LC–MS guided isolation of ent-kaurane diterpenoids from Nouelia insignis

The preliminary LC–MS investigation on the stems of Nouelia insignis manifested the existence of diterpenoids. As a result, 15 ent-kaurane diterpenoids, including 7 new glycosides (nouelosides A–G, 1–7), were isolated under the direction of LC–MS analysis. The new compounds were determined by extensive spectroscopic analysis including HRESIMS, 1D and 2D NMR data and chemical methods. Compounds 6 and 15 with the exo-methylene cyclopentanone functional group exhibited obvious nitric oxide production inhibitory activity with IC50 values of 3.84 ± 0.20 and 3.19 ± 0.25 μM.

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