Chemical Constituents of Aerides odorata and Their Anti-Neuroinflammatory Effects on LPS-Activated BV2Microglial...

Comprehensive phytochemical study of the whole plants of Aerides odorata yielded 21 compounds, including two new phenanthrene derivatives (1-2), one new inseparable enantiomeric aurone glycoside (3) and 18 known compounds (4-21). The structures of the new compounds were elucidated by extensive spectroscopic analyses, encompassing NMR, MS, ultraviolet (UV), Fourier transform infrared spectroscopy (FT-IR), optical rotation, and CD data. The anti-inflammatory properties of some isolated compounds were evaluated in lipopolysaccharide activated BV2microglial cells. Among them, gigantol (5), nudol (6), coelonin (9), dihydrocorniferyl dihydro-p-coumarate (10), aerifalcatin (14), and 5-methoxy-9,10-dihydroxyphenanthrene-2,3,7-triol (20) exhibited potent inhibitory activity against nitric oxide production, with IC₅₀ values of 1.82 ± 0.34, 4.88 ± 0.24, 2.42 ± 0.11, 4.67 ± 0.49, 1.37 ± 0.15, and 0.83 ± 0.15 μM, respectively. Furthermore, compounds 6, 10, and 20 significantly attenuated the release of proinflammatory cytokines TNF-α and IL-6 in a concentration-dependent manner. Notably, compound 20 appears to selectively modulate microglia-mediated neuroinflammation via regulation of NF-κB-dependent signaling pathways, leading to decreased production of key pro-inflammatory cytokines.