Structural analysis of unusual alkaloids isolated from Narcissus pseudonarcissus cv. Carlton

Jana Křoustková; Aneta Ritomská; Abdullah Al Mamun; Daniela Hulcová; Lubomír Opletal; Jiří Kuneš; Lucie Cahlíková; Franz Bucar

doi:10.1016/j.phytochem.2022.113439

Structural analysis of unusual alkaloids isolated from Narcissus pseudonarcissus cv. Carlton

Phytochemistry. 2022 Dec:204:113439. doi: 10.1016/j.phytochem.2022.113439. Epub 2022 Sep 21.

Authors

Jana Křoustková¹, Aneta Ritomská², Abdullah Al Mamun², Daniela Hulcová², Lubomír Opletal², Jiří Kuneš³, Lucie Cahlíková², Franz Bucar⁴

Affiliations

¹ ADINACO Research Group, Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, 500 05, Hradec Kralove, Czech Republic; Institute of Pharmaceutical Sciences, University of Graz, Beethovenstraße 8, 8010, Graz, Austria. Electronic address: marikoj2@faf.cuni.cz.
² ADINACO Research Group, Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, 500 05, Hradec Kralove, Czech Republic.
³ Department of Bioorganic and Organic Chemistry, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, 500 05, Hradec Kralove, Czech Republic.
⁴ Institute of Pharmaceutical Sciences, University of Graz, Beethovenstraße 8, 8010, Graz, Austria.

PMID: 36152726
DOI: 10.1016/j.phytochem.2022.113439

Abstract

Narciindole A, the first representative of Amaryllidaceae alkaloids with an indol-3-ylmethanone framework, was isolated from bulbs of Narcissus pseudonarcissus (L.) cv. Carlton, together with carltonine D and carltonine E, which share the same unusual structural motif as dimeric carltonine C (reported in 2020), exhibiting atropisomerism. Unambiguous structure elucidations have been achieved by NMR spectroscopy, HRMS, and comparison with literature data of related alkaloids. Furthermore, the chirality of known alkaloids with a galanthindole biaryl core was revised using optical rotation. Last, but not least, a biosynthetic pathway for dimeric carltonine-type alkaloids was proposed. Unfortunately, in terms of biological activity, the isolated alkaloids showed only moderate inhibition of human acetylcholinesterase and/or butyrylcholinesterase.

Keywords: Alkaloids; Alzheimer's disease; Amaryllidaceae; Atropisomerism; Carltonines; Narcissus pseudonarcissus (L.) cv. Carlton; Specific rotation revised; Structure elucidation.