Conformational Analysis and NMR Data Assignment of Taraxerone Isolated From Cnidoscolus aconitifolius (Chaya)
Year: 2025
Type: article
Abstract: ABSTRACT We report, for the first time, the isolation of taraxerone from an isopropanol extract of chaya ( Cnidoscolus aconitifolius ), a traditional plant used in Mayan culture. Although this natural product has been previously identified in other plant species, the complete assignment of its NMR data had not been accomplished until now. To achieve this, we employed 2D NMR experiments to assign the 1 H and 13 C chemical shifts of taraxerone. Several approaches were used to determine the spin–spin coupling constants ( J H,H ), including GIAO calculations, spin simulation, and dihedral angle analysis via a Karplus‐type HLA equation. Conformational analysis revealed the presence of two conformations of Ring A: a chair and a twisted boat. To better understand the behavior of these conformers, a variable‐temperature 1 H NMR experiment was performed, in which Δ δ /°C values for selected protons were monitored. These changes are attributed to stereoelectronic effects, such as the Perlin effect, as evidenced by 1 J C,H values obtained from HSQC nondecoupled experiments. Isotopomeric shifts ( 1 Δ 12/13 C( 1 H)) were also investigated. All findings were further supported by natural bond orbital (NBO) calculations, which helped explain the observed hyperconjugative interactions.
Source: Magnetic Resonance in Chemistry
DOI: 10.1002/mrc.70055
Language: English
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,440
OpenAlex ID: W4415456775