Minor dehydrogenated and cleavaged dammarane-type saponins from the steamed roots of Panax notoginseng

Nine new minor dehydrogenated and cleavaged dammarane-type triterpenoid saponins, namely notoginsenosides ST6-ST14 (1-9) were isolated from the steamed roots of Panax notoginseng, together with 14 known ones. Among them, 5-7 and 21-22 were protopanaxadiol type and the left 18 compounds, including 1-4, 8-20, and 23 were protopanaxatriol type saponins. Their structures were identified by extensive analysis of MS, 1D and 2D NMR spectra, and acidic hydrolysis. Resulted from the side chain cleavage, the new saponins 1 and 2 featured in a ketone group at C-25, and 3-5 had an aldehyde unit at C-23. The known saponins 12,16 and 18 displayed the enhancing potential of neurite outgrowth of NGF-mediated PC12 cells at a concentration of 10 mu M, while 20 exhibited acetyl cholinesterase inhibitory activity, with IC50 value of 13.97 mu M. (C) 2015 Elsevier B.V. All rights reserved.