Anti-inflammatory activity via NO production inhibition of compounds from Vietnamese Lycopodium casuarinoides Spring

In our investigation of the methanol extract derived from the aerial parts of Vietnamese Lycopodium casuarinoides Spring, we successfully isolated two novel secondary metabolites: 3 beta,21 alpha,24-trihydroxyserrat-14-en-29-yl-E-4'-hydroxy-3 '-methoxycinnamate (1) and lycocasuarinol A (2), and eight known compounds, namely alpha-onocerin (3), salcolin A (4), salcolin B (5), (2 R,3 R)-dihydrokaempferol (6), apigenin (7), huperzinine (8), 4-methoxycinnamic acid (9), and (E)-p-coumaric acid (10). The structural elucidation of these compounds was accomplished through high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) and one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy techniques. All isolates were tested for their potential to inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 cells. Notably, the flavonoids (2 R,3 R)-dihydrokaempferol (6) and apigenin (7) exhibited significant inhibitory activity against NO production, with IC50 values of 3.4 mu M and 3.0 mu M, respectively. These values surpassed the inhibition observed with the positive control, celastrol. Furthermore, a comparison of the guaiacyl glyceryls salcolin A (4) and salcolin B (5), differing in their threo-beta- and erythro-guaiacyl glyceryl moieties, revealed potential structure-activity relationships. These findings suggest that the extract from Lycopodium casuarinoides and its phytochemical constituents hold promise as potential anti-inflammatory agents