More Phenolic Derivatives with an Irregular Sesquiterpenyl Side Chain from Macaranga pruinosa

Three new flavonol derivatives, macapruinosins D-F (1-3), together with a known flavonoid glyasperin A, had been isolated from the acetone extract of the leaves of Macaranga pruinosa. The structures of the new compounds were identified based on their spectroscopic data, including UV, IR, 1D and 2D NMR, and HREIMS spectra. Compounds 1 - 2 were further examples of phenolic compounds having an irregular sesquiterpenyl side chain with a cyclobutane skeleton.