New dammarane-type saponins from the leaves of Panax notoginseng

Two new triterpenoid saponins named notoginsenoside-Ng3 (1) and notoginsenoside-Ng4 (2) along with three known saponins (3–5), were isolated from a water extract of the leaves of Panax notoginseng. Their structures were elucidated by HRESIMS, NMR, X-ray techniques and acid hydrolysis. Moreover, compound 2 was characterized with the conjugated double bonds side-chain, which was rarely found in this plant. The absolute configuration of notoginsenoside Fa (3) with five sugars was confirmed by the single-crystal X-ray diffraction for the first time. Acetylcholinesterase inhibitory activity experiments were also conducted, all the isolated saponins showed weak inhibitory activities in the final concentration of 0.16 mmol/L.