title: Structural determination of sildenafil and its analogues in dietary supplements by fast-atom bombardment collision-induced dissociation tandem mass spectrometry.
abstract: Sildenafil and its analogues, which are used as illegal additives in several dietary supplements, were isolated by liquid-liquid extraction and column chromatography and analyzed by fast-atom bombardment mass spectrometry (FAB-MS). Structures of sildenafil and its derivatives were elucidated by FAB-tandem mass spectrometry (MS/MS) with exact mass measurement in the positive-ion mode. To find structurally diagnostic ions for the sildenafil analogues, authentic sildenafil was preferentially analyzed by high-energy collision-induced dissociation (CID)-MS/MS. The CID-MS/MS spectra of [M+H](+) precursor ions resulted in the formation of numerous characteristic ions via a series of dissociative processes. The product ions formed by CID provided important information on the modification of the piperazine ring, the phenylsulfonyl group and the pyrazolopyrimidine moiety of sildenafil. By interpreting their MS/MS spectra, the chemical structures of sildenafil analogues isolated from dietary supplements could be elucidated and fragmentation patterns were proposed. To clearly identify the sidenafil derivatives in dietary supplements, some of the derivatives such as acetildenafil, homosildenafil and hydroxyhomosildenafil which are not commercially available were synthesized and compared with their MS/MS spectra. In addition, high-resolution mass measurements were conducted to obtain the elemental compositions of sildenafil and its analogues.
authors.affiliation: College of Pharmacy, Kyung Hee University, Seoul 130-701, Korea.
authors.forename: Sungho
authors.initials: S
authors.lastname: Ahn
authors.forename: Joo Yeon
authors.initials: JY
authors.lastname: Hong
authors.forename: Moo Ki
authors.initials: MK
authors.lastname: Hong
authors.forename: Young Pyo
authors.initials: YP
authors.lastname: Jang
authors.forename: Myung Sook
authors.initials: MS
authors.lastname: Oh
authors.forename: Jee H
authors.initials: JH
authors.lastname: Jung
authors.forename: Jongki
authors.initials: J
authors.lastname: Hong
mesh_terms: D019587:Dietary Supplements / Q000032:analysis*; D010879:Piperazines / Q000737:chemistry*; D011687:Purines / Q000737:chemistry; D000068677:Sildenafil Citrate; D016339:Spectrometry, Mass, Fast Atom Bombardment / Q000379:methods; D013450:Sulfones / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods; D014665:Vasodilator Agents / Q000737:chemistry*
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate