A new prenylated flavone from Pleione bulbocodioides

A new prenylated flavone, 3,5,7,3'-tetrahydroxy-8,4'-dimethoxy-6-(3-methylbut-2- enyl)flavone (1), together with three known flavone derivatives (2-4), two known dihydrophenanthrenes (5-6), two known lignin derivatives (7-8), and three known phenolic glycoside compounds (9-11) were isolated from the n-BuOH extract of Pleione bulbocodioides. High-resolution electrospray ionization mass spectroscopy (HRESIMS), FTIR spectroscopy, and NMR techniques were used to elucidate the structures of these compounds. Biological investigations showed that compound 5, 4,7-dihydroxy-2-methoxy-9,10-dihydrophenanthrene, exhibited potent anti-inflammatory activity on LPS-stimulated NO production in BV-2 microglial cells, with IC₅₀ value of 5.44 μM.