Intrapilosins I-VII, pentasaccharides from the seeds of Ipomoea intrapilosa.
Purification of a CHCl3-soluble extract from seeds of the Mexican medicinal arborescent morning glory, Ipomoea intrapilosa, by means of preparative-scale recycling HPLC, yielded seven new resin glycosides, intrapilosins I-VII (1-7). Their structures were established through the interpretation of their NMR spectroscopic and FABMS data. All pentasaccharides were found to be macrolactones of the known operculinic acid A with different fatty acids esterifying the same positions: C-2 on the second rhamnose unit and C-3 and C-4 on the third rhamnose moiety. The lactonization site of the aglycon could be placed at C-2 of the second saccharide. The fatty acid components of 1-7 were identified as (+)-(2S)-methylbutanoic, octanoic (caprylic), dodecanoic (lauric), and trans-cinnamic. The less common (-)-(2R)-methylbutanoic acid was also isolated as one of the saponification-liberated residues from intrapilosin IV (4). The presence of the (2R)- and (2S)-methylbutanoyl enantiomers bonded to the same oligosaccharide core in intrapilosins IV (4) and V (5) represents an example of diastereoisomerism due to a chiral esterifying moiety in the resin glycoside mixtures of a morning glory species.
Bah
Moustapha
M
CEACA, Facultad de Química, Universidad Autónoma de Querétaro, Querétaro, Cerro de Las Campanas, 76010, Querétaro, Mexico.
Chérigo
Lilia
L
Taketa
Alexandre T Cardoso
AT
Fragoso-Serrano
Mabel
M
Hammond
Gerald B
GB
Pereda-Miranda
Rogelio
R
D006027:Glycosides / Q000032:analysis; D027741:Ipomoea / Q000737:chemistry*; D008800:Mexico; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D009844:Oligosaccharides / Q000737:chemistry* / Q000302:isolation & purification*; D010946:Plants, Medicinal / Q000737:chemistry*; D012116:Resins, Plant / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D006027:Glycosides; D009844:Oligosaccharides; D012116:Resins, Plant