title: Applications of direct analysis in real time-mass spectrometry (DART-MS) in Allium chemistry. (Z)-butanethial S-oxide and 1-butenyl thiosulfinates and their S-(E)-1-butenylcysteine S-oxide precursor from Allium siculum.
abstract: Lachrymatory (Z)-butanethial S-oxide along with several 1-butenyl thiosulfinates was detected by DART mass spectrometry upon cutting Allium siculum , a popular ornamental Allium species used in some cultures as a spice. (Z)-Butanethial S-oxide isolated from the plant was shown to be identical to a synthetic sample. Its likely precursor, (R(S),R(C),E)-S-(1-butenyl)cysteine S-oxide (homoisoalliin), was isolated from homogenates of A. siculum, and a closely related species Allium tripedale , and fully characterized. Through use of LC-MS, a series of related gamma-glutamyl derivatives were tentatively identified in A. siculum and A. tripedale homogenates, including gamma-glutamyl-(E)-S-(1-butenyl)cysteine and its S-oxide, gamma-glutamyl-S-butylcysteine and its S-oxide, and gamma-glutamyl-S-methylcysteine and its S-oxide. Because compounds containing the 1-butenyl group have not been previously identified in genus Allium species, this work extends the range of known Allium sulfur compounds. The general applicability of DART mass spectrometry in identifying naturally occurring, thermally fragile thial S-oxides and thiosulfinates is illustrated with onion, Allium cepa , as well as a plant from a different genus, Petiveria alliacea .
authors.affiliation: Department of Applied Chemistry, University of South Bohemia, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic. kubecr@centrum.cz
authors.forename: Roman
authors.initials: R
authors.lastname: Kubec
authors.forename: Robert B
authors.initials: RB
authors.lastname: Cody
authors.forename: A John
authors.initials: AJ
authors.lastname: Dane
authors.forename: Rabi A
authors.initials: RA
authors.lastname: Musah
authors.forename: Jan
authors.initials: J
authors.lastname: Schraml
authors.forename: Abith
authors.initials: A
authors.lastname: Vattekkatte
authors.forename: Eric
authors.initials: E
authors.lastname: Block
mesh_terms: D000490:Allium / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods*; D010087:Oxides / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry
chemical_list: D010087:Oxides; D010936:Plant Extracts