Structural elucidation of fructose-based carbohydrates isolated from Atractylis aristata n-butanol extract with in vitro and in silico assessment of dual α-amylase inhibition and yeast cytotoxicity

Abstract

This study presents the first detailed structural and biological characterization of fructose-based oligosaccharides Atractylis aristata is a medicinal plant, the saccharide composition of which remains largely uncharacterized. Four saccharides, ranging from mono-to trisaccharides, were isolated from the n-butanol extract and structurally elucidated using 1D and 2D NMR spectroscopy. The identified compounds were β-D-fructofuranoide (S1), β-d-fructopyranosyl-(2 → 1)-d-fructofuranose (S2), β-d-fructofuranosyl-(2 → 1)-α-d-glucopyranoside (Sucrose) (S3), and O-β-d-fructofuranosyl-(2 → 6)-β-d-fructofuranosyl-(2 → 1)-α-d-glucopyranoside (6-kestose) (S4). Biological screening included α-amylase inhibition assays and cytotoxicity evaluation using a yeast (Saccharomyces cerevisiae) model. Among the tested compounds, 6-kestose exhibited the strongest α-amylase inhibitory activity (IC₅₀ = 79.099 μg/mL), surpassing acarbose (IC₅₀ = 155.45 μg/mL), while no cytotoxic effects were observed even at high concentrations. Complementary computational analyses confirmed the stability and reactivity of the saccharides, emphasizing the role of hydroxyl and fructofuranosyl groups in enzyme binding. Frontier molecular orbital and electrostatic potential mapping revealed high molecular stability and well-distributed charge density, while molecular docking and dynamics simulations demonstrated strong and stable interactions of 6-kestose with catalytic residues Asp197 and Glu233. These findings establish A. aristata as a promising and safe natural source of α-amylase inhibitors, offering valuable molecular insights for the future development of antidiabetic agents.