Codonopilate A, a Triterpenyl Ester as Main Autotoxin in Cultivated Soil of <i>Codonopsis pilosula</i> (Franch.) Nannf

Codonopilate A (<b>1</b>), a triterpenyl ester, was isolated from monocultivated soil of annual <i>Codonopsis pilosula</i> and identified as the main autotoxin. The yield ratio of codonopilate A in dried soil was calculated as 2.04 μg/g. Other two triterpenoids, taraxeryl acetate (<b>2</b>) and 24-methylenecycloartanol (<b>3</b>), were isolated and identified as well showing weaker autotoxity. This was the first time that the potential allelochemicals and autotoxins in the cultivated soil of <i>Codonopsis pilosula</i> were reported. Accumulation of reactive oxygen species (ROS) induced by the autotoxins in the root tips of <i>Codonopsis pilosula</i> was considered as an important factor for the phytotoxic effect. This work systematically investigates the allelopathic and autotoxic effect of <i>Codonopsis pilosula</i>, and the preliminary autotoxic action mode of the three autotoxins. These findings are helpful to understand the molecular mechanism of autotoxicity and conducive to explore proper ways to degrade the autotoxins and eliminate the replanting problems of <i>Codonopsis pilosula</i>

Allelochemicals from the Rhizosphere Soil of Cultivated Astragalus hoantchy

Astragalus hoantchy, a widely cultivated medicinal plant species in traditional Chinese and Mongolian medicine, has been often hampered by replant failure during cultivation, like many other herbs of the genus Astragalus. Root aqueous extracts of Astragalus herbs were reported to exhibit allelopathic activity against other plants and autotoxic activity on their own seedlings, but the allelochemicals released by Astragalus plants have not been specified so far. Ten compounds were isolated from the rhizosphere soil extract of cultivated A. hoantchy and elucidated by spectroscopic analysis. Compounds <b>1</b>–<b>6</b> observably showed allelopathic activity against Lactuca sativa seedlings and autotoxic activity against A. hoantchy seedlings. The isolated compounds were further confirmed and quantified by high-performance liquid chromatography (HPLC) in the rhizosphere soil, with a total concentration of 9.78 μg/g (dry weight). These results specify and verify the allelochemicals released by cultivated A. hoantchy into the soil environment, which may provide new insights into the allelopathic mechanisms of this medicinal plant and probably assist in clarifying the replant problems of Astragalus plants

Cycloartane-type triterpenoids from <i>Astragalus hoantchy</i> French.

<p>A new cycloartane-type triterpenoid, 3β-acetoxy-9β,19-cyclolanost-24<i>E</i>-ene-1α,16β-diol-27-<i>O</i>-β-d-glucopyranoside (<b>1</b>), together with three known ones (<b>2</b>–<b>4</b>) were isolated from the aerial parts of <i>Astragalus hoantchy</i>. The structure of compound <b>1</b> was elucidated by detailed spectroscopic analyses including 1D and 2D NMR, HRESIMS, and IR experiments. All of the four compounds were isolated from <i>A. hoantchy</i> for the first time. The antifungal activities of compounds <b>1</b>–<b>4</b> against a phytopathogenic fungus (<i>Alternaria solani</i>) were evaluated with the result that compound <b>3</b> exhibited a moderate activity with an IC₅₀ value of 284 μg/mL.</p