In Silico and In Vitro Insights into the Pharmacological Potential of Pouzolzia zeylanica

The present study involves the isolation, structural elucidation, and biological evaluation of eight compounds from Pouzolzia zeylanica. From the n-hexane and ethyl acetate extracts of the plant, eight compounds were successfully isolated and identified: oleanolic acid (1), ursolic acid (2), 2α-hydroxyursolic acid (3), 3β-O-acetyl-12-oleanen-28-oic acid (4), 5-hydroxy-6,7-dimethoxyflavanone (5), 4'-methoxytectochrysin (6), 3,4',5,7-tetrahydroxyflavanone-3-O-L-rhamnopyranoside (7), and 3,3',5,5',7-pentahydroxyflavanone-3-O-L-rhamnopyranoside (8). These compounds were evaluated for in vitro antioxidant activity using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and lipid peroxidation inhibition (TBARS) assays, as well as anti-inflammatory activity via inhibition of nitric oxide (NO) production and the secretion of pro-inflammatory cytokines tumour necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in RAW 264.7 macrophages. It was observed that compound 3 exhibited the strongest antioxidant activity with IC₅₀ values of 18.52 ± 1.50 µM (DPPH) and 10.34 ± 0.93 µM (TBARS), whereas compounds 2, 5, and 6 showed moderate to weak effects. Meanwhile, compound 8 demonstrated the most potent anti-inflammatory effect with IC₅₀ values of 16.25 ± 0.95 µM (NO inhibition), 12.97 ± 0.88 µM (TNF-α inhibition), and 22.52 ± 1.98 µM (IL-6 inhibition). Furthermore, in silico approaches were employed, including density functional theory (DFT) calculations to predict the antioxidant mechanisms of compounds 1 and 3 and molecular docking to assess the cyclooxygenase-2 (COX-2) and phosphodiesterase-4B (PDE4B) inhibitory potentials of compounds 4, 7, and 8. Computational results aligned well with experimental data, supporting the potential of these compounds as natural antioxidant and anti-inflammatory agents.