title: Revisit to 25R/25S stereochemical analysis of spirostane-type steroidal sapogenins and steroidal saponins via 1H NMR chemical shift data.
abstract: An approach based on the difference (deltaab = deltaa - deltab) between 1H NMR chemical shifts (deltaa, deltab) of the geminal protons of oxymethylene (H2-26) (delta(ab) = < 0.2 for 25R; delta(ab) = > 0.5 for 25S) is proposed for ascertaining 25R/25S orientation of the 27-methyl group for (22R)-spirostane-type steroidal sapogenins and steroidal saponins. These studies suggested the 25R-orientation of the 27-Me group for the steroidal saponins isolated by Temraz et al. from Tribulus alatus.
authors: Natural Product Inc., 7963 Anderson Park Lane, Westerville, OH 43081, USA. pkagrawal@naturalproduct.us
authors: Pawan K
authors: PK
authors: Agrawal
authors: Torsten
authors: T
authors: Burkholz
authors: Claus
authors: C
authors: Jacob
mesh_terms: D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D012502:Sapogenins / Q000737:chemistry*; D013150:Spirostans / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D012502:Sapogenins; D013150:Spirostans