Steroidal glycosides from the seeds of Nicotiana rustica. Structure of rusticoside G

Sephadex gel filtration, absorbtion silica gel chromatography and High Perfomance Liquid Chromatography afforded isolation of individual furostanol glycoside from the methanolic extract of Nicotiana rustica seeds, named by us rusticoside G.

After full acid hydrolysis (25R)-5α-furostan,22-keto,3β,16β,26-triol (rusticogenin) as aglycone, as well as glucose and rhamnose in oligosaccharide chain were identified by the use of physico-chemical methods and analysis of ¹H and ¹³C NMR spectral data. Partial acid hydrolysis and enzymatic splitting produced data on the sequence of sugar moieties. Linkage order and the size of oxygen-containing rings of the monosaccharides were determined after the investigation of the products, received by methylation and methanolysis of permethylated derivative glycoside.

The structure of rusticoside G was established as 3–O-α-L-rhamnopyranosyl-(1→4) –α– L – rhamnopyranosyl – (1→4) –β– D – glucopyranoside – (25R) –5α– furostan, 22-keto, 3β, 16β, 26-triol – [26– O –β– D – glucopyranoside], according to the data of chemical transformations and ¹H and ¹³C NMR spectral analysis. Rusticoside G possesses contraceptive activity.