Bioactivity guided the isolation of extracts from the aerial parts Scutellaria barbata D. Don to discover neo-clerodane diterpenoids with potent phytotoxic activity. Of the 34 isolates, 13 neo-clerodane diterpenoids were described for the first time. The structures of these undescribed compounds were elucidated by extensive analysis of NMR spectroscopic data, and the absolute configurations of scutebarbolides A and L and scutebata W were determined by X-ray diffraction. The phytotoxic activity of all compounds against the growth of the roots and shoots of L. perenne and L. sativa seedlings were first reported, and some compounds showed considerable inhibitory effects, especially scutebarbolide K, whose inhibition rates were higher than those of the positive control at concentrations ranging from 25 to 200 μg/mL. When L. perenne and L. sativa seedlings were treated at a concentration of 200 μg/mL, scutebarbolide K caused wilting symptoms on and finally death of these two tested plant seedlings. In addition, the structure-activity relationships of these neo-clerodane diterpenoids were also discussed.

中文翻译：

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来自黄芩地上部分的植物毒性新克罗丹二萜类化合物

生物活性指导从地上部分 Scutellaria barbata D. Don 中分离提取物，以发现具有强效植物毒性活性的新克罗丹二萜。在 34 个分离株中，首次描述了 13 个新克罗丹二萜。这些未描述的化合物的结构通过对 NMR 光谱数据的广泛分析得到阐明，并且通过 X 射线衍射确定了 scutebarbolides A 和 L 以及 scutebata W 的绝对构型。首次报道了所有化合物对多年生植物和苜蓿幼苗根和枝条生长的植物毒性活性，部分化合物表现出相当大的抑制作用，尤其是绿叶甲壳素K，其抑制率高于阳性对照。浓度范围为 25 至 200 μg/mL。当 L. perenne 和 L. 苜蓿幼苗以 200 μg/mL 的浓度处理，绿叶蒿 K 导致这两种受试植物幼苗出现萎蔫症状并最终死亡。此外，还讨论了这些新克罗丹二萜的构效关系。