The transport mechanism of monocarboxylate transporter on spinosin in Caco-2 cells.

OBJECTIVES: The aim of this study was to determine the uptake mechanism of spinosin (SPI) by the monocarboxylic acid transporters (MCTs) in Caco-2 cells. METHODS: The Caco-2 cells were pretreated with various monocarboxylic acids, and the uptake of spinosin from Caco-2 cells was measured by High Performance Liquid Chromatography (HPLC). KEY FINDINGS: Preloading of various monocarboxylic acids enhanced the uptake of SPI, especially salicylic acid (a substrate of MCTs) had a 23.4 times increase in SPI uptake, indicating that the monocarboxylic acid transporters had an efflux effect on SPI uptake and salicylic acid had a strong inhibition on SPI efflux in Caco-2 cells. At the same time, the uptake of SPI through Caco-2 cells was Na(+)- and temperature-dependent, pretreatment without Na(+) significantly increased the uptake of SPI by 1.85 times and incubated at low temperature (4 °C) SPI uptake increased 20% than that of 37 °C. Furthermore, SPI was transported mainly via a carrier-mediated transport: [Vmax = 5.364 µg/mg protein, Km = 657.0 µg/mL]. CONCLUSION: The uptake of spinosin (SPI) in Caco-2 cells was mainly regulated by the monocarboxylic acid transporters along with Salicylic acid.

[Clinical application characteristics of Danggui-Chuanxiong herb pair in Chinese medicines on basis of real-world].

To analyze the clinical application characteristics of Danggui-Chuanxiong(DG-CX) herb pair in Chinese medicines on basis of real-world, and provide reference for explaining the inherent compatibility regularity and the relationship between clinical applications and disease species. From April 1, 2014 to June 30, 2014, a total of 8 792 prescriptions with both "DG"and "CX" in a large third-grade class-A traditional Chinese medicine(TCM) hospital were selected to establish the database for analyzing the ratio, dosage, and corresponding disease species of DG-CX herb pair. The results showed that, "DG-CX" with ratio "1∶1" had the highest frequency in clinical application(42.4%); the dosage was mainly of 15 g for both DG and CX; the disease species were mainly of encephalopathy and pulmonary diseases. "DG-CX" herb pairs with a ratio greater than "1∶1" accounted for 33.3% of all the prescriptions, and the ratio "3∶2" appeared to be most frequent among them; the dosage was mainly of 15 g for DG and and 10 g for CX; the disease species were mainly of encephalopathy diseases. "DG-CX" herb pairs with a ratio less than "1∶1" accounted for 24.3% of all the prescriptions, and the ratio "2∶3" appeared to be most frequent among them; the dosage was mainly of 10 g for DG and 15 g for CX; the disease species were mainly of encephalopathy diseases. Statistical method was applied to study the compatibility and application characteristics of Chinese herb pairs in clinical prescriptions, effectively discover the medication regularity, provide theoretical basis for clinical herbal prescriptions and provide scientific guidance and reliable data for modern research of Chinese herb pairs.

Evaluation of impact of Herba Erigerontis injection, a Chinese herbal prescription, on rat hepatic cytochrome P450 enzymes by cocktail probe drugs.

ETHNOPHARMACOLOGICAL RELEVANCE: Herba Erigerontis injection (HEI), one of the most popular herbal prescription in China, is made from the aqueous extracts of Erigeron breviscapus whole plant. Now HEI is widely used for the treatment of cardiovascular diseases and cerebrovascular diseases such as coronary heart disease, anginapectoris and paralysis. AIM OF THE STUDY: The purpose of this study was to investigate the in vivo effect of HEI on rat cytochrome P450 enzymes (CYP1A2, CYP2C11, CYP2D4, CYP2E1 and CYP3A2) to assess its safety through its potential to interact with co-administered drugs. MATERIALS AND METHODS: Rats were randomly divided into five groups. Rats were intravenous administrated with HEI via the caudal vein at the dosage of 1.8ml/kg or 7.2ml/kg once daily for consecutive 3 days or 14 days. On the fourth or the fifteenth day, a cocktail solution at a dose of 5ml/kg, which contained caffeine (2.5mg/kg), tolbutamide (2.5mg/kg), chlorzoxazone (5mg/kg), midazolam (5mg/kg) and metoprolol (10mg/kg), was injected via the lingual vein to all rats. Then 0.8ml blood samples were collected at a set of time-points. The plasma concentrations of probe drugs were simultaneously determined by HPLC. Pharmacokinetic parameters simulated by DAS software were used for the evaluation of HEI on the activities of rat CYP1A2, CYP2C11, CYP2D4, CYP2E1 and CYP3A2 enzymes. ANOVA and Dunnett's test was used for data analysis. RESULTS: There were no significant influence of pharmacokinetic parameters of caffeine, tolbutamide and chlorzoxazone in HEI pretreated rats. But many pharmacokinetic parameters of metoprolol and midazolam in HEI pretreated rats were affected significantly (P<0.05), which indicated that metabolism of metoprolol and midazolam in these treatment groups was evidently slowed down. CONCLUSIONS: The results from the present in vivo study suggested that HEI showed no effects on rat CYP1A2, CYP2C11 and CYP2E1, however, it demonstrated potential inhibitory effects on rat CYP2D4 and CYP3A2. Therefore, caution is needed when HEI is co-administered with drugs metabolized by human CYP2D6 or CYP3A4 in clinic, which may result in increased concentrations of these drugs and relevant herb-drug interactions.

Inhibitory effects of limonin on six human cytochrome P450 enzymes and P-glycoprotein in vitro.

Among the various possible causes for drug interactions, pharmacokinetic factors such as inhibition of drug-metabolizing enzymes and transporters, especially cytochrome P450 (CYP) isoenzymes and P-glycoprotein (P-gp), are regarded as the most frequent and clinically important. Limonin is a widely used dietary supplement and one of the most prevalent citrus limonoids, which are known to have inhibitory effects on CYPs and P-gp. In this study, the in vitro inhibitory effects of limonin on the major human CYP isoenzymes (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4) activities in human liver microsomes were examined using liquid chromatography-tandem mass spectrometry. The inhibitory effects of limonin on P-gp activity in a human metastatic malignant melanoma cell line WM-266-4 were examined using a calcein-AM fluorometry screening assay. It demonstrates that limonin has negligible inhibitory effects on human CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and P-gp. However, potent inhibition of CYP3A4 by limonin is observed with IC50 values of 6.20 µM (CYP3A4/testosterone) and 19.10 µM (CYP3A4/midazolam). This finding has important implications with regard to food-drug interactions between limonin and several narrow therapeutic index drugs that are metabolized by CYP3A4.

In vitro inhibition of Huanglian [Rhizoma coptidis (L.)] and its six active alkaloids on six cytochrome P450 isoforms in human liver microsomes.

Huanglian (Rhizoma Coptidis) as a popular herb has been used for the treatment of various diseases such as diarrhea, eye inflammation and women's abdominal ailments. Alkaloids are considered to be responsible for its pharmacological effects. In this investigation, Huanglian and its six alkaloids (coptisine, epiberberine, berberine, jateorrhizine, palmatine and magnoflorine) were systematically evaluated for their inhibition of six cytochrome P450 isoforms (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) in human liver microsomes by the LC-MS/MS method. Huanglian showed the strongest inhibition of CYP2D6, followed by CYP1A2 and CYP3A4_T. The IC50 values were 5.8 µg/mL, 36.8 µg/mL and 59.2 µg/mL, respectively. Of the constituents tested, coptisine and epiberberine showed strong inhibition of CYP2D6 with IC50 values of 4.4 µM and 7.7 µM; berberine, jateorrhizine and palmatine showed weak inhibition of CYP2D6 with IC50 values of 45.5 µM, 49.4 µM and 92.6 µM, respectively; jateorrhizine showed moderate inhibition of CYP3A4_T with an IC50 value of 13.3 µM; coptisine showed weak inhibition of CYP1A2 with an IC50 value of 37.3 µM. In addition, activation was observed in coptisine/CYP2C9 and palmatine/CYP2C9/CYP2C19. Other CYP450 isoforms were not affected markedly by the six alkaloids. In conclusion, Huanglian showed in vitro inhibition of CYP2D6, the inhibition might be contributed mostly by protoberberine alkaloids, especially coptisine and epiberberine. Herb-drug interactions may occur through the CYP2D6 inhibition.