A Labdane Diterpene from <i>Hedychium coronarium</i> rhizomes: <i>in vitro</i> antimicrobial activity and <i>in silico</i> multi-target docking against <i>Staphylococcus aureus</i> proteins

This study investigated the phytochemical profile and bioactivity of Hedychium coronarium J. Koenig rhizome methanolic extract and an isolated labdane diterpene. Qualitative and quantitative phytochemical analyses confirmed diverse secondary metabolites. FT-IR analysis indicated diverse functional groups, and GC-MS profiling identified 35 compounds in the crude extract. The extract exhibited concentration-dependent antioxidant (IC50 = 100.59 µg/mL) and antimicrobial activities, with the highest zone of inhibition against Staphylococcus aureus (28.73 ± 0.91 mm). Bioassay-guided isolation yielded (E)-Labda-8(17),12-diene-15,16-dial, structurally confirmed by FT-IR, GC-MS, and 1H/1³C NMR. The isolated compound demonstrated enhanced bioactivity at lower concentrations (antimicrobial: 30.40 ± 0.68 mm; antioxidant IC50 = 43.627 µg/mL). Molecular docking against seven Staphylococcus aureus proteins revealed highest binding affinities of −9.46 kcal/mol against dihydrofolate reductase. This integrated study highlights the therapeutic potential of Zingiberaceae rhizomes, combining phytochemical screening, in-vitro bioassays, and in silico modelling to advance the discovery of plant-based drug leads.