Identification of novel sildenafil-analogues in an adulterated herbal food supplement

Towards a decade of detecting new analogues of sildenafil, tadalafil and vardenafil in food supplements: A history, analytical aspects and health risks

“…Examples are dithio-desmethylcarbodenafil [53], two dihydro-derivatives of acetildenafil [54] and nitroso-prodenafil [55]. Out of these four analogues, only 22-dihydro-acetildenafil had already been disclosed in patent literature [30].…”

“…Nitroso-prodenafil was recognized as unstable and the effect of methanolic/aquatic work-up was investigated by rinsing the capsule content with CDCl 3 prior to NMR analysis [55]. A possible degradation product that was not accounted for is the case of two hydroxyl-derivatives of acetildenafil detected in one capsule [54]. One of the analogues (22-dihydro-acetildenafil) is an analogue already known from patent literature [30].…”

“…Piperidino-vardenafil, Pseudo-vardenafil Piperidenafil [18,20,111] toxicology and pharmacology of the analogues are largely uncharted. Nevertheless, the presence of impurities and degradation products underlines the carelessness of the manufacturers [54,75].…”

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“…Seven of these have already been previously published (piperazionafil, isopiperzionafil, oxoacetildenafil, (Z)-/ (E)-dicholorodenafil, gendenafil, and hydrohomoacetildenafil) [78]. The parent structure of sildenafil as well as its five analogues was also detected using LC-MS, UV, and NMR spectroscopic methods [79]. Liang et al [2] proposed a method of LC/MS/MS because it is both rapid and reliable for the screening of complex matrices in a single run.…”

“…Liang et al [2] used MRM to screen a mixture of compounds simultaneously by using three selected transitions for each compound to improve reliability on relative peak areas. Transitions are monitored under Optimal Collision Energy (OCE) and the analysis was sped up without compromising the mobile phases and also by having high selective MS/MS to ensure specificity [79]. When the LC/MS/MS method was tested, 74 of 200 samples tested positive for adulterants without false positives or false negatives.…”