Novel ceramides and a new glucoceramide from the roots of Incarvillea arguta

Abstract Novel ceramides, rel‐(3S,4S,5S)‐3‐[(2R) ‐2‐hydroxycosanoyl‐hexacosanoylamino]‐4‐hydroxy‐5‐[(4 Z )‐tetradecane‐4‐ene]‐2,3,4,5‐tetrahydrofuran ( 1a‐g ), and a new glucoceramide, 1‐ O ‐β‐ d ‐glucopyranosyl‐( 2S,3S,4R,8E)‐2‐[(2R) ‐2‐hydroxytetracosanoylamino]‐1,3,4‐octodecanetriol‐8‐ene ( 2 ) were isolated from the aqueous ethanolic extract of the roots of Incarvillea arguta , together with eight known compounds: β‐sitosterol ( 3 ), oleanolic acid ( 4 ), ursolic acid ( 5 ), piperin ( 6 ), maslinic acid ( 7 ), β‐sitosterol 6′‐ O ‐acyl‐β‐ d ‐glucopyranoside ( 8 ), 8‐epideoxyloganic acid ( 9 ), and plantarenaloside ( 10 ). Their structures were elucidated on the basis of spectral data including IR, MS, NMR [ 1 H NMR, 13 C NMR (distortionless enhancement by polarization transfer), 1 H− 1 H COSY, heteronuclear multiplequantum coherence, and heteronuclear multiple‐bond coherence correlations]. The relative configurations were established by nuclear Overhauser effect spectroscopy experiments and by comparison of the NMR spectral data and coupling constants with those already reported in the literature.