Pharmacokinetics of baicalein, baicalin and wogonin after oral administration of a standardized extract ofScutellaria baicalensis, PF-2405 in rats

The 8-bromobaicalein alleviated chikungunya-induced musculoskeletal inflammation and reduced the viral load in healthy adult mice

Chikungunya virus is a re-emerging arbovirus that has caused epidemic outbreaks in recent decades. Patients in older age groups with high viral load and severe immunologic response during acute infection are likely to develop chronic arthritis and severe joint pain. Currently, no antiviral drug is available. Previous studies suggested that a flavone derivative, 8-bromobaicalein, was a potential dengue and Zika replication inhibitor in a cell-based system targeting flaviviral polymerase. Here we characterized that 8-bromobaicalein inhibited chikungunya virus replication with EC50 of 0.49 ± 0.11 µM in Vero cells. The molecular target predicted at viral nsP1 methyltransferase using molecular binding and fragment molecular orbital calculation. Additionally, oral administration of 250 mg/kg twice daily treatment alleviated chikungunya-induced musculoskeletal inflammation and reduced viral load in healthy adult mice. Pharmacokinetic analysis indicated that the 250 mg/kg administration maintained the compound level above EC99.9 for 12 h. Therefore, 8-bromobaicalein should be a potential candidate for further development as a pan-arboviral drug.

Scutellaria baicalensis enhances 5-fluorouracil-based chemotherapy via inhibition of proliferative signaling pathways

Fluoropyridine-based chemotherapy remains the most widely used treatment for colorectal cancer (CRC). In this study, we investigated the mechanism by which the natural product Scutellaria baicalensis (Huang Qin; HQ) and one of its main components baicalin enhanced 5-fluorouracil (5-FU) antitumor activity against CRC. Cell proliferation assays, cell cycle analysis, reverse-phase protein array (RPPA) analysis, immunoblot analysis, and qRT-PCR were performed to investigate the mechanism(s) of action of HQ and its active components on growth of CRC cells. HQ exhibited in vitro antiproliferative activity against drug resistant human CRC cells, against human and mouse CRC cells with different genetic backgrounds and normal human colon epithelial cells. In vivo animal models were used to document the antitumor activity of HQ and baicalin. The mechanism of growth inhibitory activity of HQ is due to inhibition of proliferative signaling pathways including the CDK-RB pathway. In addition, HQ enhanced the antitumor effects of 5-FU and capecitabine in vivo. Furthermore, we identified baicalin as an active component of HQ. The combination of baicalin and 5-FU demonstrated synergistic activity against 5-FU-resistant RKO-R10 cells. The combination significantly inhibited in vivo tumor growth greater than each treatment alone. RPPA results showed that the signaling pathway alterations in CRC cells were similar following HQ and baicalin treatment. Together, these results indicate that HQ and its component baicalin enhance the effect of 5-fluorouracil-based chemotherapy via inhibition of CDK-RB pathway. These findings may provide the rational basis for developing agents that can overcome the development of cellular drug resistance. Video Abstract.

Pharmacological properties of total flavonoids in Scutellaria baicalensis for the treatment of cardiovascular diseases

BACKGROUND

Scutellaria baicalensis, a medicinal herb belonging to the Lamiaceae family, has been recorded in the Chinese, European, and British Pharmacopoeias. The medicinal properties of this plant are attributed to the total flavonoids of Scutellaria baicalensis (TFSB), particularly the main component, baicalin. This study provides a systematic and comprehensive list of the identified TFSB components and their chemical structures. The quality control process, pharmacokinetics, clinical application, and safety of Scutellaria baicalensis are discussed, and its pharmacological effect on cardiovascular diseases (CVDs) is detailed. Finally, the future research trends and prospects of this medicinal plant are provided.

METHODS

The Chinese and English papers related to TFSB were collected from the PubMed and CNKI databases using the relevant keywords. To highlight the pharmacological mechanism, clinical application, and safety of TFSB, the collected articles were screened and classified based on their research content.

RESULTS

TFSB contains at least 100 different kinds of flavonoids, of which baicalin, baicalein, wogonin, wogonoside, scutellarin, and scutellarein are the main active ingredients. The preparation process of TFSB is relatively well established, and the extraction rate can be significantly increased by enzymatic pretreatment and ultrasonication. The low oral availability of TFSB may be effectively enhanced using nanoformulations. The available pharmacokinetic data show that flavonoid glycosides and aglycones with the same parent nucleus may be converted to structures that are conducive to absorption in vivo. Moreover, TFSB can protect against CVDs by inhibiting apoptosis, regulating oxidative stress response, participating in inflammatory response, protecting against myocardial fibrosis, inhibiting myocardial hypertrophy, and regulating blood vessels. In terms of clinical application and animal safety, the available studies show that TFSB can be applied in a wide range of clinical treatments and is safe to use is animals.

CONCLUSION

This article systematically reviews the therapeutic effect and underlying pharmacological mechanism of TFSB against CVDs. The available studies clearly suggest that TFSB has great potential for the treatment of CVDs and is worthy of in-depth research and development.

Inhibition of Lipoxygenases Showed No Benefit for the Musculoskeletal System in Estrogen Deficient Rats

BACKGROUND

In previous studies, we reported the beneficial impact of two lipoxygenase-inhibitors, Baicalein and Zileuton, on osteoporotic bone in a postmenopausal rat model. Whereas subcutaneous Baicalein predominantly improved cortical bone, Zileuton enhanced vertebral and femoral trabecular bone. In this study, we aimed to reveal whether the oral administration of Baicalein caused similar effects on bone and whether a combined administration of Baicalein and Zileuton could act synergistically to ameliorate the formerly reported effects in the musculoskeletal system.

METHODS

We treated ovariectomized (OVX) female Sprague-Dawley rats either with Baicalein (10mg/kg BW), Zileuton (10mg/kg BW) or a combination of both (each 10mg/kg BW) for 13 weeks and compared with untreated OVX and NON-OVX groups (n=12-16 rats per group). Lumbar vertebral bodies and femora were analyzed. Tibiae were osteotomized, plate-stabilized (at week 8 after OVX) and likewise analyzed by biomechanical, histological, micro-computed tomographical and ashing tests. The skeletal muscle structure was analyzed.

RESULTS

Oral administration of Baicalein did not confirm the reported favorable cortical effects in neither vertebra nor femur. Zileuton showed a beneficial effect on trabecular vertebra, while the femur was negatively affected. Callus formation was enhanced by all treatments; however, its density and biomechanical properties were unaltered. Lipoxygenase inhibition did not show a beneficial effect on skeletal muscle. The combination therapy did not ameliorate OVX-induced osteoporosis but induced even more bone loss.

CONCLUSIONS

The preventive anti-osteoporotic treatments with two lipoxygenase inhibitors applied either alone or in combination showed no benefit for the musculoskeletal system in estrogen deficient rats.

Simultaneous determination of asarinin, β-eudesmol, and wogonin in rats using ultraperformance liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic studies following administration of standards and Gumiganghwal-tang

Asarinin, β-eudesmol, and wogonin have common antiangiogenic activities and have the potential for use in chemotherapy. Besides, they are multivalent substances that are combined in various herbal medicines. The purpose of this study was to develop a method for simultaneous analysis of asarinin, β-eudesmol, and wogonin, which are representative pharmacological components of Asarum heterotropoides, Atractylodes lancea, and Scutellaria baicalensis, respectively, in rat biosamples using ultraperformance liquid chromatography-tandem mass spectrometry. The three components were separated using 5 mm aqueous ammonium acetate containing 0.1% formic acid and acetonitrile as a mobile phase, equipped with a KINETEX core-shell C₁₈ column. The analysis was quantitated on a triple-quadrupole mass-spectrometer employing electrospray ionization, and operated in the multiple reaction monitoring mode. The chromatograms showed high resolution, sensitivity, and selectivity with no interference with plasma, urine, and feces constituents. The developed analytical method satisfied international guidance criteria and could be successfully applied to the pharmacokinetic (PK) studies evaluating oral bioavailability of asarinin, β-eudesmol, and wogonin after oral and intravenous administration and their urinary and fecal excretion ratios after oral administration to rats. Furthermore, the analysis was extended to PK studies following oral administration of Gumiganghwal-tang. This study was the first simultaneous analysis of the aforesaid three constituents in rat plasma, urine, and feces that also determined their PK parameters.

Interactions between Ginkgo biloba L. and Scutellaria baicalensis Georgi in multicomponent mixtures towards cholinesterase inhibition and ROS scavenging

This study gives new insights to understand the type of interactions between Ginkgo biloba L. and Scutellaria baicalensis Georgi, two Chinese medicinal plants with well documented neuroprotective effects, on three targets in Alzheimer's disease (AD): acetylcholinesterase (AChE) and butyrylcholnesterase (BuChE) inhibition and hydrogen peroxide scavenging. Individual samples, binary mixtures with different proportions of both plant species, and also a commercial multicomponent combination containing both plants together with unroasted Coffea arabica L. and quercetin-3-O-rutinoside were used to perform this in vitro evaluation. Sample phenolic profiles were also determined by HPLC-DAD, showing the presence of several flavonoid glycosides, phenolic acids and a methylxanthine. In order to investigate the possible synergism/antagonism interaction, data obtained were analyzed by CompuSyn software. The results showed that G. biloba and S. baicalensis alone display better activities than in mixtures, most of the interactions exhibiting different degrees of antagonism. A slight synergism interaction was only observed for the commercial multicomponent mixture tested against H₂O₂. Further analysis was carried out to understand which compounds could be responsible for the antagonistic interaction. Seventeen single pure compounds present in all extracts were tested against AChE inhibition, most of them displaying weak or no activity. Only caffeine had a remarkable activity. Five different binary and quaternary mixture compositions were design to deepen the interaction between these compounds, revealing mainly phenolic acid-flavonoid, flavonoid-flavonoid and methylxanthine-flavonoid-phenolic acid antagonistic interactions. These results clearly show that, for the targets evaluated, there is no potentiation of the neuroprotective effect by combining S. baicalensis and G. biloba extracts.

Wogonin glucuronidation in liver and intestinal microsomes of humans, monkeys, dogs, rats, and mice

Wogonin, one of the flavonoids isolated from Scutellaria baicalensis, exhibits some beneficial bioactivities, including anti-inflammatory and anticancer effects, and is metabolized into glucuronide by UDP-glucuronosyltransferase (UGT) enzymes in humans. In the present study, wogonin glucuronidation was examined in the liver and intestinal microsomes of humans, monkeys, dogs, rats, and mice using a kinetic analysis.The kinetics of wogonin glucuronidation by liver microsomes followed the biphasic model in all species examined. CL_int values (x-intercept) based on v versus V/[S] plots were rats > humans ≈ monkeys > mice > dogs. The kinetics of intestinal microsomes fit the Michaelis-Menten model for humans, monkeys, rats, and mice and the substrate inhibition model for dogs. CL_int values were rats > monkeys > mice > dogs > humans. The tissue dependence of CL_int values was liver microsomes > intestinal microsomes for humans, dogs, and rats, and liver microsomes ≈ intestinal microsomes for monkeys and mice.These results demonstrated that the metabolic abilities of UGT enzymes toward wogonin in the liver and intestines markedly differ among humans, monkeys, dogs, rats, and mice, and suggest that species differences are closely associated with the biological effects of wogonin.

Huang-Lian Jie-Du decoction: a review on phytochemical, pharmacological and pharmacokinetic investigations

Huang-Lian Jie-Du decoction (HLJDD), a famous traditional Chinese prescription constituted by Rhizoma Coptidis, Radix Scutellariae, Cortex Phellodendri and Fructus Gradeniae, has notable characteristics of dissipating heat and detoxification, interfering with tumors, hepatic diseases, metabolic disorders, inflammatory or allergic processes, cerebral diseases and microbial infections. Based on the wide clinical applications, accumulating investigations about HLJDD focused on several aspects: (1) chemical analysis to explore the underlying substrates responsible for the therapeutic effects; (2) further determination of pharmacological actions and the possible mechanisms of the whole prescription and of those representative ingredients to provide scientific evidence for traditional clinical applications and to demonstrate the intriguing molecular targets for specific pathological processes; (3) pharmacokinetic feature studies of single or all components of HLJDD to reveal the chemical basis and synergistic actions contributing to the pharmacological and clinically therapeutic effects. In this review, we summarized the main achievements of phytochemical, pharmacological and pharmacokinetic profiles of HLJDD and its herbal or pharmacologically active chemicals, as well as our understanding which further reveals the significance of HLJDD clinically.

Pharmacokinetics of B-Ring Unsubstituted Flavones

B-ring unsubstituted flavones (of which the most widely known are chrysin, baicalein, wogonin, and oroxylin A) are 2-phenylchromen-4-one molecules of which the B-ring is devoid of any hydroxy, methoxy, or other substituent. They may be found naturally in a number of herbal products used for therapeutic purposes, and several have been designed by researchers and obtained in the laboratory. They have generated interest in the scientific community for their potential use in a variety of pathologies, and understanding their pharmacokinetics is important for a grasp of their optimal use. Based on a comprehensive survey of the relevant literature, this paper examines their absorption (with deglycosylation as a preliminary step) and their fate in the body, from metabolism to excretion. Differences among species (inter-individual) and within the same species (intra-individual) variability have been examined based on the available data, and finally, knowledge gaps and directions of future research are discussed.

Scutellaria baicalensis Georgi. (Lamiaceae): a review of its traditional uses, botany, phytochemistry, pharmacology and toxicology

OBJECTIVES

Scutellaria baicalensis Georgi. (Lamiaceae) is a plant of the genus Lamiaceae, and its root is the main part used as a medicine. In China, Scutellaria baicalensis is still an important traditional Chinese medicine with the functions of clearing away heat and dampness, purging fire and detoxification. This medicinal plant is widely distributed in China, Russia, Mongolia, North Korea and Japan. The purpose of this paper was to provide a systematic and comprehensive overview on the traditional usages, botany, phytochemistry, pharmacology, pharmacokinetics and toxicology of this plant. Furthermore, the possible development trends and perspectives for future research on this medicinal plant are also discussed.

KEY FINDINGS

So far, over 40 compounds have been isolated and identified from Scutellaria baicalensis, including flavonoids, terpenoids, volatile oils and polysaccharides. The compounds and extracts isolated from Scutellaria baicalensis exhibit a wide range of pharmacological activities, including the effects on the nervous system, effects on the immune system, liver protection, antitumour effects, antibacterial and antiviral effects, antioxidant effects and other pharmacological effects.

SUMMARY

As a traditional Chinese herbal medicine, Scutellaria baicalensis has shown significant effects on the treatment of various diseases, especially hepatitis, diarrhoea, vomiting and high blood pressure. Numerous traditional uses of Scutellaria baicalensis have been confirmed by current investigations. However, it is also necessary to further study the drug-forming properties and pharmacokinetics of the active constituents of Scutellaria baicalensis, as well as to establish quality control standards for different areas of Scutellaria baicalensis, and to carry out the research at the cellular and molecular levels.

Pharmacokinetic properties of wogonin and its herb-drug interactions with docetaxel in rats with mammary tumors

Docetaxel, frequently used for the treatment of breast cancer, is mainly metabolized via hepatic cytochrome P450 (CYP) 3A in humans and is also a substrate of P-glycoprotein (P-gp). Wogonin has been shown to be able to modulate the activities of CYPs and P-gp, and it could serve as an adjuvant chemotherapeutic agent. However, the impacts of co-administration of wogonin and docetaxel on their pharmacokinetics have not been studied because of a lack of an analytical method for their simultaneous measurement. In the present study, we established an HPLC-MS/MS method for simultaneous measurement of wogonin and docetaxel in rat plasma, and it was then utilized to explore the pharmacokinetics of wogonin and the herb-drug interactions between wogonin and docetaxel after their combined administration in rats with mammary tumors. The rats received 10, 20 and 40 mg/kg wogonin via oral administration, with or without docetaxel intravenously administered at 10 mg/kg, and the plasma concentrations of wogonin and docetaxel were measured using the established and validated HPLC-MS/MS method. The Cmax and AUC0-t of wogonin were proportionally increased in the dose range from 10 to 40 mg/kg, suggesting a linear pharmacokinetics of wogonin. Moreover, the Cmax and AUC0-t of docetaxel and the AUC0-t of wogonin were increased after co-administration (p < 0.05), indicating increased in vivo exposures of both wogonin and docetaxel, which might lead to an increase in not only therapeutic but also toxic effects. Thus the alterations of pharmacokinetics should be taken into consideration when wogonin and docetaxel are co-administered.

Pharmacokinetic Characteristics of Baicalin in Rats with 17α-ethynyl-estradiol-induced Intrahepatic Cholestasis

Baicalin is one of the main active ingredients of choleretic traditional Chinese medicine drug Radix Scutellariae. The aim of this study was to explore the pharmacokinetic characteristics of baicalin in rats with 17α-ethynylestradiol (EE)-induced intrahepatic cholestasis (IC) based on its choleretic effects. Firstly, rats were subcutaneously injected with EE solution (5 mg/kg, 0.25 mL/100 g) for 5 consecutive days to construct an IC model. Then the bile excretion rate, serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and total bile acid (TBA) and pathological changes of the liver were detected. Secondly, after successfully modeling, the rats were intragastrically given baicalin solution (200 mg/kg) (n=6). Blood samples were collected from the tail vein at different time points after intragastric administration. The protective effects of low- (50 mg/kg), medium- (100 mg/kg) and high-dose (200 mg/kg) baicalin on the liver in IC rats were evaluated. The content of baicalin in plasma was detected by liquid chromatography-mass spectrometry/mass spectrometry and pharmacokinetics parameters were calculated. Pharmacodynamic results showed that low-, medium- and high-dose baicalin all significantly increased the average excretion rate of bile (P<0.05), and significantly decreased serum levels of ALT, AST and ALP and TBA (P<0.05). Meanwhile, HE staining showed that baicalin significantly relieved EE-induced hepatocyte edema and necrosis. Pharmacokinetic results exhibited that the absorption of baicalin in both IC and normal control rats showed bimodal phenomenon. C_max, AU_(0-t) and AUC_(0-∞) of baicalin in IC rats were significantly higher than those of the normal control group (P<0.01). T_1/2 of plasma baicalin in the model group was significantly extended to (11.09±1.84) h, with clearance dropping to 61.78% of that of the normal control group (P<0.01). The above results suggested that baicalin had protective effects on the liver of IC rats, accompanied by significantly increased in vivo exposure, delayed in vivo clearance and markedly alterative pharmacokinetic characteristics. This study provides a theoretical basis for further development of baicalin as a feasible drug for treating IC.

Development of a new HPLC method for wogonin in rat plasma: Compatibility of standard and test samples

In the current paper, an HPLC/UV method was developed and validated for determination of wogonin in plasma. Considerable attention was paid to the preparation of standard samples and factors affecting drug distribution. A preparation procedure was devised to simulate the conditions the drug is expected to experience in vivo while pointing to the shortcomings of previously published methods. The method was validated according to the FDA regulations and showed to be highly efficient and capable of extracting the drug and IS from the plasma accurately and precisely within the specified range of 50-500 ng mL-1. Further, the standard sample preparation of this method can be used as a guideline for other methods, particularly when highly hydrophobic drugs with considerable protein binding are involved and could be valuable in the field of bioanalysis to improve the reliability of methods.

Oroxyloside A Overcomes Bone Marrow Microenvironment-Mediated Chronic Myelogenous Leukemia Resistance to Imatinib via Suppressing Hedgehog Pathway

Imatinib (IM), as first inhibitor of the oncogenic tyrosine kinase BCR-ABL, has been widely used to treat chronic myeloid leukemia (CML) for decades in clinic. However, resistance to IM usually occurs in CML patients. The bone marrow (BM), as the predominant microenvironment of CML, secretes an abundant amount of cytokines, which may contribute to drug resistance. In current study, we utilized in vitro K562 co-culture model with BM stroma to investigate IM resistance. As a result, co-culturing of K562 with BM stroma was sufficient to cause resistance to IM, which was accompanied with the activation of hedgehog (Hh) signaling pathway and upregulation of BCR-ABL as well as its downstream proteins like phosphorylated Akt, Bcl-xL and survivin, etc. On the other hand, oroxyloside A (OAG), a metabolite of oroxylin A from the root of Scutellaria baicalensis Georgi, which had low toxic effect on K562 cells, was able to sensitize K562 cells co-cultured with BM stroma to IM treatment in vitro and in vivo. We observed that OAG suppressed Hh pathway and subsequently nuclear translocation of GLI1, followed by downregulation of BCR-ABL and its downstream effectors, thus facilitating IM to induce apoptosis of K562 cells. Together, BM microenvironment rendered K562 cells drug resistance through activating Hh signaling, however, OAG could overcome IM resistance of CML cells through inhibiting Hh-BCR-ABL axis in vitro and in vivo.

Study on the Absorption Mechanism of Geniposide in the Chinese Formula Huang-Lian-Jie-Du-Tang in Rats

Huang-Lian-Jie-Du-Tang (HLJDT) is a classical recipe for relieving fever and toxicity for thousands of years in China. Geniposide is one of the main components in HLJDT. The present study was conducted in order to investigate the differences of absorption of geniposide after oral administration of geniposide alone and HLJDT in rats. Pharmacokinetic differences of geniposide following oral administrations of pure geniposide and HLJDT were investigated in vivo. The absorption of geniposide in pure compound and HLJDT was evaluated using intestinal perfusion and Caco-2 models. The in vivo and in vitro studies showed good relevance and consistent results. The co-occurring components in HLJDT were found to promote the absorption of geniposide from the pharmacokinetic study in vivo, intestinal perfusion, and Caco-2 model. Geniposide had better absorption in the duodenum and jejunum from the intestinal perfusion model, which was mainly absorbed by passive diffusion. Verapamil influenced the transportation of geniposide, while EDTA did not, demonstrating that geniposide might be the potential substance of P-glycoprotein in intestinal perfusion and Caco-2 models. The absorption of geniposide was studied systematically to guide the design of the oral dosage of geniposide and HLJDT in clinical therapy.

Two-Armed Activation of Bone Mineral Deposition by the Flavones Baicalin and Baicalein, Encapsulated in Polyphosphate Microparticles

In this study, we investigated the effect of the two flavonoids, baicalin (baicalein 7-O-[Formula: see text]- d-glucuronic acid) and its aglycone, baicalein (5,6,7-trihydroxyflavone), after encapsulation into amorphous calcium polyphosphate (Ca-polyP) microparticles on mineralization of primary human osteoblasts (phOSB). Both flavonoids, which come from root extracts of Scutellaria baicalensis Georgi, are used in Traditional Chinese Medicine, and are nontoxic in cells up to a concentration of 3[Formula: see text][Formula: see text]g/ml. The morphogenetically active, energy-rich Ca-polyP particles with a stoichiometric P:Ca ratio of 1:2 are degraded by cellular alkaline phosphatase (ALP) to ortho-phosphate used for bone hydroxyapatite formation. Here we show that the flavone-loaded Ca-polyP microparticles are readily taken up by phOSB, resulting in the accumulation of polyP around the nuclei and the formation of intracellular vesicles containing the ALP. In addition, we demonstrate that baicalin/baicalein causes a rise of the intracellular calcium [Ca[Formula: see text]]_i a level which markedly is augmented after encapsulation into Ca-polyP, through activation of the phospholipase C. Moreover, both flavones, either alone or associated with Ca-polyP microparticles, upregulate the expression of the osteoblast calcium efflux channel, the plasma membrane Ca[Formula: see text]-ATPase (PMCA), while the expression of ALP, which promotes bone mineralization, is induced by Ca-polyP and by the flavones only if present in the Ca-polyP-microparticle-associated form. As a result, the extent of bone mineralization is markedly enhanced. Based on the two-armed activating function, new applications of baicalin/baicalein as a component of nutriceuticals for osteoporosis prevention or bone implants can be envisaged.

Effects of baicalin on oral pharmacokinetics of caffeine in rats

Scutellaria baicalensis is one of the most widely used herbal medicines in East Asia. Because baicalein and baicalin are major components of this herb, it is important to understand the effects of these compounds on drug metabolizing enzymes, such as cytochrome P450 (CYP), for evaluating herb-drug interaction. The effects of baicalin and baicalein on activities of ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), benzyloxyresorufin O-debenzylase (BROD), p-nitrophenol hydroxylase and erythromycin N-demethylase were assessed in rat liver microsomes in the present study. In addition, the pharmacokinetics of caffeine and its three metabolites (i.e., paraxanthine, theobromine and theophylline) in baicalin-treated rats were compared with untreated control. As results, EROD, MROD and BROD activities were inhibited by both baicalin and baicalein. However, there were no significant differences in the pharmacokinetic parameters of oral caffeine and its three metabolites between control and baicalin-treated rats. When the plasma concentration of baicalin was determined, the maximum concentration of baicalin was below the estimated IC₅₀ values observed in vitro. In conclusion, baicalin had no effects on the pharmacokinetics of caffeine and its metabolites in vivo, following single oral administration in rats.

PF2405, standardized fraction of Scutellaria baicalensis, ameliorates colitis in vitro and in vivo

Standardized extraction procedures for herb are as important as their authentication to maintain their quality and ensure their safe use. We had prepared a standardized and purified Scutellaria baicalensis Georgi extract, PF2405, which was enriched with three major components, baicalein, oroxylin A and wogonin. In the present study, we investigated the potential anti-inflammatory effects of PF2405 in vitro and in two different experimental animal models of inflammatory bowel disease. Effect of PF2405 studied in tumor necrosis factor (TNF)-α-induced HT-29 cells in vitro. In vivo experimental colitis models were induced by administration of trinitrobenzene sulfonic acid (TNBS) or dextran sulfate sodium (DSS). PF2405 (50 μg/ml) decreased TNF-α-induced cyclooxygenase (COX)-2 expressions through inhibition of phosphorylation of c-Jun N-terminal kinases and p38 mitogen-activated protein kinase in HT-29 cells. Combination of baicalein (20 μg/ml), oroxylin A (8 μg/ml), and wogonin (2 μg/ml) markedly inhibits TNF-α-induced COX-2 expression when compared with individual components. PF2405 (25 mg/kg b.w.) treatment significantly reduced histopathological severity; suppressed expression of COX-2, TNF-α, and interleukin-1β in TNBS-induced mice. Moreover, PF2405 (25 mg/kg b.w.) has both potent preventive and therapeutic activities in DSS-induced colitis. Collectively, PF2405 shows prominent anti-inflammatory effect that can be used as a new therapeutic approach for intestinal inflammatory disorders.

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

ETHNOPHARMACOLOGICAL RELEVANCE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Novel pharmacokinetic studies of the Chinese formula Huang-Lian-Jie-Du-Tang in MCAO rats

Our previous studies showed that after oral administration of an Huang-Lian-Jie-Du-Tang (HLJDT) decoction, there is a higher concentration of the pure components, berberine, baicalin and gardenoside in the plasma of Middle cerebral artery occlusion (MCAO) rats than in sham-operated rats, The aim of the present study was to determine whether these components could be reliably measured in MCAO rat tissues. First, the plasma concentration-time profiles of berberine, palmatine, baicalin, baicalein and gardenoside were characterised in MCAO rats after oral administration of the aqueous extract of HLJDT. Subsequently, liver, lung and kidney tissues were obtained from sudden death MCAO rats in the absorption phase (0.25 h), the distribution phase (1.0 h) and the elimination phase (8.0 h) after administration of the HLJDT aqueous extract. An HPLC method was developed and validated for the determination of the distribution characteristics of berberine, palmatine, baicalin, baicalein and gardenoside simultaneously from the above-mentioned rat tissues. The results indicated that berberine, palmatine, baicalin and baicalein distributed rapidly and accumulated at high levels in the lung, while gardenoside distributed widely in the lung and the kidney. To the best of our knowledge, this is the first report to describe the distribution of the active ingredients derived from HLJDT in MCAO rat tissues. The tissue distribution results provide a biopharmaceutical basis for the design of the clinic application of HLJDT in cerebrovascular disease.

AKT serine/threonine protein kinase modulates baicalin-triggered autophagy in human bladder cancer T24 cells

Baicalin is one of the major compounds in the traditional Chinese medicinal herb from Scutellaria baicalensis Georgi. We investigated the molecular mechanisms of cell autophagy induced by baicalin in human bladder cancer T24 cells. Baicalin inhibited cell survival as shown by MTT assay and increased cell death by trypan blue exclusion assay in a concentration-dependent manner. Baicalin did not induce apoptotic cell death in T24 cells by TUNEL and caspase-3 activity assay. Baicalin induced the acidic vesicular organelle cell autophagy marker, manifested by acridine orange (AO) and monodansylcadaverine (MDC) staining and cleavage of microtubule-associated protein 1 light chain 3 (LC3). The protein expression levels of the Atg 5, Atg 7, Atg 12, Beclin-1 and LC3-II were upregulated in T24 cells after baicalin treatment. Inhibition of autophagy by 3-methyl-adenine (an inhibitor of class III phosphatidylinositol-3 kinase; 3-MA) reduced the cleavage of LC3 in T24 cells after baicalin treatment. Furthermore, protein expression levels of phospho-AKT (Ser473) and enzyme activity of AKT were downregulated in T24 cells after baicalin treatment. In conclusion, baicalin triggered cell autophagy through the AKT signaling pathway in T24 cells.

The effects of baicalein on canine osteosarcoma cell proliferation and death

Flavonoids are a group of modified triphenolic compounds from plants with medicinal properties. Baicalein, a specific flavone primarily isolated from plant roots (Scutellaria baicalensis), is commonly used in Eastern medicine for its anti-inflammatory and antineoplastic properties. Previous research shows greater efficacy for baicalein than most flavonoids; however, there has been little work examining their effects on sarcoma cells, let alone canine cells. Three canine osteosarcoma cell lines (HMPOS, D17 and OS 2.4) were treated with baicalein to examine cell viability, cell cycle kinetics, anchorage-independent growth and apoptosis. Results showed that osteosarcoma cells were sensitive to baicalein at concentrations from approximately 1 to 25 μM. Modest cell cycle changes were observed in one cell line. Baicalein was effective in inducing apoptosis and did not prevent doxorubicin cell proliferation inhibition in all the cell lines. The mechanism for induction of apoptosis has not been fully elucidated; however, changes in mitochondrial permeability supersede the apoptotic response.

Intestinal absorption and bioavailability of traditional Chinese medicines: a review of recent experimental progress and implication for quality control

Objectives

Experimental studies on the pharmacokinetics of traditional Chinese medicines (TCMs) have achieved great progress in recent years. This review aims to summarize the progress made on intestinal absorption and bioavailability of TCMs, and proposes the application of intestinal absorption assays as new tools for the quality and safety control of these medicines.

Key findings

Since only the absorbed constituents may produce possible therapeutic effect (except those that directly target the digestive tract), intestinal absorption is of utmost importance for the drug action of TCMs, which are usually taken orally. Meanwhile, complicated drug interactions may occur among the multiple ingredients in a herbal mixture. In this regard, the intestinal permeability assays not only provide useful pharmacokinetic data of TCMs, but have potential applications for quality and safety control. Moreover, knockout animals, 2/4/A1 in-vitro cell model and physiologically-based in-silico models based on the online TCM database can be quite useful for the prediction of absorption and bioavailability of TCMs.

Summary

A variety of in-vivo, in-vitro, in-situ and in-silico models for predicting the intestinal absorption and bioavailability can be applied to study the herbal interactions and screen appropriate biomarkers for the quality and safety control of TCMs.

A novel local recycling mechanism that enhances enteric bioavailability of flavonoids and prolongs their residence time in the gut

Recycling in the gastrointestinal tract is important for endogenous substances such as bile acids and for xenobiotics such as flavonoids. Although both enterohepatic and enteric recycling mechanisms are well recognized, no one has discussed the third recycling mechanism for glucuronides: local recycling. The intestinal absorption and metabolism of wogonin and wogonoside (wogonin-7-glucuronide) was characterized by using a four-site perfused rat intestinal model, and hydrolysis of wogonoside was measured in various enzyme preparations. In the perfusion model, the wogonoside and wogonin were interconverted in all four perfused segments. Absorption of wogonoside and conversion to its aglycon at the upper small intestine was inhibited in the presence of a glucuronidase inhibitor (saccharolactone) but was not inhibited by lactase phlorizin hydrolase (LPH) inhibitor gluconolactone or antibiotics. Further investigation indicated that hydrolysis of wogonoside in the blank intestinal perfusate was not correlated with bacterial counts. Kinetic studies indicated that K(m) values from blank duodenal and jejunal perfusate were essentially identical to the K(m) values from intestinal S9 fraction but were much higher (>2-fold) than those from the microbial enzyme extract. Lastly, jejunal perfusate and S9 fraction share the same optimal pH, which was different from those of fecal extract. In conclusion, local recycling of wogonin and wogonoside is the first demonstrated example that this novel mechanism is functional in the upper small intestine without significant contribution from bacteria β-glucuronidase.

Detection of baicalin metabolites baicalein and oroxylin-a in mouse pancreas and pancreatic xenografts

OBJECTIVES

Scutellaria baicalensis has been a subject of research interest due to its potential multiple therapeutic benefits. This study was to examine the distribution of baicalein, wogonin, oroxylin A and their glucuronide/sulfate-conjugated metabolites in plasma, colon, small intestine, lung, liver, pancreas, kidney, and prostate tissues and in pancreatic tumor in a xenograft animal model. In addition, we examined metabolic stability of baicalin in these tissues.

METHODS

A mouse xenograft model was prepared by injection of 3 × 10 human pancreatic cancer MiaPaCa-2 cells subcutaneously into nude mice. Mice were randomly allocated to control diet (AIN-76A) and 1% S. baicalensis diet (n = 8 per group) for 13 weeks. Levels of baicalein, wogonin, oroxylin A, and their conjugates in mouse tissues were measured by high-pressure liquid chromatography after enzymatic hydrolysis and then extraction.

RESULTS

A substantial amount of baicalin (34%-63%) was methylated to oroxylin A and its conjugates in various organs during absorption. Whereas plasma contained predominantly conjugates of baicalein, wogonin, and oroxylin A, both aglycones and conjugates were found in all other tissues investigated and in tumor.

CONCLUSIONS

Substantial accumulation of bioactive metabolites are found in target tissues, suggesting strong potential for S. baicalensis use as a preventive or adjuvant supplement for pancreatic cancer.

Pharmacological effects and pharmacokinetics properties of Radix Scutellariae and its bioactive flavones

Radix Scutellariae is the dried root of the medicinal plant Scutellariae baicalensis Georgi. It exhibits a variety of therapeutic effects and has a long history of application in traditional formulations as well as in modern herbal medications. It has been confirmed that flavonoids are the most abundant constituents and induce these therapeutic effects. Six flavones are proven to be the major bioactive flavones in Radix Scutellariae existing in the forms of aglycones (baicalein, wogonin, oroxylin A) and glycosides (baicalin, wogonoside, oroxylin A-7-glucuronide). All six flavones are pharmacologically active and show great potential in the treatment of inflammation, cancers and virus-related diseases. The current review covers the preparation of the herb Radix Scutellariae, quantification of its major bioactive ingredients, and pharmacological effects of the proposed six bioactive flavones. In addition, this review summarizes the pharmacokinetic profiles of the bioactive flavones reported so far that could be used for further improvement of their pharmacokinetic study. Moreover, due to abundant co-occurring bioactive components in Radix Scutellariae, our review further documents the pharmacokinetic interactions among them.

Identification and quantification of baicalein, wogonin, oroxylin A and their major glucuronide conjugated metabolites in rat plasma after oral administration of Radix scutellariae product

The current study aims to identify and quantify three flavones (baicalein, wogonin and oroxylin A) and their major metabolites (baicalin, wogonoside and oroxylin A-7-O-glucuronide) in rat plasma after oral administration of Radix scutellariae product. A simple HPLC/UV method has been developed to simultaneously determine the three flavones and their major metabolites in rat plasma. The chromatographic separation of the six analytes was achieved by a Thermo C(18) column with linear gradient elution of a mobile phase containing acetonitrile and 20mM sodium dihydrogen phosphate buffer (pH 4.6). All the tested analytes were detected by PDA detector at a wavelength of 320nm. The intra-day and inter-day precision for the current assay of the six analytes was within the range of -2.23% to 15.13% and -10.83% to 6.42%, respectively. All the studied analytes could be efficiently extracted from the rat plasma using HLB cartridge with extraction recoveries above 70% and were stable under different storage conditions. The developed assay method was successfully applied to the pharmacokinetic study of baicalin, wogonoside after oral administration of a commercially available Radix scutellariae containing capsule at a dose of 3.2g/kg to Sprague-Dawley rats. In addition to wogonoside, a new metabolite of wogonin has been identified using LC/MS/MS for the first time.

Use of isoform-specific UGT metabolism to determine and describe rates and profiles of glucuronidation of wogonin and oroxylin A by human liver and intestinal microsomes

PURPOSES

Glucuronidation via UDP-glucuronosyltransferases (or UGTs) is a major metabolic pathway. The purposes of this study are to determine the UGT-isoform-specific metabolic fingerprint (or GSMF) of wogonin and oroxylin A, and to use isoform-specific metabolism rates and kinetics to determine and describe their glucuronidation behaviors in tissue microsomes.

METHODS

In vitro glucuronidation rates and profiles were measured using expressed UGTs and human intestinal and liver microsomes.

RESULTS

GSMF experiments indicated that both flavonoids were metabolized mainly by UGT1As, with major contributions from UGT1A3 and UGT1A7-1A10. Isoform-specific metabolism showed that kinetic profiles obtained using expressed UGT1A3 and UGT1A7-1A10 could fit to known kinetic models. Glucuronidation of both flavonoids in human intestinal and liver microsomes followed simple Michaelis-Menten kinetics. A comparison of the kinetic parameters and profiles suggests that UGT1A9 is likely the main isoform responsible for liver metabolism. In contrast, a combination of UGT1As with a major contribution from UGT1A10 contributed to their intestinal metabolism. Correlation studies clearly showed that UGT isoform-specific metabolism could describe their metabolism rates and profiles in human liver and intestinal microsomes.

CONCLUSION

GSMF and isoform-specific metabolism profiles can determine and describe glucuronidation rates and profiles in human tissue microsomes.