Hydroxyl and methoxyl derivatives of benzylglucosinolate in Lepidium densiflorum with hydrolysis to isothiocyanates and non-isothiocyanate products: substitution governs product type and mass spectral fragmentation
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
A system of benzylic glucosinolates was found and characterized in common pepperweed, Lepidium densiflorum Schrad. The major glucosinolate was the novel 4-hydroxy-3,5-dimethoxybenzylglucosinolate (3,5-dimethoxysinalbin), present at high levels in seeds, leaves, and roots. Medium-level glucosinolates were 3,4-dimethoxybenzylglucosinolate and 3,4,5-trimethoxybenzylglucosinolate. Minor glucosinolates included benzylglucosinolate, 3-hydroxy- and 3-methoxybenzylglucosinolate, 4-hydroxybenzylglucosinolate (sinalbin), the novel 4-hydroxy-3-methoxybenzylglucosinolate (3-methoxysinalbin), and indole-type glucosinolates. A biosynthetic connection is suggested. NMR, UV, and ion trap MS/MS spectral data are reported, showing contrasting MS fragmentation of p-hydroxyls and p-methoxyls. Additional investigations by GC-MS focused on glucosinolate hydrolysis products. Whereas glucosinolates generally yielded isothiocyanates, the dominating 3,5-dimethoxysinalbin with a free p-hydroxyl group produced the corresponding alcohol and syringaldehyde (4-hydroxy-3,5-dimethoxybenzaldehyde). After thermal deactivation of the endogenous myrosinase enzyme, massive accumulation of the corresponding nitrile was detected. This case study points out how non-isothiocyanate glucosinolate hydrolysis products are prevalent in nature and of interest in both plant-pathogen interactions and human health.
Originalsprog | Engelsk |
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Tidsskrift | Journal of Agricultural and Food Chemistry |
Vol/bind | 65 |
Udgave nummer | 15 |
Sider (fra-til) | 3167-3178 |
Antal sider | 12 |
ISSN | 0021-8561 |
DOI | |
Status | Udgivet - 2017 |
ID: 180762874