Chemical Composition and Anti-Inflammatory Activity of Selaginella tamariscina

Selaginella tamariscina is a traditional Chinese medicine with promising anti-inflammatory activity. In this study, a bioactivity-guided strategy was employed to characterize its active constituents. The ethyl acetate fraction significantly reduced LPS-induced nitric oxide production in RAW264.7 macrophages at 100 µg/mL. UPLC-QTOF/MS analysis tentatively identified seven biflavonoids, including amentoflavone (1), 2,3-dihydroamentoflavone (2), robustaflavone (3), 7″-methoxyrobustaflavone (4), hinokiflavone (5), isocryptomerin (6), and neocryptomerin (7). Among them, five compounds exhibited strong inhibitory activities against both cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). Amentoflavone showed the most potent inhibition, with IC₅₀ values of 2.35 ± 0.05 µM for COX-1 and 5.14 ± 0.16 µM for COX-2. In addition, a validated HPLC method was established for simultaneous quantification. Quantitative analysis of 11 batches revealed pronounced variability in biflavonoid content across different geographical origins, highlighting the necessity of multi-marker quality evaluation. Overall, these results provide insights into the chemical basis, anti-inflammatory activity, and quality evaluation of S. tamariscina.