Phenolic compounds with anti-neuroinflammatory activities from the heartwood of Caesalpinia sappan L. (Sappan Lignum)

Caesappanols G−Q (1−11), eleven undescribed phenolic compounds, including seven homoisoflavans and derivatives (1−7), two protosappanins (8−9), one phenylacylphenol (10), and one chalcone (11), along with nine known compounds (12−20), were isolated from Sappan Lignum, the heartwood of Caesalpinia sappan L. Structural elucidation of these compounds was accomplished through a combination of 1D and 2D NMR spectroscopy, mass spectrometry, NMR calculations, and ECD calculations. Furthermore, the anti-neuroinflammatory potential of these compounds was assessed by measuring their ability to inhibit NO production. All isolated compounds exhibited inhibitory effects on NO production in LPS-induced BV-2 cells. Among them, compounds 18, 19, and 20 demonstrated the most potent activity, with IC₅₀ values of 19.63, 15.84, and 11.01 μM, respectively.