Physiologically Based Pharmacokinetic Modeling of Bergamottin and 6,7-Dihydroxybergamottin to Describe CYP3A4 Mediated Grapefruit-Drug Interactions.

Grapefruit is a moderate to strong inactivator of CYP3A4, which metabolizes up to 50% of marketed drugs. The inhibitory effect is mainly attributed to furanocoumarins present in the fruit, irreversibly inhibiting preferably intestinal CYP3A4 as suicide inhibitors. Effects on CYP3A4 victim drugs can still be measured up to 24 hours after grapefruit juice (GFJ) consumption. The current study aimed to establish a physiologically-based pharmacokinetic (PBPK) grapefruit-drug interaction model by modeling the relevant CYP3A4 inhibiting ingredients of the fruit to simulate and predict the effect of GFJ consumption on plasma concentration-time profiles of various CYP3A4 victim drugs. The grapefruit model was developed in PK-Sim and coupled with previously developed PBPK models of CYP3A4 substrates that were publicly available and already evaluated for CYP3A4-mediated drug-drug interactions. Overall, 43 clinical studies were used for model development. Models of bergamottin (BGT) and 6,7-dihydroxybergamottin (DHB) as relevant active ingredients in GFJ were established. Both models include: (i) CYP3A4 inactivation informed by in vitro parameters, (ii) a CYP3A4 mediated clearance estimated during model development, as well as (iii) passive glomerular filtration. The final model successfully describes interactions of GFJ ingredients with 10 different CYP3A4 victim drugs, simulating the effect of the CYP3A4 inactivation on the victims' pharmacokinetics as well as their main metabolites. Furthermore, the model sufficiently captures the time-dependent effect of CYP3A4 inactivation as well as the effect of grapefruit ingestion on intestinal and hepatic CYP3A4 concentrations.

Imperatorin Influences Depressive-like Behaviors: A Preclinical Study on Behavioral and Neurochemical Sex Differences.

Imperatorin, a naturally derived furanocoumarin, exerts promising neuropharmacological properties. Therefore, it might be applicable in the treatment of brain diseases such as depression. In the present project, we aimed to investigate the sex-dependent effects of imperatorin (1, 5, and 10 mg/kg) on behavior and neurochemistry associated with antidepressant effects. The depressive-like behaviors of male and female Swiss mice were investigated in a forced swim test (FST). Subsequently, High-Performance Liquid Chromatography (HPLC) was used to evaluate the level of serotonin, its metabolite, 5-HIAA, and noradrenaline, in mouse brains. The study revealed that only males responded to imperatorin (1 and 5 mg/kg) treatment and caused an antidepressant effect, such as with respect to depressive-like behaviors, lowering immobility time and increasing immobility latency. The HPLC analysis demonstrated that serotonin levels in the prefrontal cortex of females decreased with the middle dose of imperatorin (5 mg/kg), while in the male prefrontal cortex, the lower dose (1 mg/kg) boosted serotonin levels. There were no evident changes observed with respect to noradrenaline and serotonin metabolite levels in the male hippocampus. To conclude, we propose that imperatorin has antidepressant potential, seemingly only in males, influencing brain serotonin level, but the direct mechanism of action requires further investigation.

Study on pharmacokinetics of eight active compounds from Bufei-Huoxue Capsule based on UHPLC-MS/MS.

Bufei-Huoxue Capsule (BFHX) was applied to treat chronic obstructive pulmonary disease (COPD) in China. It is composed of Astragali Radix, Paeoniae Radix Rubra, and Psoralea Fructus. A sensitive and reliable ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) method was developed and validated to quantify the eight main bioactive compounds (psoralen, isopsoralen, neobabaisoflavone, corylin, bavachin, astragaloside IV, ononin and formononetin) in rat plasma after oral administration of BFHX. Osthol was used as an internal standard (IS). Plasma samples were pretreated with methanol to precipitate protein. Chromatographic separation was accomplished using Hypersil GOLDTM C18 column (2.1 mm × 100 mm, 1.9 µm) with a gradient elution profile and a mobile phase consisting of (A) 0.1% formic acid in water and (B) acetonitrile and the flow rate was set at 0.2 mL/min. Multiple reaction monitoring (MRM) mode was applied to perform mass spectrometric analyses. All calibration curves were linear (r > 0.9908) in tested ranges. The intra- and inter-day accuracy and precisions of eight compounds at three different concentration levels were within the acceptable limits. The extraction recovery was within the range of 76.4 âˆ¼ 105.2% and the matrix effects were within the range of 88.3 âˆ¼ 115.0% (RSD ≤ 15.6%). The dilution effects were within the range of 90.2 âˆ¼ 114.9%. These 8 compounds were stable under the tested conditions. So the developed method was valid to evaluate the pharmacokinetic study of eight bioactive compounds after oral administration of BFHX.

Simultaneous characterization of multiple Psoraleae Fructus bioactive compounds in rat plasma by ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry for application in sex-related differences in pharmacokinetics.

A method for the simultaneous quantification of 13 bioactive compounds (psoralen, isopsoralen, isobavachin, bakuchalcone, neobabaisoflavone, bavachin, corylin, psoralidin, isobavachalcone, bavachinin, corylifol A, bavachalcone, and bakuchiol) by ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry has been developed and validated in rat plasma. Osthol was used as an internal standard and plasma samples were pretreated with one-step liquid-liquid extraction. These analytes were separated using a gradient mobile phase system of water and acetonitrile at a flow rate of 0.2 mL/min on a reverse-phase C18 column and analyzed in the selected multiple reactions monitoring mode. All calibration curves were linear (r > 0.9952) over the tested ranges. The intra- and interday accuracy and precisions of these analytes at three different concentration levels were within the acceptable limits of <15% at all concentrations. The mean recoveries of these analytes at three concentrations were more than 60.2% and the matrix effects were in the range of 85-115%. Stability studies proved that the analytes were stable under the tested conditions. The developed method was applied to evaluating the pharmacokinetic study of 13 bioactive compounds after oral administration of Psoraleae Fructus in rat of different genders. Some active compounds in Psoraleae Fructus had sex-related pharmacokinetics.

Imperatorin: A review of its pharmacology, toxicity and pharmacokinetics.

As a naturally occurring furanocoumarin, the medicinal value of imperatorin has been studied more and more. We hope to provide useful information for the further development of imperatorin by analyzing the literature of imperatorin in recent years. By collating the literature on the pharmacology of imperatorin, we found that the pharmacological activity of imperatorin is wide and imperatorin can be used for anti-cancer, neuroprotection, anti-inflammatory, anti-hypertension and antibacterial. In addition, we found that some researchers confirmed the toxicity of imperatorin. Pharmacokinetic studies demonstrated that oxidation metabolism is the main metabolic pathways of imperatorin. At present, the shortcomings of research on imperatorin mainly include: most pharmacological studies are concentrated in vitro, lacking enough in vivo experimental data; more and more studies showed that imperatorin has synergistic effect with other drugs in anticancer and other aspects, but lacking the detailed explanation of the mechanism of the synergistic effect; imperatorin has side effect, but it lacks enough experimental conclusions. Based on the above defects, we believe that more in vivo experiments of imperatorin should be carried out in the future; future research need to explore synergistic mechanisms of imperatorin with other drugs, especially in anticancer; the dose affects both the pharmacological activity and the side effect of imperatorin. The relationship between the dose and the two aspects need to be further studied in order to reduce the side effect. In addition, through structural modification of imperatorin, it is possible to improve the treatment effect and reduce side effect.

Effect of co-administration of Acori Tatarinowii Rhizoma volatile oil on pharmacokinetic fate of xanthotoxol, oxypeucedanin hydrate, and byakangelicin from Angelicae Dahuricae Radix in rat.

A combination of Angelicae Dahuricae Radix and Acori Tatarinowii Rhizoma has been widely used as the herb pair in traditional Chinese medicine to treat stroke, migraine, and epilepsy. However, the underlying synergistic mechanism of the herb pair remains unknown. This study was aimed at investigating the effects of Acori Tatarinowii Rhizoma volatile oil on the pharmacokinetic parameters of xanthotoxol, oxypeucedanin hydrate, and byakangelicin from Angelicae Dahuricae Radix in rat, and in vitro absorption behavior of the three compounds using rat everted gut sac, in situ single-pass intestinal perfusion, and Caco-2 cell monolayer models. The pharmacokinetic study exhibited clear changes in the key pharmacokinetic parameters of the three main coumarins through co-administering with Acori Tatarinowii Rhizoma volatile oil (50 mg/kg), the area under curve and the maximum plasma concentration of xanthotoxol increased 1.36 and 1.31 times; the area under curve, the maximum plasma concentration, mean residence time, half-life of elimination, and the time to reach peak concentration of oxypeucedanin hydrate increased by 1.35, 1.18, 1.24, 1.19 and 1.49 times, respectively; the area under curve, mean residence time, half-life of elimination, and time to reach peak concentration of byakangelicin climbed 1.29, 1.27, 1.37, and 1.28 times, respectively. The three coumarin components were absorbed well in the jejunum and ileum in the intestinal perfusion model, when co-administered with Acori Tatarinowii Rhizoma volatile oil (100 µg/mL). The in vivo and in vitro experiments showed good relevance and consistency. The results demonstrated that the three coumarin compounds from Angelicae Dahuricae Radix were absorbed through the active transportation, and Acori Tatarinowii Rhizoma volatile oil could promote the intestinal absorption and transport of these compounds by inhibiting P-glycoprotein (P-gp)-mediated efflux.

Simultaneous determination of multiple components in rat plasma and pharmacokinetic studies at a pharmacodynamic dose of Xian-Ling-Gu-Bao capsule by UPLC-MS/MS.

Xian-Ling-Gu-Bao capsule (XLGB) is an effective traditional Chinese medicine prescription (TCMP) that is used for the prevention and treatment of osteoporosis in China. A rapid, simple, efficient and stable method based on UPLC-MS/MS technology was developed for simultaneous determination of multiple components of XLGB in rat plasma. Mass spectrometric detection was performed in multiple reaction monitoring (MRM) mode with electrospray ionization (ESI). For twenty-one selected quantitative prototypes, all calibration curves showed favourable linearity (r>0.9932) in linear ranges. The lower limits of quantification (LLOQs) were 2 ng/mL for psoralen (PL), 2.5 ng/mL for asperosaponin VI (AS), 1 ng/mL for isopsoralen (IPS) and sweroside (SW), 0.5 ng/mL for magnoflorine (MA), bavachinin (BVN), tanshinone IIA (TA), timosaponin BII (TBII) and icaritin (ICT), 0.1 ng/mL for epimedin B (EB) and epimedin C (EC), 0.05 ng/mL for icariin (IC), isobavachalcone (IBC), psoralidin (PD), bavachin (BV), bavachalcone (BC), epimedin A (EA) and isobavachin (IBV), 0.02 ng/mL for neobavaisoflavone (NEO) and icariside I (ICI) and 0.01 ng/mL for icariside II (ICII). The intra-day and inter-day (low, medium, high) precision (relative standard deviation) for all analytes was less than 8.63%, and the accuracies (as relative error) were in the range of -12.45% to 8.91%. Extraction recoveries and matrix effects of analytes and IS were acceptable. All analytes were stable during the assay and storage in plasma samples. The validated method was successfully applied to the pharmacokinetics (PK) studies of the twenty-one prototypes at pharmacodynamic doses (0.3 and 1 g/kg/day). In addition, dynamic profiles of 28 metabolites (phase II conjugates: 23 glucuronide conjugates, 2 sulfate conjugates and 3 glucuronide or sulfate conjugates) were also monitored by their area/IS area-time curves. As a result, coumarins, prenylated flavonoids from Psoraleae Fructus, alkaloids and prenylated flavonol glycosides from Epimedii Herba, and iridoid glycosides, triterpenoid saponins from Dipsaci Asperoidis Radix were considered to be the key effective substances of XLGB due to their high exposure and appropriate pharmacokinetic features. This is the first report to reveal pharmacodynamic ingredients by a reversed pharmacodynamic (PD) - pharmacokinetics (PK) study.

Byakangelicin as a modulator for improved distribution and bioactivity of natural compounds and synthetic drugs in the brain.

BACKGROUND: The elucidation of the biological roles of individual active compounds in terms of their in vivo bio-distribution and bioactivity could provide crucial information to understand how natural compounds work together as treatments for diseases. PURPOSE: We examined the functional roles of Byakangelicin (Byn) to improve the brain accumulation of active compounds, e.g., umbelliferone (Umb), curcumin (Cur), and doxorubicin (Dox), and consequently to enhance their biological activities. METHODS: Active compounds were administered intravenously to mice, with or without Byn, after which organs were isolated and visualized for their ex vivo fluorescence imaging to determine the bio-distribution of each active compound in vivo. For the in vivo bioactivity, Cur, either with or without Byn, was administered to a lipopolysaccharide (LPS)-induced neuro-inflammation model for 5 days, and its anti-inflammatory effects were examined by ELISA using a brain homogenate and serum. RESULTS: We successfully demonstrated that the levels of active compounds (Umb, Cur, and Dox) in the brain, lung, and pancreas were greatly elevated by the addition of Byn via direct ex vivo fluorescence monitoring. In addition, sufficient accumulation of the active compound, Cur, greatly reduced LPS-induced neuro-inflammation in vivo. CONCLUSION: Byn could serve as a modulator to allow improved brain accumulation of diverse active compounds (Umb, Cur, and Dox) and enhanced therapeutic effects.

Blood-to-Retina Transport of Imperatorin Involves the Carrier-Mediated Transporter System at the Inner Blood-Retinal Barrier.

This study investigated the mechanism of transporting imperatorin across the inner blood-retinal barrier (iBRB). The carotid artery single injection method was used to calculate the retinal uptake index (RUI) of [3H]imperatorin in vivo, whereas the retinal capillary endothelial cell lines were used for the in vitro uptake and mRNA expression assays. RUI value of [3H]imperatorin was greater than that of the reference compound ([14C]n-butanol). [3H]Imperatorin significantly reduced the RUI in the presence of neuroprotective organic cationic drugs at 10 mM. However, tetraethylammonium and p-aminohippuric acid showed no significant effects. [3H]Imperatorin uptake by TR-iBRB2 cells was time-, pH-, energy-, and concentration-dependent with a Km value of 679 ± 130 µM. In addition, the uptake study showed insensitivity to sodium and membrane potential. Various organic cations including pyrilamine, nicotine, and clonidine significantly reduced the uptake of [3H]imperatorin, whereas organic anions and monocarboxylic acids did not. Furthermore, the mRNA expression level dropped markedly with rOCTN1, rOCTN2, rPMAT, and rMATE1 small interfering RNAs in the transfection study. Moreover, [3H]imperatorin uptake remained neutral with small interfering RNA transfections. Our results indicate that imperatorin transport across the iBRB involves carrier-mediated transporter system.

Evaluation of the Absorption Behavior of Main Component Compounds of Salt-Fried Herb Ingredients in Qing'e Pills by Using Caco-2 Cell Model.

Qing'e Pills is a Chinese traditional herbal product, which is often used to strengthen muscles and bones in TCM (traditional Chinese Medicine) practice. Its two main component herbs, namely, Cortex Eucommiae and Fructus Psoraleae are both required to be salt-fried according to TCM theory. We have evaluated the effects of salt-frying treated herbs on Caco-2 cell uptake behavior for those active ingredients of Qing'e Pills. By investigating of various variables, including MTT, temperature, inhibitors, pH, salt concentration and herb processing methods, we tried to clarify whether the salt-processing on herbs was necessary or not. Results showed that, compared to other processing methods, the salt-frying process significantly (p < 0.01) enhanced the absorption of effective components of Qing'e Pills. The way that psoralen, isopsoralen, psoralenoside and geniposide acid entered Caco-2 cells at low concentrations was via passive diffusion. These components were not substrates of P-glycoprotein. It demonstrated that the salt-frying process not only enhanced the concentration of active components in herb extract, but also changed their absorption behaviors. Nevertheless, the mechanism of absorption behavior changing needs to be further investigated.

Dietary furocoumarins and skin cancer: A review of current biological evidence.

Furocoumarins are a class of compounds produced by several plant species, including some popularly consumed by humans. Furocoumarins are known to be well absorbed from food sources, and can be rapidly distributed into several tissues including the skin. In human skin, when exposed to UV radiation, furocoumarins may become photoactivated and form interstrand crosslinks with DNA, thereby disrupting DNA transcription. Because of this property, furocoumarins have been combined as topical or oral agents with UV irradiation as a phototherapy to treat multiple skin conditions, yet these treatments have been shown to increase risk of both melanoma and non-melanoma skin cancer. Whether or not dietary furocoumarin exposure may confer the same risk is not yet known. This review summarizes the current evidence regarding the activities of ingested furocoumarins, with particular focus on how dietary furocoumarins are absorbed, metabolized, and distributed throughout the body, and their interactions with various cellular components that may underlie a potential relationship with skin cancer.

Simultaneous determination of saikosaponin a, paeonol, and imperatorin, components of DA-9805, in rat plasma by LC-MS/MS and application to a pharmacokinetic study.

DA-9805 is a new botanical antiparkinson drug candidate formulated using an ethanolic extract of the root of Bupleurum falcatum, the root cortex of Paeonia suffruticosa, and the root of Angelica dahurica. In this study, a sensitive and rapid LC-MS/MS method was developed to simultaneously determine, saikosaponin a, paeonol, and imperatorin, three active/representative ingredients of DA-9805, in rat plasma. Plasma was extracted by mixture of ethyl acetate and methyl tertiary butyl ether. Chromatographic separation was carried out using a C18 column and a gradient elution of mobile phases consisting of 5mM formic acid in water and acetonitrile. Total chromatographic run time was 10.5min. Multiple reaction monitoring mode was used for mass spectrometry; the transitions were m/z 779.5→617.2 for saikosaponin a in negative-ion mode, m/z 167→149 for paeonol and m/z 271.1→203 for imperatorin in positive-ion mode. Calibration curves were constructed in the range of 0.5-1000ng/mL for saikosaponin a, 20-10000ng/mL for paeonol, and 0.2-1000ng/mL for imperatorin. All the validation data, including the selectivity, linearity, precision, accuracy, recovery, matrix effect, and stability satisfied the acceptance requirements. The method was successfully applied in a pharmacokinetic study of saikosaponin a, paeonol, and imperatorin following oral administration of DA-9805.

[Determination and pharmacokinetics of main components for Psoralea corylifolia-Myristica fragrants drug pair by using UPLC-MS/MS].

To conduct multiple-reaction monitoring(MRM) quantitative analysis with ultra-high performance liquid chromatography coupled with mass spectrometry method(UPLC-MS/MS), determine the concentrations of psoralen, isopsoralen, bakuchiol and dehydrodiisoeugenol in plasma under positive iron mode with chloramghenicol as internal standard, and investigate the pharmacokinetics process of the main components before and after oral administration of drug pair Psoralea corylifolia -Myristica fragrants. Thirty-six SD rats were randomly divided into three group(A, B, C) and received P. corylifolia extract, P. corylifolia-M. fragrants extract, and M. fragrants extract respectively by intragastric administration. The plasma samples were collected at different time points. In the plasma samples, psoralen, isopsoralen, bakuchiol and dehydrodiisoeugenol showed good linear relationship within concentration rages of 0.098 125 to 39.25, 0.084 37 to 33.75, 0.046 875 to 18.75, and 0.11 to 2.2 mg•L⁻¹ respectively. The precision and stability results showed that the determination method of plasma concentration for such compositions was stable and reliable. The pharmacokinetic parameters obtained by DAS 2.0 showed varying differences before and after compatibility. According to the experimental results, the compatibility of P. corylifolia and M. fragrants can significantly impact the pharmacokinetic process of main components, expand their distribution and accelerate their metabolism and elimination in vivo.

[Preparation of isopsoralen loaded nanostructured carrier and its in vitro transdermal permeation characteristics].

To increase the permeation and retention of isopsoralen in skin, and improve its bioavailability.Isopsoralen loaded nanostructure liquid carrier (IPRN-NLC) was prepared by high pressure homogenization andoptimized by orthogonal experiment with the encapsulation efficiency, drug loading and average particle size as the evaluation indexes. The in vitro transdermal permeation of IPRN-NLC was evaluated by Franze diffusion cells.The results showed that solid-liquid lipid ratio of optimum IPRN-NLC formulation was 7∶3,drug-lipid ratio of 1∶30, 1% surfactant. Under these conditions, IPRN-NLC had an average encapsulation of （90.25±0.73）%,drug loading of （1.56±0.27）% and an average particle size of (305±1.57) nm.The in vitro transdermal permeation results showed that IPRN-NLC could increase the amount of IPRN permeated though skin, with 3 times of the epidermal retention as compared with IPRN solution. From the results we can know that the IPRN-NLC prepared by high pressure homogenization can improve the permeation andaccumulation of IPRN in the skin, with wide application prospects in the field of transdermal administration.

Simultaneous Determination of Three Furanocoumarins by UPLC/MS/MS: Application to Pharmacokinetic Study of Angelica dahurica Radix after Oral Administration to Normal and Experimental Colitis-Induced Rats.

In traditional oriental medicine, Angelica dahurica Radix (ADR) is used in the treatment of gastrointestinal, respiratory, neuromuscular, and dermal disorders. We evaluated the pharmacokinetic profiles of oxypeucedanin, imperatorin, and isoimperatorin, major active ingredients of ADR, in normal and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis rats. A rapid, sensitive, and validated UPLC/MS/MS method was established for evaluating the pharmacokinetics of three furanocoumarins. After oral administration of ADR (0.5 and 1.0 g/kg), blood samples were collected periodically from the tail vein. In colitis rats, the time to reach the peak concentration (Tmax) of imperatorin and isoimperatorin was significantly delayed (p < 0.05). Lower peak plasma concentrations (Cmax) and longer mean residence times for all furanocoumarins were also observed (p < 0.05) compared with normal rats. There was no significant difference in the area under the plasma concentration-time curve or elimination half-lives. Thus, the delayed Tmax and decreased Cmax, with no influence on the elimination half-life, could be colitis-related changes in the drug-absorption phase. Therefore, the prescription and use of ADR in colitis patients should receive more attention.

Simultaneous determination of imperatorin and its metabolite xanthotoxol in rat plasma and urine by LC-MS/MS and its application to pharmacokinetic studies.

An accurate, precise, selective, and sensitive liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of imperatorin (IMP) and its metabolite, xanthotoxol (XAN), in rat plasma and urine samples. The analytes, along with psoralen as an internal standard, were determined by multiple reaction monitoring (MRM) operated in the positive electrospray ionization (ESI) mode. Chromatographic separation was performed on an Acquity UPLC BEH C18 column (50mm×2.1mm, 1.7µm) with a mobile phase consisting of 0.1% formic acid solution and 0.1% formic acid in methanol at a flow rate of 0.3mL/min. The run time was 6min per sample and the injection volume was 5µL. The method had a lower limit of quantification (LLOQ) of 0.25ng/mL for IMP in plasma and urine, and 1ng/mL for XAN in urine. The linear calibration curves were fitted over the range of 0.25-1000ng/mL for IMP in plasma, 0.25-1000ng/mL for IMP in urine, and 1-1000ng/mL for XAN in urine, with correlation coefficients greater than 0.995. The inter- and intra-day accuracies (relative error, RE%) were between -8.5% and 3.5%, and the precisions (relative standard deviation, RSD%) were less than 10.0% for all quality control samples (QCs). The analytes were extracted from rat plasma and urine samples using a liquid-liquid extraction method with the extraction recovery in the range of 60.3-79.1%. A good stability of the analytes was observed in all the analysis procedures. The method was successfully validated and applied to determine the pharmacokinetics of IMP in rat plasma and, for the first time, the metabolite kinetics of IMP to XAN in rat urine after IMP administration.

UPLC-QTOF-MS/MS based screening and identification of the metabolites in rat bile after oral administration of imperatorin.

The detection of drug metabolites, particularly for minor metabolites, continues to be a challenge owing to the complexity of biological samples. Imperatorin is an active natural furocoumarin ingredient originating from many traditional Chinese herbal medicines. In the present study, the metabolites of imperatorin after oral administration were qualitatively investigated, and possible metabolic pathways of it were subsequently proposed. Bile samples were collected after oral administration and pretreated by the application of Waters Ostro. The QTOF-MS/MS data was acquired using ultra high performance liquid chromatography coupled to quadrupole time flight spectrometry (UPLC-QTOF-MS). Based on this analytical strategy, 32 metabolites (23 phase I and 9 phase II metabolites) were identified in rat bile. The results demonstrated that C5H8 could be easily eliminated from imperatorin forming the metabolite M1. It also indicated that imperatorin and M1 underwent extensive metabolic reactions including oxidation, hydrolysis, methylation, glucuronide conjugation, C2H5NO2S conjugation and C3H5NO2S conjugation. This is the first study of imperatorin metabolism in bile samples. The proposed metabolic pathways in this research will provide essential data for further pharmaceutical studies of other linear-type furocoumarins.

Evaluation of the influence of salt processing on pharmacokinetics of psoralen and isopsoralen in Psoralea corylifolia L.

A sensitive, specific and rapid ultra-high-pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method has been developed to investigate pharmacokinetic properties of psoralen and isopsoralen, two compounds isolated from raw/salt-processed fruit of Psoralea corylifolia L. UHPLC-MS/MS was used with positive ion electrospray. The mobile phase was composed of acetonitrile and 0.1% formic acid aqueous solution and a gradient elution program at flow rate of 0.3 mL/min was applied. Multiple reaction monitoring mode was used for the quantification of psoralen, isopsoralen ([M + H](+) m/z 187.0 → m/z 131.0) and scoparone (m/z 207.0 → m/z 151.1). Scoparone served as an internal standard. The method was fully validated for its sensitivity, selectivity, stability, matrix effect and extraction recovery. The obtained results showed that salt-processed Buguzhi significantly promoted the absorption of psoralen and isopsoralen, and increased the bioavailability of these compounds.

Assessment of 8-methosypsoralen, lomefloxacin, sparfloxacin, and Pirfenidone phototoxicity in Long-Evans rats.

Phototoxicity has a strong impact on drug development. Although several animal models have been developed to quantitatively assess human risks, none have been validated for standardized use. In this study, we validated an in vivo phototoxicity model using Long-Evans (LE) rats treated with 4 well-known phototoxic drugs, namely 8-methoxypsoralen, lomefloxacin, sparfloxacin, and pirfenidone. Daily macroscopic observations of skin and eyes, ophthalmological examinations 4 days after dosing, and blood sampling for toxicokinetics (TKs) were performed after exposure of treated animals to ultraviolet, and dose-dependent eye and/or skin reactions were noted for all compounds. Margins of safety were calculated when possible and correlated well with known relative phototoxicity of the 4 compounds. We conclude that the present in vivo phototoxicity assay using LE rats with TK analysis can be used to quantitatively predict the risk of pharmaceutical phototoxicity in humans.

Simultaneous determination of osthole, bergapten and isopimpinellin in rat plasma and tissues by liquid chromatography-tandem mass spectrometry.

A highly selective and sensitive method for simultaneous quantitation of osthole, bergapten and isopimpinellin in rat plasma and tissues was developed by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). After liquid-liquid extraction of samples with methyl tert-butyl ether, the analytes and dextrorphan (internal standard, IS) were separated by a Hypersil GOLD AQ C18 column with gradient elution of acetonitrile and water containing 0.5‰ formic acid. Three determinands were detected using an electrospray ionization (ESI) tandem mass spectrometry in the multiple reaction monitoring (MRM) modes with positive electrospray ionization. Calibration curves were recovered over the concentration ranges of 1-200 ng/ml, 1-500 ng/ml, 0.25-200 ng/ml for osthole, bergapten and isopimpinellin in plasma; 1-100 ng/ml, 1-500 ng/ml, 0.5-100 ng/ml for osthole, bergapten and isopimpinellin in tissues, respectively. The intra-day precision (R.S.D.) was within 13.90% and the intra-day accuracy (R.E.) was within -6.27 to 6.84% in all biological matrixes. The inter-day precision (R.S.D.) was less than 13.66% and the inter-day accuracy (R.E.) was within -10.64 to 13.04%. Then the method was successfully applied to investigate plasma pharmacokinetic study and tissue distribution of osthole, bergapten and isopimpinellin in rats after oral administration of Fructus Cnidii extraction, especially for testis/uterus tissue distribution. The results demonstrated that osthole, bergapten and isopimpinellin were absorbed and eliminated rapidly with wide distributions in rats. Distribution data of these three bioactive components in testis/uterus tissues could offer useful information for the further preclinical and clinical studies of Fructus Cnidii in the treatment of genital system disease.