EXPLORING THE ANTIOXIDANT POTENTIAL OF FLAVANONES IN STROBILANTHES HAMILTONIANA (STEUD.) BOSSER & HEINE: A COMBINED QUANTUM MECHANICAL, MOLECULAR DOCKING, AND BIOCHEMICAL ASSAY APPROACH

Strobilanthes hamiltoniana (Paalkurinji), a perennial herb of the Acanthaceae family, has traditional use in treating ulcers, diabetes, arthritis, and wounds. S. hamiltoniana leaves were extracted using ethanol, chloroform, and water, and screened for phytochemicals using standard protocols. LC-MS analysis was used to identify flavonoids. Antioxidant activity was evaluated via DPPH, HRS, and  FRAP assays, while anti-inflammatory activity was assessed using the NO scavenging assay. Additionally, DFT (B3LYP/6-311G(d,p)) calculations and molecular docking were performed to investigate interactions with antioxidant-related proteins: monoamine oxidase-B, catalase, cytochrome P450, and NFE2-related factor 2. Based on the DPPH assay, aqueous and chloroform extracts showed 25.74% and 45.94% inhibition, while ethanol and methanol extracts exhibited higher inhibition at 89.10% and 86%. HRS ranged from 25.5% to 86.4%, with ethanol extract showing the highest activity (86.4%) at 300 μg/ml and an IC₅₀ of 25.54 μg/ml. All extracts were effective in the FRAP assay, with ethanol showing the highest activity (79.41%, IC₅₀ = 28.24 μg/ml). In the NO scavenging assay, ethanol again showed the strongest activity (80.41%, IC₅₀ = 26.26 μg/ml). Molecular docking revealed catechin had the strongest affinity for Monoamine Oxidase (−9.869), and also bound well to Cytochrome P450 (−6.399) and Catalase (−6.691). Epigallocatechin also showed strong binding to Monoamine Oxidase (−9.567) and Cytochrome P450 (−8.650). The plant extracts, especially the ethanolic one, showed strong antioxidant and anti-inflammatory activities with favorable IC₅₀ values. These dual properties highlight their potential as therapeutic agents against arthritis, where oxidative stress and inflammation are key factors.