In vitro and in silico anti-inflammatory effect of minor constituents from the roots of <i>Polygala arillata</i> Buch.-Ham. ex D. Don

Vietnamese traditional medicine has utilised the roots of <i>Polygala arillata</i> Buch.-Ham. ex D. Don to treat acute arthritis, rheumatism, pain, and as a tonic ingredient. In this study, phytochemical analysis of the roots of <i>P. arillata</i> resulted in the isolation of one novel compound, named polygarinolide A (<b>1</b>), along with six known compounds (<b>2</b>-<b>7</b>). High-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) and one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy were among the spectroscopic techniques used to identify their structures. Additionally, the absolute configuration of compound <b>1</b> was determined through ECD calculation. The NO inhibitory activity of purified substances was evaluated. Interestingly, compound <b>2</b> exhibited inhibitory activity on NO production in LPS-stimulated RAW264.7 cells (IC₅₀ = 25.37 μM). Moreover, interactions and binding mechanisms of the most active chemical with cyclooxygenase-2 inhibitor (COX-2) and nitric oxide synthase (iNOS) proteins were investigated by molecular docking simulations. Our findings add to our understanding of the secondary metabolites generated by <i>P. arillata</i> and provide a sound scientific basis for future research into the plant's potential anti-inflammatory properties.