In vitro assessment of the inhibitory effect of goreisan extract and its ingredients on the P-glycoprotein drug transporter and cytochrome P-450 metabolic enzymes.

Kampo medicines are widely used in Japan; however, their potential to cause drug interactions still remains unclear and needs to be further investigated. The effects of goreisan on the P-glycoprotein (P-gp) and the cytochrome P-450 (CYP), which are associated with drug interactions, were investigated.The inhibitory effect of goreisan extract on P-gp was evaluated using a Caco-2 cell permeability assay. The results indicated that it inhibited P-gp function in a concentration-dependent manner.The inhibitory effect of three goreisan ingredients (alisol A, tumulosic acid, and (E)-cinnamic acid) on seven CYP isoforms was evaluated using human liver microsomes (HLM). Of these, tumulosic acid and (E)-cinnamic acid exhibited less than 16% inhibition at concentrations of 10 µmol/L against any of the CYP isoforms tested. Alisol A inhibited only CYP3A but showed no inhibitory effect with pre-incubation.These results indicate that goreisan extract has inhibitory activity against P-gp and that alisol A, a goreisan ingredient, exhibits an inhibitory effect on CYP3A. However, these are thought to be minor or negligible in vivo. Overall, these findings will be useful to evaluate possible drug interactions and provide support for the interpretation of future clinical drug-drug interaction studies involving goreisan.

Gosha-jinki-Gan (GJG) shows anti-aging effects through suppression of TNF-α production by Chikusetsusaponin V.

Frailty develops due to multiple factors, such as sarcopenia, chronic pain, and dementia. Go-sha-jinki-Gan (GJG) is a traditional Japanese herbal medicine used for age-related symptoms. We have reported that GJG improved sarcopenia, chronic pain, and central nervous system function through suppression of tumor necrosis factor-alpha (TNF-α) production. In the present study, GJG was found to reduce the production of TNF-α in the soleus muscle of senescence-accelerated mice at 12 weeks and 36 weeks. GJG did not change the differentiation of C2C12 cells with 2% horse serum. GJG significantly decreased the expression of Muscle atrophy F-box protein (MAFbx) induced by TNF-α in C2C12 cells on real-time PCR. TNF-α significantly decreased the expression of PGC-1α and negated the enhancing effect of GJG for the expression of PGC-1α on digital PCR. Examining 20 chemical compounds derived from GJG, cinnamaldehyde from cinnamon bark and Chikusetsusaponin V (CsV) from Achyrantes Root dose-dependently decreased the production of TNF-⍺ in RAW264.7 cells stimulated by LPS. CsV inhibited the nuclear translocation of nuclear factor-kappa B (NF-κB) p65 in RAW264.7 cells. CsV showed low permeability using Caco-2 cells. However, the plasma concentration of CsV was detected from 30 min to 6 h and peaked at 1 h in the CD1 (ICR) mice after a single dose of GJG. In 8-week-old SAMP8 mice fed 4% (w/w) GJG from one week to four weeks, the plasma CsV concentration ranged from 0.0500 to 10.0 ng/mL. The evidence that CsV plays an important role in various anti-aging effects of GJG via suppression of TNF-⍺ expression is presented.

Use of a Caco-2 permeability assay to evaluate the effects of several Kampo medicines on the drug transporter P-glycoprotein.

In modern medical care in which Kampo and Western drugs are often combined, it is extremely important to clarify drug-drug interaction (DDI) to ensure safety and efficacy. However, there is little evidence of DDI in Kampo medicines. Therefore, as part of our studies to clarify the DDI risk for Kampo medicines, we evaluated the effects of five Kampo medicines [yokukansan (YKS), rikkunshito (RKT), shakuyakukanzoto (SKT), hangeshashinto (HST), and goshajinkigan (GJG)] that are widely used in Japan, on drug transporter P-glycoprotein (P-gp) using a Caco-2 permeability assay. These Kampo medicines inhibited the P-gp transport of digoxin through a Caco-2 cell monolayer. The IC50 values were 1.94-10.80 mg/ml. Of the five Kampo medicines, YKS showed the strongest inhibition (IC50 = 1.94 mg/ml), which was attributed to Uncariae Uncis Cum Ramulus. Unfortunately, we could not find the active ingredients responsible for its action. Finally, the Igut/IC50 values for the five Kampo medicines were calculated, and the DDI risk was objectively evaluated according to the criteria in the DDI guidance issued by the Japanese Ministry of Health, Labor, and Welfare and the US Food and Drug Administration. The Igut/IC50 values for the five Kampo medicines were ≤3.4. As these values were <10, they were evaluated as having a weak P-gp inhibitory effect that does not require further verification in humans, suggesting that the DDI risk due to P-gp inhibition for these Kampo medicines is low. The results should provide useful clinical information on the safety and efficacy of the combined use of Kampo and Western medicines.

Ignavine: a novel allosteric modulator of the µ opioid receptor.

Processed Aconiti tuber (PAT) is used to treat pain associated with various disorders. Although it has been demonstrated that the κ opioid receptor (KOR) signaling pathway is a mediator of the analgesic effect of PAT, active components affecting opioid signaling have not yet been identified. In this study, we explored candidate components of PAT by pharmacokinetic analysis and identified ignavine, which is a different structure from aconitine alkaloids. A receptor binding assay of opioid receptors showed that ignavine specifically binds the µ opioid receptor (MOR), not the KOR. Receptor internalization assay in MOR-expressing cell lines revealed that ignavine augmented the responses produced by D-Ala(2)-N-Me-Phe(4)-Gly-ol(5)-enkephalin (DAMGO), a representative MOR agonist, at a low concentration and inhibited it at a higher concentration. Ignavine also exerted positive modulatory activity for DAMGO, endomorphin-1 and morphine in cAMP assay. Additionally, ignavine alone showed an analgesic effect in vivo. In silico simulation analysis suggested that ignavine would induce a unique structural change distinguished from those induced by a representative MOR agonist and antagonist. These data collectively suggest the possibility that ignavine could be a novel allosteric modulator of the MOR. The present results may open the way for the development of a novel pain management strategy.

CRF receptor 1 antagonism and brain distribution of active components contribute to the ameliorative effect of rikkunshito on stress-induced anorexia.

Rikkunshito (RKT), a Kampo medicine, has been reported to show an ameliorative effect on sustained hypophagia after novelty stress exposure in aged mice through serotonin 2C receptor (5-HT2CR) antagonism. We aimed to determine (1) whether the activation of anorexigenic neurons, corticotropin-releasing factor (CRF), and pro-opiomelanocortin (POMC) neurons, is involved in the initiation of hypophagia induced by novelty stress in aged mice; (2) whether the ameliorative effect of RKT is associated with CRF and POMC neurons and downstream signal transduction; and (3) the plasma and brain distribution of the active components of RKT. The administration of RKT or 5-HT2CR, CRF receptor 1 (CRFR1), and melanocortin-4 receptor antagonists significantly restored the decreased food intake observed in aged male C57BL/6 mice in the early stage after novelty stress exposure. Seven components of RKT exhibited antagonistic activity against CRFR1. Hesperetin and isoliquiritigenin, which showed antagonistic effects against both CRFR1 and 5-HT2CR, were distributed in the plasma and brain of male Sprague-Dawley rats after a single oral administration of RKT. In conclusion, the ameliorative effect of RKT in this model is assumed to be at least partly due to brain-distributed active components possessing 5-HT2CR and CRFR1 antagonistic activities.

Preventive effect of oral goshajinkigan on chronic oxaliplatin-induced hypoesthesia in rats.

Oxaliplatin, a widely used chemotherapeutic agent, induces peripheral neuropathy that manifests itself as two distinct phases: acute cold hyperesthesia and chronic peripheral hypoesthesia/dysesthesia. The latter is a serious dose-limiting side effect that can often lead to withdrawal of treatment. We have developed a rat model expressing both phases and used the model to investigate the action of goshajinkigan (GJG), a traditional Japanese herbal medicine, which was reported to ameliorate oxaliplatin-induced neuropathy in a placebo-controlled double-blind randomized phase II study. In this study, neuropathy was induced by injection of oxaliplatin twice weekly for 8 wks. The maximum level of cold hyperesthesia was observed at 4 wks with heat hypoesthesia developing later. Microscopy studies revealed atrophy of axons of myelinated sciatic nerve fibers in oxaliplatin-treated rats at 8 wks. Co-administration of GJG ameliorated both abnormal sensations as well as histological damage to the sciatic nerve. A pharmacokinetic study revealed numerous neuroprotective components of GJG that are rapidly absorbed into the blood. GJG and some of its components attenuated the generation of oxaliplatin-induced reactive oxygen species, which is a possible mechanism of oxaliplatin-induced neurotoxicity. The present study provides a useful animal model for oxaliplatin-induced neurotoxicity as well as a promising prophylactic agent.

Plasma Pharmacokinetics of Polyphenols in a Traditional Japanese Medicine, Jumihaidokuto, Which Suppresses Propionibacterium acnes-Induced Dermatitis in Rats.

Most orally administered polyphenols are metabolized, with very little absorbed as aglycones and/or unchanged forms. Metabolic and pharmacokinetic studies are therefore necessary to understand the pharmacological mechanisms of polyphenols. Jumihaidokuto (JHT), a traditional Japanese medicine, has been used for treatment of skin diseases including inflammatory acne. Because JHT contains various types of bioactive polyphenols, our aim was to clarify the metabolism and pharmacokinetics of the polyphenols in JHT and identify active metabolites contributing to its antidermatitis effects. Orally administered JHT inhibited the increase in ear thickness in rats induced by intradermal injection of Propionibacterium acnes. Quantification by LC-MS/MS indicated that JHT contains various types of flavonoids and is also rich in hydrolysable tannins, such as 1,2,3,4,6-penta-O-galloyl glucose. Pharmacokinetic and antioxidant analyses showed that some flavonoid conjugates, such as genistein 7-O-glucuronide and liquiritigenin 7-O-glucuronide, appeared in rat plasma and had an activity to inhibit hydrogen peroxide-dependent oxidation. Furthermore, 4-O-methylgallic acid, a metabolite of Gallic acid, appeared in rat plasma and inhibited the nitric oxide reaction. JHT has numerous polyphenols; it inhibited dermatitis probably via the antioxidant effect of its metabolites. Our study is beneficial for understanding in vivo actions of orally administered polyphenol drugs.

Inhibition of Rat 5α-Reductase Activity and Testosterone-Induced Sebum Synthesis in Hamster Sebocytes by an Extract of Quercus acutissima Cortex.

Objective. Bokusoku (BK) is an extract from the Quercus cortex used in folk medicine for treatment of skin disorders and convergence, and is present in jumihaidokuto, a traditional Japanese medicine that is prescribed for purulent skin diseases like acne vulgaris. The excess of sebum production induced by androgen is involved in the development of acne. Our aim is to examine whether BK and its constituents inhibit testosterone metabolism and testosterone-induced sebum synthesis. Methods. Measurements of 5α-reductase activity and lipogenesis were performed using rat liver microsomes and hamster sebocytes, respectively. Results. BK dose-dependently reduced the conversion of testosterone to a more active androgen, dihydrotestosterone in a 5α-reductase enzymatic reaction. Twenty polyphenols in BK categorized as gallotannin, ellagitannin, and flavonoid were identified by LC-MS/MS. Nine polyphenols with gallate group, tetragalloyl glucose, pentagalloyl glucose, eugeniin, 1-desgalloyl eugeniin, casuarinin, castalagin, stenophyllanin C, (-)-epicatechin gallate, and (-)-epigallocatechin gallate, inhibited testosterone metabolism. In particular, pentagalloyl glucose showed the strongest activity. BK and pentagalloyl glucose suppressed testosterone-induced lipogenesis, whereas they weakly inhibited the lipogenic action of insulin. Conclusions. BK inhibited androgen-related pathogenesis of acne, testosterone conversion, and sebum synthesis, partially through 5α-reductase inhibition, and has potential to be a useful agent in the therapeutic strategy of acne.

Multitargeted effects of hangeshashinto for treatment of chemotherapy-induced oral mucositis on inducible prostaglandin E2 production in human oral keratinocytes.

OBJECTIVE: Chemotherapy-induced oral mucositis (COM) is characterized by painful inflammation with prolonged damage that involves the pathological pain-evoking prostaglandin E2 (PGE2). We previously found that gargling with hangeshashinto (HST), a traditional Japanese medicine, was effective for the treatment of COM. However, little is known regarding the mechanisms. Our aim was to identify the active ingredients and clarify the characteristic effects of HST on the PGE2 system. METHODS: Prostanoids produced by human oral keratinocytes (HOK) stimulated with IL-1ß were measured by enzyme immunoassay. Active ingredients that regulate PGE2 production were identified and quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and a culture system of HOK cells. RESULTS: Inducible PGE2, PGD2, and PGF2α, metabolites of cyclooxygenase (COX) pathways, were reduced by HST (10-300 µg/mL) without inducing cytotoxicity. The active ingredients of HST were quantified by LC-MS/MS, and [6]-shogaol, [6]-gingerol, wogonin, baicalein, baicalin, and berberine were shown to reduce PGE2 production. A mixture of these 6 ingredients at concentrations equal to 300 µg/mL of HST strongly suppressed PGE2 production to the same level as HST. [6]-Shogaol and [6]-gingerol did not decrease COX-2 mRNA expression and mostly inhibited PGE2 metabolic activity in an assay using intact HOK cells, suggesting that they regulate PGE2 synthesis at the posttranscriptional level. Wogonin, baicalin, and berberine inhibited expression of COX-2 mRNA without affecting PGE2 metabolic activity. Moreover, wogonin, but not [6]-shogaol, suppressed phosphorylation of mitogen-activated protein kinases (p38s and JNKs). CONCLUSIONS: These lines show that HST includes several PGE2-regulating ingredients that have different mechanisms and can function as a multicomponent and multitarget agent for treatment of COM, indicating that HST may be beneficial in a new medical strategy for COM treatment.

Pharmacokinetics of [6]-shogaol, a pungent ingredient of Zingiber officinale Roscoe (Part I).

To investigate the pharmacokinetics of [6]-shogaol, a pungent ingredient of Zingiber officinale Roscoe, the pharmacokinetic parameters were determined by using (14)C-[6]-shogaol (labeled compound) and [6]-shogaol (non-labeled compound). When the labeled compound was orally administered to rats, the maximum plasma concentration (C (max)) and the area under the curve (AUC) of plasma radioactivity concentration increased in a dose-dependent manner. When the labeled compound was orally administered at a dose of 10 mg/kg, 20.0 + or - 1.8% of the radioactivity administered was excreted into urine, 64.0 + or - 12.9% into feces, and 0.2 + or - 0.1% into breath. Thus, more of the radioactivity was excreted into feces than into urine, and almost no radioactivity was excreted into breath. Furthermore, when the labeled compound was orally administered at a dose of 10 mg/kg, cumulative biliary radioactivity excretion over 48 h was 78.5 + or - 4.5% of the radioactivity administered, and cumulative urinary radioactivity excretion over 48 h was 11.8 + or - 2.7%, showing that about 90% of the dose administered orally was absorbed from the digestive tract and most of the fecal excretion was via biliary excretion. On the other hand, when the non-labeled compound [6]-shogaol was orally administered, the plasma concentration and biliary excretion of the unchanged form were extremely low. When these results are combined with those obtained with the labeled compound, it would suggest that [6]-shogaol is mostly metabolized in the body and excreted as metabolites.

The influence of the sennosides on absorption of glycyrrhetic acid in rats.

In the course of our clinical studies of Kampo medicine (traditional Japanese medicines), we observed the pharmacokinetic interactions between two herbs. When Onpito (TJ-8117, Kampo medicine) containing licorice and rhubarb was administered orally to human subjects, we observed that the AUC(0-lim) and Cmax of glycyrrhetic acid (GA) in plasma were lower than those treated with other Kampo medicines containing licorice. In this study, we demonstrate the pharmacokinetic interactions of GA derived from glycyrrhizinic acid (GL) in licorice and anthraquinones derived from rhubarb. To our knowledge, this is the first report to investigate the pharmacokinetic interactions between two herbs. When GL was orally co-administrated to rats with a non-effective dose of sennoside A having purgative activity, the AUC(0-lim) and Cmax of GA decreased. In addition, sennoside A did not affect the metabolism of GL by the intestinal bacteria in vitro. In the examination using an in situ loop of rat colon, the remaining ratio of GA rose drastically by the co-administration of sennoside A, sennidin A and rhein. Observed inhibition activity of these anthraquinones on GA absorption depended on the concentration of the components added. The maximum inhibition ratio was approximately 75% by rhein, 60% by sennoside A and 25% by sennidin A. We conclude that the decrease of the pharmacokinetic parameters of GA in human plasma observed in the clinical study of TJ-8117 is attributable to an interactive action of absorption from the intestinal tract by anthraquinones contained in or derived from rhubarb.

Involvement of ABC transporters in chemosensitivity of human renal cell carcinoma, and regulation of MRP2 expression by conjugated bilirubin.

In this study, the involvement of ATP-binding cassette (ABC) transporters in in vitro chemosensitivity of surgically removed human renal cell carcinomas was investigated. The relative expression levels of transporter mRNAs in the renal tumors from 13 patients were similar to those in the surrounding normal kidney tissues. Five renal cell carcinomas cultured successfully in vitro for 14 days showed significantly decreased expression of multi-drug resistance-associated proteins 2 and 6 (MRP2 and MRP6) mRNAs. In vitro chemosensitivity testing of the same specimens using the collagen-gel matrix assay indicated that some anticancer drugs were effective, especially cisplatin, which is an MRP2 substrate. MRP2 mRNA expression in renal carcinoma was significantly increased when cells were cultured in the presence of conjugated bilirubin. In an established renal proximal tubule epithelial cell line (RPTEC), conjugated bilirubin increased MRP2 expression at the mRNA and protein levels, and decreased the cisplatin sensitivity of the cells. These results indicate that MRP2 expression in renal cell carcinoma may be regulated by conjugated bilirubin in the body and decreased during in vitro culture. Thus, the effectiveness of anticancer drugs selected on the basis of in vitro chemosensitivity testing of clinical cancers may be overestimated.

Cremophor EL releases cyclosporin A adsorbed on blood cells and blood vessels, and increases apparent plasma concentration of cyclosporin A.

We examined the influence of cremophor EL (crEL) on the disposition kinetics of CyA in rats. A dose of 10mg/kg of CyA in a volume of 750 microL containing 4.3, 16 or 30% concentration of crEL was intravenously administered over 1 min to rats. The values of distribution volume at the steady-state (Vd(ss)) and total clearance (CL(tot)) of CyA in the presence of increasing amounts of crEL were decreased to about 1/3-1/5 of those with 4.3% crEL, in a crEL concentration-dependent manner. The values of blood to plasma concentration ratio (RBP) and the apparent tissue to plasma concentration ratio (K(p,app)) of CyA with 30% crEL were both only about 1/2 of those of CyA with 4.3% crEL. Next, rats were intravenously given 30% crEL solution at 30 min after an intravenous administration of CyA (10 mg/kg) with 4.3% crEL. Subsequently, the blood and plasma concentrations of CyA rose significantly to 2.4 and 4.7 times those seen when i.v. 30% crEL was not given, respectively. In an in vitro study, we found that the uptake of CyA by red blood cells is inhibited by crEL, and that CyA adsorbed on the inner surface of blood vessels after the administration of CyA is released by crEL. The disposition kinetics of CyA is altered by i.v. administration in combination with the surfactant vehicle crEL, in a crEL concentration-dependent manner.