Three new sesquiterpenes, namely 3β,11-dihydroxy-4,14-oxideenantioeudesmane (1), 1β,10β,12,14-tetrahydroxy-allo-aromadendrane (2) and 1β,10β,13,14-tetrahydroxy-allo-aromadendrane (3), along with six known sesquiterpenes (4-9), were isolated from the roots of Solanum torvum. Compound 4 and 5 are epimers, their main difference lies in the C-11 configulation. Normally, epimers do not make a huge difference in C NMR spectra, but in this kind of structure of A, B, C rings, and C ring is sterically strained structure, stericall effects influence strongly the (13)C NMR chemical shifts, when C-11 configulation changed, it makes a huge difference in the three ring of structure, such as C-6, C-7, C-11. New compound 2 and 3 are epimers and similar to compound 4 and 5, their just increase a hydroxy in C-1 and have a same regular pattern in C NMR spectra, otherwise, compound 5 was firstly confirmed by single-crystal X-ray diffraction.
Keywords: 13C NMR; Solanum torvum; epimers; sesquiterpenes.