Screening sexual performance enhancing compounds and their analogues in counterfeit and illicit erectile dysfunction drugs by high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry.

The growth of the counterfeit and illicit drugs market is attributable in part to phosphodiesterase type-5 inhibitor (PDE-5is) medications for erectile dysfunction (ED). PDE-5is and their analogues are being increasingly supplied as counterfeit and illicit drugs marketed to enhance sexual performance. Herein, we screened and confirmed a total of 181 such counterfeit and illicit drugs used to date to enhance sexual performance by high-performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Modeling the early temporal dynamics of viral load in respiratory tract specimens of COVID-19 patients in Incheon, the Republic of Korea.

Objective: To investigate the duration and peak of severe acute respiratory syndrome coronavirus 2 shedding as infectivity markers for determining the isolation period.

Methods: A total of 2,558 upper respiratory tract (URT) and lower respiratory tract (LRT) specimens from 138 patients with laboratory-confirmed coronavirus disease were analyzed. Measurements of sequential viral loads were aggregated using the cubic spline smoothing function of a generalized additive model.

Enhancement of 5-HT receptor function and blockade of Kv1.5 by MK801 and ketamine: implications for PCP derivative-induced disease models.

MK801 and ketamine, which are phencyclidine (PCP) derivative N-methyl-d-aspartate receptor (NMDAr) blockers, reportedly enhance the function of 5-hydroxytryptamine (HT)-2A receptors (5-HTRs). Both are believed to directly affect the pathogenesis of schizophrenia, as well as hypertension. 5-HTR signaling involves the inhibition of Kv conductance.

Development and validation of UPLC and LC-MS/MS methods for the simultaneous determination of anti-obesity drugs in foods and dietary supplements.

Recently, the number of the cases in which weight loss products have been sold with illegal adulterants has increased, as awareness of the problems of obesity grows. In this study, we developed simultaneous analysis methods to rapidly and accurately identify ingredients illegally mixed with foods and dietary supplements. Twenty-three anti-obesity drugs in foods and dietary supplements were determined by developed and validated UPLC and LC-MS/MS methods.

Screening for Corticosteroid Adulterants in Korean Herbal Medicines.

The objective of this study was to determine the presence of corticosteroids in illegal herbal medicines using ultra-high-performance liquid chromatography-tandem mass spectrometry. We collected 212 herbal medicine samples that were advertised as being effective for treatment of joint pain and bone aches. Samples were from the Korean commercial market during a span of four years (2010-2013), and the method was validated.

Development and validation of an LC-MS/MS method for the simultaneous analysis of 28 specific narcotic adulterants used in dietary supplements.

The purpose of this study was to develop a method to analyse the concentration of multiple illegal narcotics present in dietary supplements. To this end, we established and optimised a procedure using LC-MS/MS simultaneously to analyse 28 narcotic compounds in various forms of dietary supplements, including powders, tablets, liquids and capsules. In addition, candy and cookies that have also had detected cases of adulteration were also analysed.

Identification and screening of a tadalafil analogue found in adulterated herbal products.

A tadalafil analogue was detected in an herbal product by high performance liquid chromatography-diode array detector (HPLC-DAD) with a similar chromatographic retention time to tadalafil. The compounds were separated using semi-preparative HPLC. The structure of the detected tadalafil analogue was elucidated by LC-quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) and nuclear magnetic resonance (NMR) spectroscopy.

LC-ESI-MS/MS analysis of phosphodiesterase-5 inhibitors and their analogues in foods and dietary supplements in Korea.

A number of 188 food and dietary supplement samples were collected from 2009 to the first half of 2013 in Korean online and offline stores. A method to identify phosphodiesterase-5 (PDE-5) inhibitors and their analogues using liquid chromatography-electrospray ionisation-mass spectrometry/mass spectrometry (LC-ESI-MS/MS) was validated. Limit of detection and limit of quantitation of liquid-type and solid-type negative samples ranged from 0.

Development and validation of an ultra-performance liquid chromatography method for simultaneous analysis of 20 antihistaminics in dietary supplements.

The purpose of this study was to develop and validate an ultra-performance liquid chromatography method for simultaneous analysis of 20 antihistamines (illegal additives) in dietary supplements. The limits of detection and quantitation of the method ranged from 1.5 to 2.

Monitoring of 35 illegally added steroid compounds in foods and dietary supplements.

The adulteration of foods and dietary supplements with steroids has been well attested and has the potential to be dangerous owing to various possible side-effects. Therefore, detecting the presence of steroids in various health food products has become increasingly important. The purpose of this study was to monitor illegally adulterated health food products by applying multiple reaction monitoring techniques to tandem liquid chromatography-mass spectrometry (LC-MS/MS).

In vitro study of Organization for Economic Co-operation and Development (OECD) endocrine disruptor screening and testing methods- establishment of a recombinant rat androgen receptor (rrAR) binding assay.

The androgen receptor (AR) binding assay can be used to determine the ability of probable endocrine disruptors (EDs) to compete with synthetic androgen methyltrienolone (R1881) for binding to recombinant rat AR (rrAR). In this study, we assessed AR binding of various chemicals using Lexius Freyberger's method. The rank of relative binding affinity (RBA, IC(50)) on the tested chemicals was trenbolone 1.

Gene expression profile by 2,3,7,8-tetrachlorodibenzo-p-dioxin in the liver of wild-type (AhR+/+) and aryl hydrocarbon receptor-deficient (AhR-/-) mice.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is one of the most toxic environmental pollutants that cause various biological effects on mammals. The purpose of our study was to identify the genes involved in hepatotoxicity and hepatocarcinogenesis caused by TCDD. C57BL/6 (AhR+/+, wild type) and B6.

Flow cytometric assessment of ethylene glycol monoethyl ether on spermatogenesis in rats.

The effects of ethylene glycol monoethyl ether (EGEE) on testicular cell populations in rats were investigated by a flow cytometric method. Rats were administered by gavage with EGEE at the various doses of 0 (saline alone), 100, 200, 400, and 800 mg/kg body weight/day for 4 weeks. The treatment of EGEE caused decreases in the weight of testis and epididymis and in the number of testicular cells.