Bosco Chen Bloodworth

Isolation and identification of thiohomosildenafil and thiosildenafil in health supplements

Two unknown compounds are detected and isolated from health supplements for the enhancement of sexual function. The structures of the unknown compounds are elucidated using high-resolution MS, ESI-MS/MS, NMR, UV and IR. One compound is identified as an analogue of sildenafil in which the oxygen atom is substituted with a sulfur atom in the pyrazolopyrimidine moiety, and an ethyl group instead of a methyl group is attached to the piperazinyl nitrogen. Hence, this compound is named thiohomosildenafil. Another compound is also a sildenafil analogue in which the oxygen atom is substituted with a sulfur atom in the pyrazolopyrimidine moiety. This compound is named thiosildenafil. Both the two compounds are first detected in health supplements. The UV, IR and completely assigned NMR data of thiohomosildenafil and thiosildenafil are first reported.

Identification of benzamidenafil, a new class of phosphodiesterase-5 inhibitor, as an adulterant in a dietary supplement

A sample labeled to be a natural herbal supplement for the enhancement of sexual function, was sent to Health Sciences Authority (HSA) of Singapore for testing. An unknown compound was detected and isolated from the product. The structure of the unknown compound was identified using LC-UV, high-resolution MS, ESI-MS/MS, IR, and NMR. The compound was characterized as a phosphodiesterase-5 (PDE-5) inhibitor, benzamidenafil. This is the first report of benzamidenafil, representing a new class of PDE-5 inhibitors, as an adulterant of a dietary supplement.

Structural elucidation of a PDE-5 inhibitor detected as an adulterant in a health supplement

A PDE-5 inhibitor was detected and isolated from a health supplement claimed to be a preparation of fresh oyster extracts and be able to promote and support healthy sexual function and endurance, etc. The structure of this PDE-5 inhibitor was elucidated using LC-UV, LC-TOF-MS, MS-MS, IR spectroscopy, and 2D NMR. It was characterized as 8-(2-(4-(hydroxymethyl)piperidin-1-yl)benzylamino)-3-ethyl-1H-imidazo[4,5-g]quinazoline-2(3H)-thione, a compound reported to be a PDE-5 inhibitor.

Isolation and identification of hydroxythiohomosildenafil in herbal dietary supplements sold as sexual performance enhancement products

An unknown compound is detected and isolated from two herbal dietary supplements bought on the internet. The structure of the unknown compound is elucidated using ESI–MS/MS, NMR, UV and IR. The compound, named hydroxythiohomosildenafil, is identified as an analogue of sildenafil in which the oxygen atom is substituted with a sulfur atom in the pyrazolopyrimidine moiety, and a hydroxyethyl group instead of a methyl group is attached to the piperazinyl nitrogen. It is the first report of this compound being detected in herbal dietary supplements. The UV, IR and completely assigned NMR data of hydroxythiohomosildenafil is recorded.

Isolation and structural elucidation of dapoxetine as an adulterant in a health supplement used for sexual performance enhancement.

A health supplement used for sexual performance enhancement was sent to Health Sciences Authority of Singapore for testing. An unknown compound was detected and isolated and its structure was elucidated using NMR, high-resolution MS, ESI-MS/MS, UV and IR. The compound, dapoxetine, is reported to be a selective serotonin reuptake inhibitor under investigation for the treatment of premature ejaculation.

Metabolite profiling of edible bird's nest using gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry.

RATIONALE Edible birds nest (EBN) is a renowned food item in the Chinese community due to the therapeutic effects claimed to be brought about by its consumption. However, very little scientific information has been revealed to support these claims. Thus, metabolite profiling was performed to identify the metabolites and to relate them to the medicinal properties of EBN. The study also aims to further extend the results to determine any possible differences when the EBNs are classified according to their coloration, countries or production sites. METHODS Extraction of the metabolites was performed via sonication of EBN with methanol and chloroform. Two analytical platforms, namely gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS), were utilized to detect the metabolites. This multi-analytical platform would provide a comprehensive coverage of the metabolites in EBN. GC/MS analysis was conducted in scan mode from m/z 50-650. On the other hand, LC/MS analysis was operated in both positive and negative ion mode from m/z 150-1000. RESULTS Metabolites were identified and their relationships with the medicinal properties of EBN were deduced. Classification with chemometrics illustrates that EBNs could be differentiated according to their coloration, countries and production sites. This differentiation was due to the environment where the EBNs are produced. Furthermore, GC/MS was demonstrated to be more suitable for classification as the processing methods of the EBNs did not cause a significant variation in the metabolites detected by GC/MS. CONCLUSIONS The overall findings suggest that the novel approach of metabolite profiling offers new insights to understanding EBN and provided evidence to support the medicinal properties of EBN. In addition, the success of classification of EBNs with metabolite profiling combining with chemometrics represents a paradigm shift in the quality control of this food item.

Structural elucidation of propoxyphenyl isobutyl aildenafil, adulterant in a health supplement using high-resolution Orbitrap mass spectrometry

A new sildenafil analogue, propoxyphenyl isobutyl aildenafil has been found in trace quantity from one health supplement. It has been purified by preparative high performance liquid chromatography (HPLC). The structural elucidation of this compound has been carried out using high-resolution Orbitrap mass spectrometry under two fragmentation modes, namely High energy Collision Dissolution (HCD) and Collision Induced Dissolution (CID). Under MS(3) experiments and CID mode, the isobutyl-bonded fragments of propoxyphenyl isobutyl aildenafil at m/z 313 and 297 have been compared with the reference ions derived from isobutyl sildenafil. The accurate mass measurement of each product ions has been carried out with the aid of Mass Frontier software (version 5.0). The mass error of all product ions is not more than 5.0ppm.

Isolation and structural elucidation of a new sildenafil analogue from a functional coffee.

A sildenafil analogue was detected in a functional coffee sample labelled to have male sexual performance enhancement effects. This analogue was isolated and purified by flash chromatography and preparative high-performance liquid chromatography. Its structure was elucidated using high-resolution mass spectrometry; electrospray ionization-tandem mass spectrometry; and nuclear magnetic resonance spectroscopy, ultraviolet spectroscopy, and infrared spectroscopy. Compared with sildenafil, instead of an N-methylpiperazinyl moiety, ring opening of the piperazine ring with the loss of a carbon atom resulted in a substituted benzenesulfonamide. The chemical name of this analogue is N-[2-(dimethylamino)ethyl]-4-ethoxy-3-(1-methyl-7-oxo-3-propyl-6,7-dihydro-1H-pyrazolo[4,3-d]pyrimidin-5-yl)benzenesulfonamide. It is named descarbonsildenafil because it has one less carbon atom when compared with sildenafil.

Analysis of 32 toxic natural substances in herbal products by liquid chromatography quadrupole linear ion trap mass spectrometry.

In this study, an LC-MS/MS EPI method was developed for simultaneous determination of 32 toxic natural substances in herbal products. The analytes include aconite alkaloids, lobelia alkaloids, solanaceous alkaloids, digitalis steroid glycosides, strychnine, tetrahydropalmatine etc. They werecommonly used in herbal products. The target analytes were extracted from the samples using theQuEChERS method and analysed using AB SCIEX QTRAP 5500 coupled with Agilent HPLC 1260. Thecolumn used was biphenyl reversed phase analytical column. Mobile phase A and B were deionizedwater and methanol respectively, both containing 5mM ammonium formate and 0.1% formic acid. TheMRM-IDA-EPI method enabled quantification and confirmation of the analytes in a single run. The EPIwas used for the qualitative analysis while the MRM was used for the quantitative analysis. Limits ofdetection were determined to be below 10μg/kg for the majority of the analytes. The recoveries forthose commonly detected natural substances were in the acceptable range of 70-120%.