Undescribed protolimonoids from the root bark of Dictamnus dasycarpus Turcz

Nine undescribed protolimonoids, including two apotirucallane and seven tirucallane triterpenoids, as well five known compounds, were isolated from the root bark of Dictamnus dasycarpus Turcz. Their structures were elucidated by extensive spectroscopic analysis. Compounds 4-8, with an undescribed 22,25-epoxytirucallene part, were established their absolute configuration by single-crystal X-ray diffraction of 4. Such compounds might provide evidence for the degradation of protolimonoids to limonoids, bridging an oxidative cleavage biogenetic pathway between these structurally diverse triterpenoids. None of them showed anti-inflammatory, hepatoprotective, or monoamine oxidase B inhibitory activity.

Automated summary

Nine undescribed protolimonoids were isolated from the root bark of Dictamnus dasycarpus Turcz, along with five known compounds. Their structures were determined by extensive spectroscopic analysis. Compounds 4-8, featuring an undescribed 22,25-epoxytirucallene part, had their absolute configuration established by single-crystal X-ray diffraction. These compounds might provide evidence for the degradation of protolimonoids to limonoids, bridging an oxidative cleavage biogenetic pathway between these structurally diverse triterpenoids. However, none of them exhibited anti-inflammatory, hepatoprotective, or monoamine oxidase B inhibitory activity.