Two new phenolic glucosides, hostaflavanone A (1) and anti-1-phenylpropane-1,2-diol-2-O-β-d-glucopyranoside (2), together with six known compounds, anti-1-phenylpropane-1,2-diol (3), phenethyl-O-β-d-glucopyranoside (4), phenethanol-β-d-gentiobioside (5), phenethyl-O-rutinoside (6), (1S, 3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (7), and (1R, 3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (8), were isolated from the flower of Hosta plantaginea, and their structures were elucidated by nuclear magnetic resonance (NMR), high resolution electrospray ionization mass spectroscopy (HRESIMS), and circular dichroism (CD) analyses. The cyclooxygenases (COX-1 and COX-2) inhibition and antioxidant activities of compounds 1 and 4–6 were investigated, and they showed moderate cyclooxygenases inhibition activities. Moreover, only compound 1 exhibited moderate antioxidant activity, with an IC50 value of 83.2 μM, while 4–6 showed insignificant activity with IC50 values of 282, 257, and 275 μM, respectively. This is the first report of compounds 3 and 5–8 from the Liliaceae family. The chemotaxonomic significance of the isolated compounds was also summarized.
