Alsospinones A and B: Novel flavonoid modulators of CAT/GPX/TrxR with integrated ADMET and molecular modeling

In the relentless pursuit of next-generation antioxidants, we have unveiled two unprecedented flavonoids—alsospinones A (1) and B (2) from the ancient fern Alsophila spinulosa, among which carbon skeleton of compound 2 was reported for the first time. Both compounds demonstrate potent, dose-dependent scavenging of DPPH• radicals (IC₅₀ = 38.13 ± 3.79 and 22.81 ± 1.54 μmol/L). Both new compounds have shown potent antioxidant activity in dose dependent manner against biomarkers including CAT, GSH and MDA. Furthermore, molecular docking and 100-ns dynamics simulations reveal that these scaffolds engage CAT, glutathione peroxidase (GPX), and thioredoxin reductase (TrxR) with exceptional affinities (−13.9 to −18.2 kcal/mol), stabilized by key hydrogen bonds and π–anion contacts to active-site residues (Asp202, Arg203, Asn92, Glu104, Cys–Sec). ADMET profiling confirms their drug-like properties−optimal permeability, minimal cytochrome P450 inhibition, and negligible toxicity risk−especially for 2, which combines high solubility with superior metabolic clearance. Furthermore, this is the first study to describe detailed mechanism and structural insights of both compounds simultaneously: (i) modulate three major antioxidant enzymes (CAT, GPX, TrxR); (ii) reveal a ligand-mediated allosteric relay stabilizing both Cys clusters in TrxR; and (iii) link specific methoxy vs. hydroxyl substitutions to divergent Nrf2 activation and radical-scavenging efficiencies, providing new structure-guided cues for antioxidant drug design.