Abstract

IDENTIFICATION OF β-SITOSTEROL IN A LIPOPHILIC FRACTION OF KHAYA GRANDIFOLIOLA C. DC. (MELIACEAE) BY SPECTROSCOPIC ANALYSIS

Atsain-Allangba Marie Rosine*, Bamba Souleymane, Ouattara Logopho Hyacinthe, Belemlilga Bonewendé Mohamed, Kouamé Oussou Raphaël

Abstract

β-Sitosterol is a widely distributed plant sterol of interest in the phytochemical characterization of natural resources. This study aimed to isolate and spectroscopically characterize a sterol compound from the dichloromethane extract of the stem bark of Khaya grandifoliola C. DC. (Meliaceae), collected in April 2025 in Ahougnassou-Allahou, Tiébissou Department, Côte d’Ivoire. After drying and pulverization, the plant material was subjected to successive maceration with n-hexane, dichloromethane, and ethyl acetate. The dichloromethane extract was then fractionated by silica gel column chromatography, with fractions monitored by thin-layer chromatography (TLC). The isolated compound was characterized by combining proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR), and DEPT-135 spectroscopic data. The 1H NMR spectrum showed an olefinic proton signal at approximately δH 5.35 ppm and a multiplet at δH 3.5-3.6 ppm, consistent with a proton associated with a carbon-carbon double bond and a proton attached to an oxygen-bearing carbon, respectively. The 13C NMR spectrum displayed two olefinic carbon signals at δC 140.8 and 121.7 ppm, together with an oxygenated carbon signal at δC 71.8 ppm. These signals, considered alongside the characteristic aliphatic profile, are consistent with the reported NMR data for β-sitosterol. Accordingly, the spectroscopic findings support the tentative identification of the isolated compound as β-sitosterol. Nevertheless, in the absence of two-dimensional NMR data, mass spectrometric analysis, and an assessment of the isolate’s purity, this structural assignment remains provisional and requires further confirmation.

Keywords: Khaya grandifoliola; β-sitosterol; dichloromethane extract; silica gel column chromatography; NMR spectroscopy; DEPT-135.