CP, prolonged administration of rhein at 50 mg/kg/day significantly decreased immunoreactivities of the principal fibrotic activators alpha-smooth muscle actin (α-SMA) and transforming growth factor-beta (TGF-β) on pancreatic sections implicating the activation of PSCs, which is the central tread to fibrogenesis, was attenuated. Consequently, the overwhelmed deposition of extracellular matrix proteins fibronectin 1 (FN1) and type I collagen (COL I-α1) in exocrine parenchyma was found accordingly reduced. In addition, the expression levels of sonic hedgehog (SHH), which plays important roles in molecular modulation of various fibrotic processes, and its immediate effector GLI1 in pancreatic tissues were positively correlated to the degree of cerulein-induced fibrosis. Such up-regulation of SHH signaling was restrained in rhein-treated CP mice. In cultured PSCs, we demonstrated that the expression levels of TGF-β-stimulated fibrogenic markers including α-SMA, FN1 and COL I-α1 as well as SHH were all notably suppressed by the application of rhein at 10 μM. The present study firstly reported that rhein attenuates PSC activation and suppresses SHH/GLI1 signaling in pancreatic fibrosis. With strong anti-fibrotic effects provided, rhein can be a potential remedy for fibrotic and/or PSC-related pathologies in the pancreas.