Abietane Diterpenes from Medusantha martiusii and Their Anti-Neuroinflammatory Activity.

Seven new abietane diterpenoids, comprising medusanthol A-G ( 1 - 3 , 5 , 7 - 9 ) and two previously identified analogs ( 4 and 6 ), were isolated from the hexane extract of the aerial parts of Medusantha martiusii. The structures of the compounds were elucidated by HRESIMS, 1D/2D NMR spectroscopic data, IR spectroscopy, NMR calculations with DP4+ probability analysis, and ECD calculations. The anti-neuroinflammatory potential of compounds 1 - 7 was evaluated by determining their ability to inhibit the production of nitric oxide (NO) and the proinflammatory cytokine TNF-α in BV2 microglia stimulated with LPS and IFN-γ. Compounds 1 - 4 and 7 exhibited decreased NO levels at a concentration of 12.5 µM. Compound 1 demonstrated strong activity with an IC 50 of 3.12 µM, and compound 2 had an IC 50 of 15.53 µM; both compounds effectively reduced NO levels compared to the positive control quercetin (IC 50 11.8 µM). Additionally, both compounds significantly decreased TNF-α levels, indicating their potential as promising anti-neuroinflammatory agents.