Resin Glycosides from Ipomoea pes-caprae

Abstract

Ipomoea pes-caprae (beach morning-glory; "riñonina" for the herbal drug in Mexico) is prescribed by traditional healers to moderate "heat" in an infected kidney. The hexane-soluble extract from the aerial parts of this medicinal plant, through preparative-scale recycling HPLC, yielded six new lipophilic oligosaccharides of jalapinolic acid: pescaproside B (1) and pescapreins V-IX (2-6). The previously known pescaproside A (7), pescapreins I-IV (8-11), and stoloniferin III (12) were also identified in the analyzed material by means of HPLC comparison with authentic samples. The glycosidic acid structure for all pentasaccharides was confirmed as simonic acid B. Pescaproside B (1), an acylated glycosidic acid methyl ester, is structurally related to pescaprein III (10). Pescapreins V (2) and VI (3) are diasteroisomeric tetraglycosidic lactones of operculinic acid C. Both of these compounds contain (2S)-methylbutyric and n-dodecanoic acids as their esterifying residues. Pescapreins VII (4) and IX (6) are pentasaccharides that contain an n-decanoyl group as their esterifying fatty acid residue instead of the n-dodecanoyl found in pescapreins I (8) and IV (11). Pescaprein VIII (5) represents an isomer of pescaprein II (9) containing an n-dodecanoyl unit as the esterifying residue at position C-4 of the third rhamnose moiety and a 2-methylpropanoyl at C-2 of the second rhamnose. High-field NMR spectroscopy and FAB mass spectrometry were used to characterize all new isolated compounds.

Characterization of a xylose containing oligosaccharide, an inhibitor of multidrug resistance in Staphylococcus aureus, from Ipomoea pes-caprae

“…The major fractions, rich in low-polarity resin glycosides, were purified by recycling preparative-scale HPLC (Pereda-Miranda and Hernán-dez-Carlos, 2002), resulting in the isolation of nine glycolipids (1-9). These compounds showed similar 1 H and 13 C NMR spectra and displayed diagnostic signals common for the pescaprein series (Escobedo-Martínez and Pereda-Miranda, 2007;Pereda-Miranda et al, 2005). All compounds displayed the same negative-ion FAB-MS fragmentation pattern previously described for related resin glycosides, and the resulting diagnostic peaks were useful to confirm the nature of each of their individual pentasaccharide cores (Escobedo-Martínez and Pereda-Miranda, 2007;Pereda-Miranda et al, 2005).…”

“…These compounds showed similar 1 H and 13 C NMR spectra and displayed diagnostic signals common for the pescaprein series (Escobedo-Martínez and Pereda-Miranda, 2007;Pereda-Miranda et al, 2005). All compounds displayed the same negative-ion FAB-MS fragmentation pattern previously described for related resin glycosides, and the resulting diagnostic peaks were useful to confirm the nature of each of their individual pentasaccharide cores (Escobedo-Martínez and Pereda-Miranda, 2007;Pereda-Miranda et al, 2005). For example, compound 1 afforded a pseudomolecular ion [MÀH] À at m/z 1235 (C 62 H 107 O 24 ) in contrast to the ion at m/z 1249 for its homologue 7 (pescaprein III), indicating a difference of one methylene group between these compounds which resulted from the presence of the aldopentose xylose instead of a methylpentose, e.g., fucose (Zhou et al, 2007).…”

“…This 14 mass unit difference was also observed for all common fragment peaks produced by glycosidic cleavage of each sugar moiety at m/z 1005, 823, 531, and 403 in compound 1. This compound exhibited the initial loss of two esterifying groups at m/z 1151 [MÀHÀC 5 H 8 O] À and 1053 [MÀHÀC 12 H 22 O] À which represented the elimination of one unit of a-methylbutyric acid and one of dodecanoic acid, respectively (Chérigo et al, 2008;Escobedo-Martínez and Pereda-Miranda, 2007;Pereda-Miranda et al, 2005).…”

“…Previous to this investigation, seven pentasaccharides (pescapreins I-IV and VII-IX) and two tetrasaccharides (pescapreins V and VI) of jalapinolic acid were first reported as a result of the chemical analysis of an herbal store sample of this crude drug (Pereda-Miranda et al, 2005;Escobedo-Martínez and Pereda-Miranda, 2007). A Chinese investigation using wild root samples collected in the Hainan province yielded eight new pentasaccharides, pescaprein X-XVII (Tao et al, 2008).…”

“…Departing from this point, the present work was undertaken to emphasize the chemical diversity among the pescaprein series, which indicates their potential to further explore resistance-modifying activity against S. aureus. A wild plant collection was used for this investigation because it showed differences in its resin glycoside composition from that of a commercial sample previously analyzed (Escobedo-Martínez and Pereda-Miranda, 2007;Pereda-Miranda et al, 2005). HPLC isolation of nine pentasaccharides (1-9) from the CHCl 3 -soluble resin glycoside mixture is described herein.…”