An extract fraction from fruits of Arbutus unedo, L., was cleaned-up by column chromatography and shown by NMR to be a mixture of isomers that resists further attempts at separation by conventional chromatographic methods. High resolution gas chromatography-mass spectrometry (HRGC-MS) confirms the presence of triterpenoid isomers but does not allow separation of all the components. This can be improved by trimethylsilylation but the absence of molecular ions and the complex spectra are difficult to interpret. Complete separation can be achieved by high pressure liquid chromatography (HPLC) coupled to a mass spectrometer by means of a particle beam interface (HPLC-PBMS). Four triterpene compounds are identified through analysis of the corresponding mass spectra: α-amyrin, β-amyrin, and lupeol, have for the first time been identified in Arbutus unedo, L. fruits. A new natural triterpene tentatively identified as olean-12-en-3β,23-diol is described for the first time.
- Arbutus unedo L.
- Particle beam