E/Z-Thesinine-O-4'-alpha-rhamnoside, pyrrolizidine conjugates produced by grasses (Poaceae).
Based on direct infusion mass spectrometry we identified a novel alkaloid as a major component of perennial ryegrass (Lolium perenne). Initial mass spectral data suggested it to be a pyrrolizidine conjugate. As this class of alkaloids has not been described before from grasses, we isolated it to elucidate its structure. The isolated alkaloid proved to be a mixture of two stereoisomers. The structures of the two compounds as determined by 1D and 2D NMR spectroscopy, were E-thesinine-O-4'-alpha-rhamnoside (1) and Z-thesinine-O-4'-alpha-rhamnoside (2). These identifications were supported by the characterisation by GC-MS and optical rotation of (+)-isoretronecanol as the necine base released on alkaline hydrolysis of these alkaloids. 1 and 2 together with the aglycone and a hexoside were also detected in tall fescue (Festuca arundinacea). This is the first report of pyrrolizidine alkaloids produced by grasses (Poaceae).
Koulman
Albert
A
AgResearch Grasslands Research Centre, Tennent Drive, Private Bag 11008, Palmerston North, New Zealand.
Seeliger
Claudine
C
Edwards
Patrick J B
PJ
Fraser
Karl
K
Simpson
Wayne
W
Johnson
Linda
L
Cao
Mingshu
M
Rasmussen
Susanne
S
Lane
Geoffrey A
GA
D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009005:Monosaccharides / Q000737:chemistry* / Q000302:isolation & purification; D010936:Plant Extracts / Q000737:chemistry; D006109:Poaceae / Q000737:chemistry*; D011763:Pyrrolizidine Alkaloids / Q000737:chemistry* / Q000302:isolation & purification
D009005:Monosaccharides; D010936:Plant Extracts; D011763:Pyrrolizidine Alkaloids; C531203:thesinine-O-4'-alpha-rhamnoside