Structural and quantitative analysis of Equisetum alkaloids. (August 2015)

• Record Type: Journal Article
• Authors: Cramer, Luise; Ernst, Ludger; Lubienski, Marcus; Papke, Uli; Schiebel, Hans-Martin; Jerz, Gerold; Beuerle, Till
• Is Part Of: Phytochemistry. Volume 116(2015:Aug.)
• Page Start: 269
• Page End: 282
• Publication Date: 2015-08
• Subjects: Equisetum palustre L. -- Equisetaceae -- Equisetum alkaloids -- High performance liquid chromatography–electrospray-tandem mass spectrometry (HPLC–ESI-MS/MS) -- High speed countercurrent chromatography (HSCCC) -- Nuclear magnetic resonance spectroscopy (NMR); Botanical chemistry -- Periodicals; Biochemistry -- Periodicals; Botany -- Periodicals; Chimie végétale -- Périodiques; 572.2
• DOI: 10.1016/j.phytochem.2015.03.003
• Languages: English
• ISSNs: 0031-9422

Abstract

Graphical abstract: Eight alkaloids were detected in Equisetum palustre samples. Besides the known palustrine and N 5 -formylpalustrine, three alkaloids, palustridiene, N 5 - acetylpalustrine, N 5 -formylpalustridiene were structurally elucidated. Highlights: Two new Equisetum alkaloids were fully structurally elucidated. A third alkaloid, N 5 -formylpalustridiene is postulated based on ESI-MS/MS results. 22 Equisetum palustre samples were screened by a new HPLC–ESI-MS/MS method. A set of eight Equisetum alkaloids was detected and quantitated. The alkaloid content and pattern is discussed with regard to origin, season, etc. Abstract: Equisetum palustre L. is known for its toxicity for livestock. Several studies in the past addressed the isolation and identification of the responsible alkaloids. So far, palustrine (1 ) and N 5 -formylpalustrine (2 ) are known alkaloids of E. palustre . A HPLC–ESI-MS/MS method in combination with simple sample work-up was developed to identify and quantitate Equisetum alkaloids. Besides the two known alkaloids six related alkaloids were detected in different Equisetum samples. The structure of the alkaloid palustridiene (3 ) was derived by comprehensive 1D and 2D NMR experiments. N 5 -Acetylpalustrine (4 ) was also thoroughly characterized by NMR for the first time. The structure of N 5 -formylpalustridiene (5 ) is proposed based on mass spectrometry results. Twenty-two E. palustre samples were screened by a HPLC–ESI-MS/MS method after development of a simple sample work-up and in most cases the set of all eight alkaloids were detected in all parts of the plant. A high variability of the alkaloid content and distribution was found depending on plant organ, plant origin and season ranging from 88 to 597 mg/kg dried weight. However, palustrine (1 ) and the alkaloid palustridiene (3 ) always represented the main alkaloids. For the first time, a comprehensive identification, quantitation and distribution of Equisetum alkaloids was achieved.