Gallic Acid from Elaeocarpus floribundus Stem Bark: A Potent Natural Antioxidant with Enzymatic and Pharmacokinetic Validation

Abstract

The present study investigates the antioxidant potential of the stem bark of Elaeocarpus floribundus Blume through an integrated approach involving phytochemical isolation, in vitro radical scavenging assays, ADMET-based safety profiling, and molecular docking. Bioassay-guided fractionation of the ethanolic extract into hexane, chloroform, and ethyl acetate fractions revealed the ethyl acetate fraction to possess the highest antioxidant activity, with an IC50 value of 6.19 μg/mL in the DPPH assay, surpassing that of ascorbic acid (IC50 = 9.74 μg/mL). Subsequent isolation and characterization from the ethyl acetate fraction of the stem bark yielded five known compounds from this plant part for the first time, including gallic acid and epigallocatechin gallate. Both compounds showed potent radical scavenging activity in vitro. Among these, gallic acid exhibited superior pharmacokinetic and safety profiles based on in silico ADMET predictions, no Lipinski’s rule violations, and no predicted toxicity. Molecular docking studies showed that gallic acid had high binding affinities for glutathione reductase (GR) and superoxide dismutase (SOD), exceeding those of their reference inhibitors. A docking analysis further revealed stable interactions with catalytically relevant residues, suggesting a stabilizing modulatory effect on redox homeostasis. These findings identify E. floribundus stem bark as a novel source of antioxidant compounds and highlight gallic acid as a promising therapeutic candidate for oxidative stress-related disorders.