{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T12:07:33Z","timestamp":1772798853726,"version":"3.50.1"},"reference-count":33,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2021,3,13]],"date-time":"2021-03-13T00:00:00Z","timestamp":1615593600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>A highly specific and sensitive proton nuclear magnetic resonance (1H-NMR) method has been developed for the quantification of ephedrine alkaloid derivatives in Ephedra herbal commercial prescriptions. At the region of \u03b4 4.0 to 5.0 ppm in the 1H NMR spectrum, the characteristic signals are separated well from each other, and six analogues in total, methylephedrine (ME), ephedrine (EP), norephedrine (NE), norpseudoephedrine (NP), pseudoephedrine (PE), and methylpseudoephedrine (MP) could be identified. The quantities of these compounds are calculated by the relative ratio of the integral values of the target peak for each compound to the known concentrations of the internal standard anthracene. The present method allows for a rapid and simple quantification of ephedrine alkaloid derivatives in Ephedra-related commercial prescriptions without any preliminary purification steps and standard compounds, and accordingly it can be a powerful tool to verify different Ephedra species. In comparison to conventional chromatographic methods, the advantages of this method include the fact that no standard compounds are required, the quantification can be directly performed on the crude extracts, a better selectivity for various ephedrine alkaloid derivatives, and the fact that a very significant time-gain may be achieved.<\/jats:p>","DOI":"10.3390\/molecules26061599","type":"journal-article","created":{"date-parts":[[2021,3,14]],"date-time":"2021-03-14T23:52:06Z","timestamp":1615765926000},"page":"1599","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["A Rapid and Feasible 1H-NMR Quantification Method of Ephedrine Alkaloids in Ephedra Herbal Preparations"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7666-2420","authenticated-orcid":false,"given":"Hsin-Yi","family":"Hung","sequence":"first","affiliation":[{"name":"School of Pharmacy, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shih-Min","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8319-5768","authenticated-orcid":false,"given":"Chia-Ying","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Applied Chemistry, National Pingtung University, Pingtung 900, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sio-Hong","family":"Lam","sequence":"additional","affiliation":[{"name":"School of Pharmacy, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yu-Yi","family":"Chan","sequence":"additional","affiliation":[{"name":"Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan 710, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Meei-Jen","family":"Liou","sequence":"additional","affiliation":[{"name":"Department of Applied Chemistry, Providence University, Taichung 433, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Po-Chuen","family":"Shieh","sequence":"additional","affiliation":[{"name":"Department of Pharmacy, College of Pharmacy and Health Care, Tajen University, Pingtung 907, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4288-9912","authenticated-orcid":false,"given":"Fu-An","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Pharmacy, College of Pharmacy and Health Care, Tajen University, Pingtung 907, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3019-1138","authenticated-orcid":false,"given":"Ping-Chung","family":"Kuo","sequence":"additional","affiliation":[{"name":"School of Pharmacy, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tian-Shung","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Pharmacy, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan"},{"name":"Department of Pharmacy, College of Pharmacy and Health Care, Tajen University, Pingtung 907, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,3,13]]},"reference":[{"key":"ref_1","unstructured":"Bensky, D., and Gamble, A. 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