Phytochemical on-line screening and in silico study of Helianthemum confertum: antioxidant activity, DFT, MD simulation, ADME/T analysis, and xanthine oxidase binding

Abstract

Seven components from the methanol extract of the aerial part of the endemic species Helianthemum confertum were isolated and identified for the first time. Investigating this species and its separated components chemical make-up and radical scavenging capacity, was the main goal. Using an online HPLC-ABTS˙⁺ test, ORAC, and TEAC assays, the free radical scavenging capacity of the ethyl acetate extract was assessed. The fractionation of these extracts by CC, TLC, and reverse-phase HPLC was guided by the collected data, which was corroborated by TEAC and ORAC assays. Molecular docking studies, DFT at the B3LYP level, and an examination of the ADME/T predictions of all compounds helped to further clarify the phytochemicals' antioxidant potential. Isolation and identification of all components were confirmed through spectroscopy, which revealed a mixture (50–50%) of para-hydroxybenzoic acid 1 and methyl gallate 2, protocatechuic acid 3, astragalin 4, trans-tiliroside 5, cis-tiliroside 6, contaminated by trans-tiliroside and 3-oxo-α-ionol-β-D-glucopyranoside 7, as well as two new compounds for the genus Helianthemum (2 and 7). With a focus on compounds 1, 2, 3, and 4, the results clearly showed that the extract and the compounds tested from this species had a high antioxidant capacity. Within the xanthine oxidase enzyme's pocket, all of the components tested showed strong and stable binding. In light of these findings, the xanthine oxidase/methyl gallate 2 complex was simulated using the Desmond module of the Schrodinger suite molecular dynamics (MD) for 100 ns. Substantially stable receptor–ligand complexes were observed following 1 ns of MD simulation.