In Silico Evaluation of Bioactive Compounds Isolated from Scleroderma citrinum Against H1N1 and Acetylcholinesterase: A Post-COVID Perspective

Abstract

Introduction Scleroderma citrinum (syn. Scleroderma aurantium and Scleroderma vulgare) is a mycorrhizal mushroom with known toxic effects but also holds potential for bioactive compound discovery. This study aimed to isolate and identify secondary metabolites from the fruiting bodies of S. citrinum and evaluate their potential antiviral and neuroprotective properties.Materials and Methods The fruiting bodies of S. citrinum were freeze-dried, ground and extracted in CH2Cl2 for 3 days. The extract was filtered, evaporated under vacuum and subjected to successive washing with petroleum ether and Et2O. Chromatographic separation was performed using gradient elution with increasing proportions of ethyl acetate in petroleum ether. Structural elucidation of isolated compounds was achieved via 1D and 2D NMR spectroscopy. Molecular docking analyses assessed the binding affinities of compounds to target enzymes relevant to antiviral and neuroprotective pathways. Selected docked complexes were further evaluated by molecular dynamics simulations (RMSD analysis) and MMGBSA/MMPBSA binding free-energy calculations.Results The chemical investigation resulted in the isolation of the following three compounds: 3,25-dihydroxy-22-acetoxylanosta-8,23-diene, ergosterol, and triacylglycerols. The molecular docking study revealed that 3,25-dihydroxy-22-acetoxylanosta-8, 23-diene exhibited high binding affinities to PARP1 and CDC25B, exceeding that of Tamiflu, suggesting potent antiviral activity. Ergosterol showed superior affinity for PTGS2 indicating potential anti-inflammatory effects. Both have inhibitory potential against Acetylcholinesterase (AChE), surpassing galantamine, thus suggesting neuroprotective effects. Molecular dynamics simulations showed stable protein backbones and ligand behaviors consistent with sustained binding, and MMGBSA/MMPBSA analyses provided complementary energetic support beyond docking scores.Discussion This study isolated and identified 3,25-dihydroxy-22-acetoxylanosta-8,23-diene and ergosterol from Scleroderma citrinum, confirming their structures via comprehensive NMR analyses. Molecular docking revealed strong multi-target binding potential for both compounds, with affinities toward influenza-related proteins (PARP1, CDC25B, PTGS2) and acetylcholinesterase exceeding those of standard drugs such as Tamiflu and galantamine. These results align with previous reports of lanostane triterpenes and ergosterol exhibiting antiviral, anti-inflammatory, and neuroprotective properties. These docking results were further supported by MD stability metrics and MMGBSA/MMPBSA endpoint free-energy analyses. The dual-action profile suggests their promise as lead compounds for therapies addressing both H1N1 influenza and neurodegenerative conditions, warranting further in vitro and in vivo validation.Conclusion Three compounds were successfully isolated from S. citrinum, with molecular docking analyses indicating significant potential as antiviral and neuroprotective agents. The lanostane derivative and ergosterol warrant further biological validation, including in vitro and in vivo studies, to explore their therapeutic applications. Orthogonal MD and MMGBSA/MMPBSA analyses provided additional support for the stability and energetic favorability of the predicted binding modes.