A substantially available identiˆcation system for Sildenaˆl in health foods was established using 3 diŠerent analytical methods; i.e. TLC, preparative TLC/MS and HPLC/photo-diode array. Sildenaˆl in health foods was extracted with ethyl acetate under alkaline conditions as sample solutions for TLC and preparative TLC, and also extracted with 50％ methanol and then diluted with solution of HPLC mobile phase for HPLC. The sample solution for TLC was applied to Silica gel 60 F 254 plates with chloroform/methanol/28％ ammonia (90：1：5, under layer) as mobile phase. Spots were located under UV radiation at 254 nm and 366 nm, and spraying dragendorŠ reagent. The conditions for preparative TLC were the same as these of TLC method, and samples abtained from preparative TLC were determined by MS with APCI interface, under both positive and negative modes. The HPLC analysis was carried out on a column of Cosmosil 5C18-AR(4.6 mm×150 mm, 5 mm) with 0.05 mol/l phosphate buŠer pH 3.0/acetonitrile(73：27) as mobile phase and the eluate was monitored by a photo-diode array detector. The quantitative analysis was available, when the peak of this sample on HPLC was detected at 290 nm. When this system was applied to commercial health foods, Sildenaˆl was identiˆed and their contents were 25 mg-45 mg/tablet or bottle. These contents nearly correspond to that in Viagra, 25 mg, 50 mg/tablet. Therefore, there is a fear of side eŠects for Sildenaˆl, when it is taken as health foods.

An analog of aildenafil, which is a potent and highly selective inhibitor of phosphodiesterase 5, was found in a dietary supplement marketed for enhancement of sexual function. The compound was isolated by silica gel column chromatography, and its structure was identified by means of 13C-NMR spectrometry, 1H-NMR spectrometry, high-resolution MS, and X-ray structure determination. The compound was identified to be sulfoaildenafil (other names: thioaildenafil, dimethyl sildenafil thione, and thiomethisosildenafil). Sulfoaildenafil is very similar to the compound thiohomosildenafil. As it is difficult to distinguish between them by LC-photodiode array detector analysis, ultra-performance LC (UPLC)/MS, ion trap LC/MS/MS (LC/IT-MS/MS), and GC/MS were performed. The mass spectra of thiohomosildenafil by UPLC/MS and LC/IT-MS/MS showed mass fragments of m/z 58, 72, and 355, and the mass spectrum by GC/MS showed mass fragments of m/z 56, 72, and 420. Some of these fragments had low intensities, but they were useful for distinguishing between the two compounds. The relationship between aildenafil (other names: dimethylsildenafil and methisosildenafil) and homosildenafil is similar to that between sulfoaildenafil and thiohomosildenafil. Therefore, these compounds were also examined.

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