Application of Hansen Solubility Parameters in the Aqueous-Ethanol Extraction of Genistein-7-O-[α-rhamnopyranosyl-(1→6)]-β-glucopyranoside from Derris scandens and Its Molecular Orbital Study on Antioxidant Activity

Abstract

This study explored the extraction of genistein-7-O-[α-rhamnopyranosyl-(1→6)]-β-glucopyranoside (GTG) from Derris scandens using an aqueous-ethanol solvent system, aiming to optimize yield and antioxidant activity. Hansen solubility parameters (HSP) were employed to determine the optimal solvent composition, with the highest GTG yield (6.83 ± 0.06 mg/g dried weight) obtained from 50% ethanol-correlating well with HSP predictions. Ultrasonic extraction was most effective with solvents having a dielectric constant between 50 and 60. The antioxidant potential of isolated GTG was evaluated using the DPPH assay, which yielded an IC₅₀ of 87.86 ± 1.85 μM, and the FRAP assay, with a value of 34.23 ± 2.75 mg FeSO₄ equivalents. Molecular orbital analysis revealed HOMO and LUMO energy gaps (ΔE = 10.6715 eV) similar to known antioxidants such as gallic acid, ascorbic acid, Trolox, and quercetin. These findings demonstrate that HSP effectively guided solvent selection for ultrasound-assisted extraction of GTG. The antioxidant activity is attributed to GTG's capacity to donate electrons and stabilize radicals via extended charge delocalization within the aglycone structure, confirming its potential as a natural antioxidant agent.

Keywords: chromatography; flavonoid; green solvent; polyphenol; solvent selection; validation.

Figure 1

Chemical structure of GTG.

Figure 2

Semi-preparative HPLC chromatogram of the aqueous fraction of Derris scandens water extract, detected at 260 nm.

Figure 3

Characterization of the in-house GTG compound via (A) high-performance liquid chromatography (HPLC) retention time comparison with a reference GTG standard; (B) UV-absorption spectrum comparison with the reference GTG standard; and (C) mass spectrum analysis of the in-house GTG in positive ionization mode.

Figure 4

Calibration curve for GTG.

Figure 5

Chromatograms of aqueous-ethanolic extracts of Derris scandens, detected at 260 nm using UV detection.

Figure 6

The relationship between extracted GTG content, Hansen solubility parameters, and dielectric constants.

Figure 7

The relationship between the concentrations of extracts obtained using various solvents and their % inhibition in the DPPH assay.

Figure 8

Diagrams depicting the frontier molecular orbitals of gallic acid, genistein, GTG, quercetin and Trolox, where the highest occupied molecular orbital (HOMO) is shown in violet/blue colors and the lowest unoccupied molecular orbital (LUMO) is shown in light green/dark green colors.