Abstract

This study investigated the extracts and bioactive constituents of the aerial parts of Polygonum aviculare L., a well-known traditional medicine for inflammation and diuresis, through bioactivity-guided investigation and molecular docking analysis. Solvent extracts demonstrated significant antioxidant, anti-α-glucosidase, and anti-inflammatory activities, supporting their value for further pharmacological investigation. Among the isolated compounds, gallic acid (1), quercetin (3), myricetin (4), avicularin (6), and isorhamnetin (7) exhibited excellent antioxidant activity in the DPPH assay (SC50 ≤ 6.50 μM) and were stronger than the positive control BHT (SC50 = 36.99 μM). Kaempferol (9) (IC50 of 4.50 µM) demonstrated the highest α-glucosidase inhibition, surpassing that of the clinically used acarbose (IC50 = 519.7 µM). Additionally, gallic acid and quercetin demonstrated significantly stronger NO inhibition than apigenin, while kaempferol showed comparable activity (IC50 = 15.06 ± 1.50 μM vs. 16.08 ± 1.86 μM for apigenin). Molecular docking analyses supported favorable interactions between the active compounds and α-glucosidase and inducible nitric oxide synthase (iNOS). Kaempferol reduced the expression of iNOS and COX-2 in LPS-stimulated RAW 264.7 macrophages and was associated with increased KLF4 and Arg-1 expression and decreased phosphorylation of p38 MAPK and IκBα, suggesting a potential role in promoting an anti-inflammatory M2-like macrophage phenotype. Structure–activity relationship analysis indicated that flavonoid aglycones and specific hydroxylation patterns contribute to the observed biological activities. Collectively, these findings identify quercetin and kaempferol as highly active constituents of P. aviculare and support their potential for further pharmacological investigation.

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