Three new sesquiterpenes from the stems of <i>Nicotiana tabacum</i> and their bioactivities

<p>Three new sesquiterpenes, methyl 4-isopropyl-7-methoxy-6-methylnaphthalene-1-carboxylate (<b>1</b>)<b>,</b> methyl 2-hydroxy-4-isopropyl-7-methoxy-6-methylnaphthalene-1-carboxylate (<b>2</b>), and methyl 2-hydroxy-6-(hydroxymethyl)-4-isopropyl-7-methoxynaphthalene-1-carboxylate (<b>3</b>), together with three known sesquiterpenes (<b>4</b>–<b>6</b>), were isolated from the stems of <i>Nicotiana tabacum</i>. Their structures were determined by means of HRESIMS and extensive 1D and 2D NMR spectroscopic studies. The results showed that compounds <b>2</b>, <b>3</b>, and <b>5</b> exhibited high anti-TMV activity with inhibition rates of 33.6, 35.8, and 36.7%. Compounds <b>1</b>–<b>6</b> showed weak inhibitory activities against some tested human tumor cell lines (NB4, A549, SHSY5Y, PC3, and MCF7) with IC<sub>50</sub> values in the range of 6.7–9.6 μM.</p>