Isolation and identification of two novel compounds from Marsdenia roylei and their quantum chemical calculations

Abstract

Two new compounds 1 (Methyl 26-di-deoxy-6-methyl-β-D-allohexopyranoside) and 3 (3, 11, 12, 20 tetra-O-acetyl-pregn-5-ene-14β-ol) have been isolated from the chloroform-soluble extract of the whole plant of Marsdenia roylei (family: Asclepiadaceae) and their structures were determined by 1D, 2D NMR and ESI–MS as well as by chemical modification. We have calculated the molecular geometries, local reactivity descriptors by the density functional theory with B3LYP functional with basis set 6-311G+(d,2p) of 1, 3 and 4 (deacylated 3). The ¹H and ¹³C NMR chemical shifts of 1, 3 and 4 were calculated using Gauge-Including Atomic Orbital approach and these values are correlated with the experimental observations.

Keywords:

• Asclepiadaceae
• Marsdenia roylei
• pregnane derivatives
• spectroscopic analysis
• density functional theory

Acknowledgement

The authors are thankful to Department of Chemistry, University of Lucknow for running the NMR spectra and computational studies.