Bioactive flavonoids from plant extract of <i>Pyrethrum pulchrum</i> and its acute toxicity

Abstract

<i>Pyrethrum pulchrum</i> Ledeb. has been a phytochemically unexplored Mongolian medicinal folklore plant. In this study, its total flavonoid content was determined and fourteen flavonoids (<b>1-14</b>) were isolated from the aerial parts of <i>P. pulchrum</i>. Their structures were elucidated on the basis of spectroscopic data. The compounds <b>12</b>-<b>14</b>, methoxyflavones, were tested for antiproliferative and cytotoxic activity against A549, HeLa, K-562, THP-1 and HUVEC cell lines. This is the first report on the effects of 5,7,4'-trihydroxy-3,6,3'-trimethoxyflavone (<b>13</b>) against all tested cell lines and it exhibited potent activity against chronic myeloid leukemia K-562 and acute monocytic leukemia THP-1 cells, each with GI₅₀ value at 2.0 μg/mL. The 5,4'-dihydroxy-3,6,7,3'-tetramethoxyflavone (<b>14</b>) showed the most potent activity against THP-1 (GI₅₀ = 1.1 μg/mL) and the highest cytotoxicity (5.6 μg/mL). In addition, acute toxicity of plant ethanol extract was evaluated and the lethal dose (LD₅₀) was estimated at 1048 mg/kg.