Soo-Min Cho

Pharmacokinetic properties and antitumor efficacy of the 5-fluorouracil loaded PEG-hydrogel

BackgroundWe have studied the in vitro and in vivo utility of polyethylene glycol (PEG)-hydrogels for the development of an anticancer drug 5-fluorouracil (5-FU) delivery system.MethodsA 5-FU-loaded PEG-hydrogel was implanted subcutaneously to evaluate the drug retention time and the anticancer effect. For the pharmacokinetic study, two groups of male rats were administered either an aqueous solution of 5-FU (control group)/or a 5-FU-loaded PEG-hydrogel (treated group) at a dose of 100 mg/kg. For the pharmacodynamic study, a human non-small-cell lung adenocarcinoma (NSCLC) cell line, A549 was inoculated to male nude mice with a cell density of 3 × 106. Once tumors start growing, the mice were injected with 5-FU/or 5-FU-loaded PEG-hydrogel once a week for 4 weeks. The growth of the tumors was monitored by measuring the tumor volume and calculating the tumor inhibition rate (IR) over the duration of the study.ResultsIn the pharmacokinetic study, the 5-FU-loaded PEG-hydrogel gave a mean residence time (MRT) of 8.0 h and the elimination half-life of 0.9 h; these values were 14- and 6-fold, respectively, longer than those for the free solution of 5-FU (p < 0.05). In the pharmacodynamic study, A549 tumor growth was significantly inhibited in the 5-FU-loaded PEG-hydrogel group in comparison to the untreated group beginning on Day 14 (p < 0.05-0.01). Moreover, the 5-FU-loaded PEG-hydrogel group had a significantly enhanced tumor IR (p < 0.05) compared to the free 5-FU drug treatment group.ConclusionWe suggest that 5-FU-loaded PEG-hydrogels could provide a useful tool for the development of an anticancer drug delivery system.

Effect of 5-FU and MTX on the Expression of Drug-resistance Related Cancer Stem Cell Markers in Non-small Cell Lung Cancer Cells

Cancer stem cells (CSCs) are often characterized by the elevated expression of drug-resistance related stem-cell surface markers, such as CD133 and ABCG2. Recently, we reported that CSCs have a high level of expression of the IL-6 receptor (IL-6R). The purpose of this study was to investigate the effect of anticancer drugs on the expression of the drug resistance-related cancer stem cell markers, ABCG2, IL-6R, and CD133 in non-small cell lung cancer (NSCLC) cell lines. A549, H460, and H23 NSCLC cell lines were treated with the anticancer drugs 5-fluorouracil (5-FU; 25 µg/ml) and methotrexate (MTX; 50 µg/ml), and the expression of putative CSC markers was analyzed by fluorescent activated cell sorter (FACS) and the gene expression level of abcg2, il-6r and cd133 by reverse transcriptasepolymerase chain reaction (RT-PCR). We found that the fraction of ABCG2-positive(+) cells was significantly increased by treatment with both 5-FU and MTX in NSCLC cells, and the elevation of abcg2, il-6r and cd133 expressions in response to these drugs was also confirmed using RT-PCR. Also, the number of IL-6R(+) cells was increased by MTX in the 3 cell lines mentioned and increased by 5-FU in the H460 cell line. The number of CD133(+) cells was also significantly increased by both 5-FU and MTX treatment in all of the cell lines tested. These results indicate that 5-FU and MTX considerably enhance the expression of drug-resistance related CSC markers in NSCLC cell lines. Thus, we suggest that antimetabolite cancer drugs, such as 5-FU and MTX, can lead to the propagation of CSCs through altering the expression of CSC markers.

Simultaneous detection of flumethasone, dl-methylephedrine, and 2-hydroxy-4,6-dimethylpyrimidine in porcine muscle and pasteurized cow milk using liquid chromatography coupled with triple-quadrupole mass spectrometry.

A simple analytical method based on liquid chromatography coupled with triple-quadrupole mass spectrometry was developed for detection of the veterinary drugs flumethasone, dl-methylephedrine, and 2-hydroxy-4,6-dimethylpyrimidine in porcine muscle and pasteurized cow milk. The target drugs were extracted from samples using 10mM ammonium formate in acetonitrile followed by clean-up with n-hexane and primary secondary amine sorbent (PSA). The analytes were separated on an XBridge™ hydrophilic interaction liquid chromatography (HILIC) column using 10mM ammonium formate in ultrapure water and acetonitrile. Good linearity was achieved over the tested concentrations in matrix-fortified calibrations with correlation coefficients (R(2))≥0.9686. Recovery at two spiking levels ranged between 73.62-112.70% with intra- and inter-day precisions of ≤20.33%. The limits of quantification ranged from 2-10ng/g in porcine muscle and pasteurized cow milk. A survey of market samples showed that none of them contained any of the target analytes. Liquid-liquid purification using n-hexane in combination with PSA efficiently removed the interferences during porcine and milk sample extraction. The developed method is sensitive and reliable for detection of the three target drugs in a single chromatographic run. Furthermore, it exhibits high selectivity and low quantification limits for animal-derived food products destined for human consumption.

Determination of the esculetin contents of medicinal plants by liquid chromatography-tandem mass spectrometry.

We developed a LC-MS/MS method for the determination of esculetin contents in medicinal plants. The analysis was performed using multiple reaction monitoring in negative mode, and an XBridge™ C(18) column (2.1 × 100 mm, 3.5 µm) was used. Methanol and 0.1% formic acid were used for gradient analysis. The calibration curve showed good linearity (r(2)  > 0.9993). The limits of detection and quantitation were 0.02 and 0.07 ng/mL, respectively. The intra-day and inter-day precisions were 1.5-6.8 and 2.0-5.3%, respectively, and the accuracy was 102.0-110.2%. The contents of esculetin in 35 different plants were determined, and Fraxini Cortex showed the highest content of esculetin (761-5475 mg/kg). In Mori Folium and Artemisiae Capillaris Herba, 5.2-21.5 and 7.0-17.6 mg/kg of esculetin were found, respectively. In other medicinal plants, no esculetin was detected, or it was present at a concentration less than 10 mg/kg. The analysis method appears to be simple, sensitive and reproducible. Contrary to expectations based on traditional medical knowledge, although Artemisiae Capillaris Herba contains a large amount of esculetin, it appears from this study that Fraxini Cortex contains a greater amount. The pharmacological effects of esculetin isolated from medicinal plants should be investigated as part of new medicines development.

Bithionol residue analysis in animal-derived food products by an effective and rugged extraction method coupled with liquid chromatography–tandem mass spectrometry

Herein, we developed a simple analytical procedure for the quantitation of bithionol residues in animal-derived food products such as porcine muscle, eggs, milk, eel, flatfish, and shrimp using a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method coupled with liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI+/MS-MS). Samples were extracted with 0.1% solution of formic acid in acetonitrile and the extract was purified using a C18 sorbent. Separation was performed on a Waters XBridge™ C18 reversed-phase analytical column using 0.1% solution of formic acid/acetonitrile as the mobile phase. Six-point matrix-matched calibration indicated good linearity, with the calculated coefficients of determination (R2) being≥0.9813. Intra- and inter-day recoveries (determined at spiking levels equivalent to 1×and 2×the limit of quantitation (0.25μg/kg)) ranged between 80.0 and 94.0%, with the corresponding relative standard deviations (RSDs) being≤8.2%. The developed experimental protocol was applied to different samples purchased from local markets in Seoul, which were tested negative for bithionol residues. In conclusion, the proposed method proved to be versatile and precise, being ideally suited for the routine detection of bithionol residues in animal-derived food products with various protein and fat contents.

Simultaneous determination of water-soluble whitening ingredients and adenosine in different cosmetic formulations by high-performance liquid chromatography coupled with photodiode array detection

The Korean Cosmetic Act regulates the use of functional cosmetics) by the law. Four functional cosmetic groups, whitening, anti‐wrinkle, UV protection and combination of whitening and anti‐wrinkle, were categorized according to the Korean Cosmetic Act and Functional Cosmetics Codex. In this study, high‐performance liquid chromatography (HPLC) coupled with photodiode array detection (DAD) was employed for the simultaneous detection of arbutin (and its decomposition product, hydroquinone), niacinamide, ascorbyl glucoside, ethyl ascorbyl ether and adenosine in functional cosmetic products such as creams, emulsions and lotions.

Determination of residual levels of naloxone, yohimbine, thiophanate, and altrenogest in porcine muscle using QuEChERS with liquid chromatography and triple quadrupole mass spectrometry

A quick, easy, cheap, effective, rugged, and safe QuEChERS (method) was used for the simultaneous detection of four veterinary drug residues, namely naloxone, yohimbine, thiophanate, and altrenogest, in porcine muscle, using liquid chromatography with electrospray ionization triple quadrupole tandem mass spectrometry. Because of the unavailability of a suitable internal standard, matrix-matched calibrations were used for quantification, with determination coefficients ≥ 0.9542. The accuracy (expressed as recovery %) ranged from 60.53 to 83.25%, and the intra- and interday precisions (expressed as relative standard deviations) were <12%. The limits of quantification were 5, 0.5, 2, and 5 ng/g for naloxone, yohimbine, thiophanate, and altrenogest, respectively. Samples purchased from local markets in Seoul, Republic of Korea, revealed no traces of the target analytes. The developed method described herein is sensitive and reliable and can be applied to quantify the tested veterinary drugs in animal tissues.

Development and validation of modified QuEChERS method coupled with LC-MS/MS for simultaneous determination of cymiazole, fipronil, coumaphos, fluvalinate, amitraz, and its metabolite in various types of honey and royal jelly.

Over the past few decades, honey products have been polluted by different contaminants, such as pesticides, which are widely applied in agriculture. In this work, a modified EN - quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method was developed for the simultaneous quantification of pesticide residues, including cymiazole, fipronil, coumaphos, fluvalinate, amitraz, and its metabolite 2,4-dimethylaniline (2,4-DMA), in four types of honey (acacia, wild, chestnut, and manuka) and royal jelly. Samples were buffered with 0.2M dibasic sodium phosphate (pH 9), and subsequently, acetonitrile was employed as the extraction solvent. A combination of primary secondary amine (PSA) and C18 sorbents was used for purification prior to liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI+/MS-MS) analysis. The estimated linearity measured at six concentration levels presented good correlation coefficients (R2)≥0.99. The recovery, calculated from three different spiking levels, was 62.06-108.79% in honey and 67.58-106.34% in royal jelly, with an RSD<12% for all the tested compounds. The matrix effect was also evaluated, and most of the analytes presented signal enhancement. The limits of quantification (LOQ) ranged between 0.001 and 0.005mg/kg in various samples. These are considerably lower than the maximum residue limits (MRL) set by various regulatory authorities. A total of 43 market (domestic and imported) samples were assayed for method application. Among the tested samples, three samples were tested positive (i.e. detected and quantified) only for cymiazole residues. The residues in the rest of the samples were detected but not quantified. We concluded that the protocol developed in this work is simple and versatile for the routine quantification of cymiazole, 2,4-DMA, fipronil, coumaphos, amitraz, and fluvalinate in various types of honey and royal jelly.

Quantification of bupivacaine hydrochloride and isoflupredone acetate residues in porcine muscle, beef, milk, egg, shrimp, flatfish, and eel using a simplified extraction method coupled with liquid chromatography–triple quadrupole tandem mass spectrometry

In this study, a simple analytical approach has been developed and validated for the determination of bupivacaine hydrochloride and isoflupredone acetate residues in porcine muscle, beef, milk, egg, shrimp, flatfish, and eel using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A 0.1% solution of acetic acid in acetonitrile combined with n-hexane was used for deproteinization and defatting of all tested matrices and the target drugs were well separated on a Waters Xbridge™ C18 analytical column using a mobile phase consisting of 0.1% acetic acid (A) and 0.1% solution of acetic acid in methanol (B). The linearity estimated from six-point matrix-matched calibrations was good, with coefficients of determination ≥0.9873. The limits of quantification (LOQs) for bupivacaine hydrochloride and isoflupredone acetate were 1 and 2ngg-1, respectively. Recovery percentages in the ranges of 72.51-112.39% (bupivacaine hydrochloride) and 72.58-114.56% (isoflupredone acetate) were obtained from three different fortification concentrations with relative standard deviations (RSDs) of <15.14%. All samples for the experimental work and method application were collected from the local markets in Seoul, Republic of Korea, and none of them tested positive for the target drugs. In conclusion, a simple method using a 0.1% solution of acetic acid in acetonitrile and n-hexane followed by LC-MS/MS could effectively extract bupivacaine hydrochloride and isoflupredone acetate from porcine muscle, beef, milk, egg, shrimp, flatfish, and eel samples.

Nonlinear toxicokinetics of enrofloxacin in rats

The dose-dependent toxicokinetics of enrofloxacin were studied by administering various single subcutaneous doses (5, 10, 20, 40, 70, 100, 150, 200, 300 and 400 mg/kg) in male Sprague-Dawley rats. The blood samples were collected from the tail veins, and the plasma concentration of enrofloxacin was determined by an HPLC-fluorescence detection (FLD) method. The time-concentration profiles of enrofloxacin were well fitted by an one-compartmental model with first order elimination. The absorption half-lives (t1/2abs) ranged from 0.2–0.8 h, and the mean time to maximum plasma concentration (Tmax) ranged from 0.6–1.8 h. On the other hand, marked disproportionate increases of the area under the curve (AUC) and elimination half-lives (t1/2) were observed from the increase of the doses. This result indicates that the elimination of enrofloxacin has nonlinear pharmacokinetic properties with increasing doses. Therefore, we need to take into consideration the possible occurrence of side effects resulting from greater systemic exposure from high dose therapies.