Anti-inflammatory ent-kaurane diterpenoids from the whole plants of Sphagneticola trilobata (L.) Pruski.

Phytochemical investigation of the whole plants of Sphagneticola trilobata (L.) Pruski led to the isolation of thirteen ent-kaurane diterpenoids, including five previously undescribed compounds. Their structures were elucidated through comprehensive spectroscopic data analysis, DP4+ NMR computational calculations, and calculated electronic circular dichroism. All isolated diterpenoids were evaluated for the observed anti-NO production activity in lipopolysaccharide-stimulated RAW 264.7 macrophages. Among them, 16α,17-dihydroxy-ent-kaur-9(11)-en-19-oic acid (6-O-caffeoyl-β-d-glucopyranosyl) ester (4) and 12-oxo-16α,17-dihydroxy-ent-kauran-19-oic acid (5) exhibited significant inhibition on nitric oxide production with IC50 values of 41.5 and 29.1 μM, respectively. Further studies revealed that compounds 4 and 5 exerted anti-inflammatory effects by blocking the nuclear translocation of NF-κB, leading to the downregulation of key inflammatory mediators such as inducible nitric oxide synthase, cyclooxygenase-2, interleukin-1β, and interleukin-6. These findings underscore the potential of these ent-kaurane diterpenoids from S. trilobata as promising lead compounds for the development of anti-inflammatory agents.