NMR-based Structural Classification, Identification, and Quantification of Triterpenoids from Edible Mushroom Ganoderma resinaceum

Ganoderma mushrooms have been widely
used as functional food in China, Japan, and Korea. Ganoderma triterpenoids are deemed to be the main
functional constituents. The structures of Ganoderma triterpenoids are complex but quite similar, which makes their analyses
markedly limited. In this study, we developed a general 2D NMR method
to differentiate Ganoderma triterpenoids,
which classifies them into six types (A–F). Then, by the NMR-based
isolation of A–F type triterpenoids from the fruiting bodies
of G. resinaceum, four new compounds
(1–4) and eight known compounds (5–12) were obtained. Moreover, combined
with spiking experiments in 1D and 2D NMR spectra, compounds 5, 7, and 8, which belong to triterpenoids
of A and B types, were identified. At the end, to achieve a more extensive
application for this NMR method, a qNMR method for the absolute quantification
of 5, 7, and 8 in the gross
triterpenoids from G. resinaceum was
set up. The results showed that this NMR method is reliable for the
NMR-guided isolation and quantification of triterpenoids in G. resinaceum.