Two new triterpenoids and three 27-nor-triterpenoids were isolated from the stems (with bark) of Nauclea officinalis. Their structures were identified to be 2β,3β,19α,23-tetrahydroxy-urs-12-en-28-oic acid (1), 2β,3β,19α,23-tetrahydroxy-urs-12-en-28-O-[β-D-glucopyranosyl (1-2)-β-D-glucopyranosyl] ester (2), pyrocincholic acid 3β-O-α-L-rhamnopyranoside (3), pyrocincholic acid 3β-O-α-L-rhamnopyranosy 1-28-O-β-D-glucopyranosyl ester (4), pyrocincholic acid 3β-O-α-L-rhamnopyranosy1-28-O-β-D-glucopyranosyl-(1-6)-β-D-glucopyranosyl ester (5) by spectroscopic methods including 1D, 2D NMR and HR-MS analyses. The cytotoxic activity of 1-5 against lung cancer A-549 cells was also investigated.
Keywords: Nauclea officinalis; Rubiaceae; pyrocincholic acid; triterpenoid.