Identification and sequencing of sugars in an acetylated saponin of Blighia welwitschii by n.m.r. spectroscopy

Saponins from aerial parts of alfalfa (Medicago sativa)

“…Definitive proof was obtained here through Overhauser effect enhancements. Owing to difficulties in measuring NOE at 300 MHz in mediumsized molecules, rotating frame experiments (ROESY) were performed (Bothner-by et al, 1984;Penders et al, 1989). In every compound that was examined (peracetylated 1-4,2, and 4), ROEs were found between arabinose H-l and H-3, indicating -L-arabinoses in 4Ci conformation but not ruling out the presence of some '€4 conformation isomer (Figure 2).…”