A new cyclohexenone and two new phenanthrones from <i>Elatostema tenuicaudatum</i>

A new cyclohexenone, 5<i>S</i>-(3,4-dihydroxyphenethyl)cyclohex-2-en-1-one (<b>1</b>), along with two new phenanthrones, (4a<i>S</i>,10a<i>S</i>)- 1,9,10,10a -tetrahydro-4a,6,7-trihydroxy-4(4a<i>H</i>)-phenanthrone (<b>2</b>) and (4a<i>S</i>,10a<i>S</i>)-4a-hydroxy-7-methoxy-1,9,10,10a-tetrahydro-4(4a<i>H</i>)-phenanthrone 6-O-<i>β</i>-D-glucopyranoside (<b>3</b>) were isolated from the whole plant of <i>Elatostema tenuicaudatum.</i> The structures were determined by spectroscopic methods including 1D, 2D NMR and HR-ESI-MS. The absolute configurations of compounds <b>1-3</b> were determined by their experimental and calculated ECD spectral data. The isolates were evaluated for inhibitory activity on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophage cells, and compound <b>2</b> showed the strongest activity with an IC₅₀ value of 9.5 ± 1.2 μM.