title: All-trans-configuration in Zanthoxylum alkylamides swaps the tingling with a numbing sensation and diminishes salivation.
abstract: The methanol soluble prepared from a supercritical fluid extract of Szechuan pepper (Zanthoxylum piperitum) was screened for its key tingling and numbing chemosensates by application of taste dilution analysis. Further separation of fractions perceived with the highest sensory impact, followed by LC-TOF-MS, LC-MS, and 1D/2D NMR experiments, led to the structure determination of the known alkylamides hydroxy-γ-sanshool (1), hydroxy-α-sanshool (2), hydroxy-β-sanshool (3), bungeanool (4), isobungeanool (5), and hydroxy-γ-isosanshool (6), as well as hydroxy-ε-sanshool (7), the structure of which has not yet been confirmed by NMR, and hydroxy-ζ-sanshool (8), which has not been previously reported in the literature. Psychophysical half-tongue experiments using filter paper rectangles (1 × 2 cm) as the vehicle revealed amides 1, 2, 4, 5, 7, and 8, showing at least one cis-configured double bond, elicited the well-known tingling and paresthetic orosensation above threshold levels of 3.5-8.3 nmol/cm(2). In contrast, the all-trans-configured amides 3 and 6 induced a numbing and anesthetic sensation above thresholds of 3.9 and 7.1 nmol/cm(2), respectively. Interestingly, the mono-cis-configured major amide 2 was found to induce massive salivation, whereas the all-trans-configuration of 3 did not.
authors.affiliation: Chair of Food Chemistry and Molecular Sensory Science, Technische Universität München , Lise-Meitner Strasse 34, D-85354 Freising, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Bader
authors.forename: Timo D
authors.initials: TD
authors.lastname: Stark
authors.forename: Corinna
authors.initials: C
authors.lastname: Dawid
authors.forename: Sofie
authors.initials: S
authors.lastname: Lösch
authors.forename: Thomas
authors.initials: T
authors.lastname: Hofmann
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007536:Isomerism; D008297:Male; D010936:Plant Extracts / Q000737:chemistry* / Q000378:metabolism*; D053284:Polyunsaturated Alkamides / Q000737:chemistry* / Q000378:metabolism*; D012472:Salivation; D013649:Taste; D014059:Tongue / Q000502:physiology; D032106:Zanthoxylum / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010936:Plant Extracts; D053284:Polyunsaturated Alkamides