title: Identification and screening of a tadalafil analogue found in adulterated herbal products.
abstract: 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. A positive ion at m/z 404.1644 was detected by LC-Q-TOF/MS, corresponding to a molecular formula of C23H22N3O4. This unknown compound was identified as an analogue of tadalafil containing an additional methylene group and named homotadalafil. Homotadalafil was detected in 10 of 91 herbal products at concentrations of 0.058mgg(-1) to 8.735mgg(-1).
authors.affiliation: Advanced Analysis Team, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong Health Technology Administration Complex, 187 Osongsaengmyeong2-ro, Yeonje-ri, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do 363-700, Republic of Korea.
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Advanced Analysis Team, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong Health Technology Administration Complex, 187 Osongsaengmyeong2-ro, Yeonje-ri, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do 363-700, Republic of Korea.
authors.forename: Hyung Joo
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Advanced Analysis Team, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong Health Technology Administration Complex, 187 Osongsaengmyeong2-ro, Yeonje-ri, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do 363-700, Republic of Korea.
authors.forename: Eunyoung
authors.initials: E
authors.lastname: Noh
authors.affiliation: Advanced Analysis Team, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong Health Technology Administration Complex, 187 Osongsaengmyeong2-ro, Yeonje-ri, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do 363-700, Republic of Korea.
authors.forename: Jung Yeon
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Advanced Analysis Team, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong Health Technology Administration Complex, 187 Osongsaengmyeong2-ro, Yeonje-ri, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do 363-700, Republic of Korea.
authors.forename: So Hyun
authors.initials: SH
authors.lastname: Cho
authors.affiliation: Advanced Analysis Team, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong Health Technology Administration Complex, 187 Osongsaengmyeong2-ro, Yeonje-ri, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do 363-700, Republic of Korea.
authors.forename: Jung-Ah
authors.initials: JA
authors.lastname: Do
authors.affiliation: Advanced Analysis Team, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong Health Technology Administration Complex, 187 Osongsaengmyeong2-ro, Yeonje-ri, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do 363-700, Republic of Korea.
authors.forename: Chang-Yong
authors.initials: CY
authors.lastname: Yoon
authors.affiliation: Advanced Analysis Team, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong Health Technology Administration Complex, 187 Osongsaengmyeong2-ro, Yeonje-ri, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do 363-700, Republic of Korea.
authors.forename: Sooyeul
authors.initials: S
authors.lastname: Cho
authors.affiliation: Advanced Analysis Team, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong Health Technology Administration Complex, 187 Osongsaengmyeong2-ro, Yeonje-ri, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do 363-700, Republic of Korea. Electronic address: kwsh964@korea.kr.
authors.forename: Woo Seong
authors.initials: WS
authors.lastname: Kim
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D029001:Herbal Medicine; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D058986:Phosphodiesterase 5 Inhibitors / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet; D000068581:Tadalafil / Q000031:analogs & derivatives* / Q000032:analysis
chemical_list: D058986:Phosphodiesterase 5 Inhibitors; D000068581:Tadalafil
keywords: Homotadalafil; LC-Q-TOF/MS; NMR; Screening; Tadalafil analogue