Structural elucidation of glucosides and triterpenes by API-ionspray MS and tandem MS/MS spectrometry

Abstract

API-ionspray MS and tandem MS/MS techniques were utilized to elucidate the structures of eight natural products consisting of lithospermoside and its two acetates, syringin and its two acetates, and two triterpenes-acetyloleanolic acid and methyloleanoate. Lithospermoside, syringin, and oleanolic acid were isolated and identified previously from Thalictrum rugosum (Ranuncularceae), Magnolia grandiflora (Magnoliaceae), and Eugenia javanica Lam. (Myrtaceae), respectively, on the basis of UV, IR ,NMR,MS (EI, CI) and CD data. In this investigation, apparent protonated molecular (MH^+), ammonium-adducted molecular (MNH4^+), and alkali-metal-adducted molecular (MNa^+ and MK^+) ions in the Q1 Scan MS spectra, and prominent as well as diagnostic product ions for structural elucidation in the tandem MS/MS spectra were observed for all investigated natural products each in nanogram quantities of material.