Advanced NMR-Based Structural Investigation of Glucosinolates and Desulfoglucosinolates

Abstract

Glucosinolates (GLs) constitute a class of plant secondary metabolites that are characteristic of the order Brassicales. They each contain a common hydrophilic moiety connected to a mostly hydrophobic side chain whose constitution is the most frequent structural variant. Their transformations by myrosinases lead to intensively studied and highly reactive compounds of biological relevancy. In other respects, the enzymatic desulfation of GLs produces derivatives (DS-GLs) that are useful for GL analysis. A collection of 31 compounds, GLs and DS-GLs, representing 17 different side chains was established in order to report accurate descriptions of the molecules' H-,C-, and N-NMR parameters. The descriptions of theH-NMR spectra were achieved using the PERCH software, which accurately analyzed the complex coupling patterns that arose from strongly coupled nuclei. The chemical shift assignments were supported by 2D COSY, HSQC, and HMBC spectra. The impact of desulfation and the influence of the nature of the side chains on the chemical shift values are discussed. The results of the spectroscopic analysis and the 3D chemical-structure models of the studied molecules were grouped in structure-and-data-format (SDF) files. The NMR parameters were also collected in a simple text file, a spreadsheet file, and a relational database.

ω-Methylsulfanylalkyl Glucosinolates: A General Synthetic Pathway

“…1 H-NMR (D 2 O) δ 1.67–1.89 (m, 4H, CH 2 ), 2.12 (s, 3H, MeS), 2.61 (t, 2H, J vic = 7.5, H-4′), 2.76 (t, 2H, J vic = 7.5, H-1′), 3.42–3.51 (m, 2H, H-2, H-4), 3.57–3.63 (m, 2H, H-3, H-5), 3.72 (dd, 1H, J 5–6b = 5.8, J gem = 13.1, H-6b), 3.91 (dd, 1H, J 5–6a = 2.7, H-6a), 5.06 (d, 1H, J 1–2 = 10.1, H-1). 13 C-NMR δ 15.2 (MeS), 25.7 (C-2′), 28.2 (C-3′), 31.6 (C-4′), 33.0 (C-1′), 62.2 (C-6), 71.2 (C-4), 73.5 (C-2), 78.7 (C-3), 81.8 (C-5), 83.0 (C-1), 165.4 (C=N) [ 47 ]. HR-ESI-MS: C 12 H 22 NO 9 S 3 : calcd.…”

Glucosinolates: Natural Occurrence, Biosynthesis, Accessibility, Isolation, Structures, and Biological Activities

“…Their qualitative characterization is mainly conducted using liquid chromatography-tandem mass spectrometry ((U)HPLC-MS n ) [ 4 , 96 , 160 ]. Nuclear magnetic resonance (NMR) spectrometry is often used as the ultimate confirmation allowing unambiguous determination of GSL structures [ 4 , 51 ]. Other characterization techniques have been used to complement the previous conventional analytical methods.…”

Doprinos istraživanju glukozinolata (2005. – 2020.)

“…7 Biosinteza brojnih glukozinolata uključuje opsežne promjene u bočnim lancima aglikona, što je posljedica širokog spektra kemijskih promjena poput produljenja lanca, hidroksilacije, O-metilacije, desaturacije, daljnje glikozilacije, oksidacije i aciliranja. 7,8 Tablica 1 -Primjeri biljnih vrsta uspješnih u fitoremedijaciji onečišćujućih tvari 25 ; NMR 17 ; dGL: UV, MS, MS2, MS3, NMR 10,13,17,24 ;…”

“…NIT: GL: UV, IR, MS, NMR 33,34 ; dGL: UV, MS, NMR 35 ; ITC: 17,25,36 ; dGL: UV, MS, MS2, NMR 17,24,26 ; ITC: MS, NMR 27,37 ; NIT: MS, NMR 27,37 [Određena je (R)-konfiguracija. 38 ] 17,25,39 ; dGL: UV, MS, MS2 10,24,26 , NMR 17,40 ;…”