Nonvolatile S-Alk(en)ylthio-l-cysteine Derivatives in Fresh Onion (Allium cepa L. Cultivar)

• Published in: Journal of agricultural and food chemistry Vol. 59; no. 17; pp. 9457 - 9465
• Main Authors: Starkenmann, Christian, Niclass, Yvan, Troccaz, Myriam
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 14.09.2011; Amer Chemical Soc
• Subjects: Agriculture; Agriculture, Multidisciplinary; Allium cepa; bacteria; Biological and medical sciences; Carbon-Sulfur Lyases - metabolism; Chemistry; Chemistry, Applied; Chromatography, High Pressure Liquid; cultivars; Cysteine - analogs & derivatives; Cysteine - analysis; Cysteine - metabolism; Disulfides - metabolism; flavor; Flavors and Aromas/Chemosensory Perception; Food industries; Food Science & Technology; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Fusobacterium nucleatum; Fusobacterium nucleatum - metabolism; Life Sciences & Biomedicine; mouth; Mouth - microbiology; Odorants; off odors; onions; Onions - chemistry; Physical Sciences; Plant Roots - chemistry; propionic acid; Science & Technology; Spectrometry, Mass, Electrospray Ionization; sulfur; Sulfur Compounds - metabolism; Volatile Organic Compounds - metabolism; Fusobacterium nucleatum; Allium cepa L; alk(en)ylthio-l-cysteine; apotryptophanase; alk(en)ylthio-L-cysteine; COMPONENTS; ALLIINASE; SULFIDE; ALLICIN; CYSTEINE SULFOXIDES; CHEMISTRY; GENUS ALLIUM; EXTRACTS; BACTERIAL-POPULATIONS; SUBSTANZEN; Allium cepa; Monocotyledones; Cysteine; Vegetables; Onion; Liliaceae; Aminoacid; Angiospermae; Spermatophyta; Cultivar
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf202082f

The l-cysteine derivatives (R)-2-amino-3-(methyldisulfanyl)propanoic acid (S-methylthio-l-cysteine), (R)-2-amino-3-(propyldisulfanyl)propanoic acid (S-propylthio-l-cysteine), (R)-2-amino-3-(1-propenyldisulfanyl)propanoic acid (S-(1-propenylthio)-l-cysteine), and (R)-2-amino-3-(2-propenyldisulfanyl)propanoic acid (S-allylthio-l-cysteine) were prepared from 3-[(methoxycarbonyl)dithio]-l-alanine, obtained from the reaction of l-cysteine with methoxycarbonylsulfenyl chloride. The occurrence of these S-(+)-alk(en)ylthio-l-cysteine derivatives in onion (Allium cepa L.) was proven by using UPLC-MS-ESI+ in SRM mode. Their concentrations in fresh onion were estimated to be 0.19 mg/kg S-methylthio-l-cysteine, 0.01 mg/kg S-propylthio-l-cysteine, and 0.56 mg/kg (S-(1-propenyllthio)-l-cysteine, concentrations that are about 3000 times lower than that of isoalliin (S-(1-propenyl-S-oxo-l-cysteine). These compounds were treated with Fusobacterium nucleatum, a microorganism responsible for the formation of mouth malodor. These l-cysteine disulfides were demonstrated to predominantly produce tri- and tetrasulfides. Isoalliin is almost entirely consumed by the plant enzyme alliin lyase (EC 4.4.1.4 S-alk(en)yl-S-oxo-l-cysteine lyase) in a few seconds, but it is not transformed by F. nucleatum. This example of flavor modulation shows that the plant produces different precursors, leading to the formation of the same types of volatile sulfur compounds. Whereas the plant enzyme efficiently transforms S-alk(en)yl-S-oxo-l-cysteine, mouth bacteria are responsible for the transformation of S-alk(en)ylthio-l-cysteine.