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