Phenolic derivatives with an irregular sesquiterpenyl side chain from Macaranga pruinosa.

A stilbene and two flavonoid derivatives, macapruinosins A-C (1-3), together with two known flavonoids, papyriflavonol A and nymphaeol C, have been isolated from the acetone extract of the leaves of Macaranga pruinosa. The structures of these compounds were identified based on spectral data analysis. Compounds 1 and 2 are the first examples of natural compounds containing an irregular sesquiterpenyl side chain with a cyclobutane skeleton.