New 20(S)-protopanaxadiol type saponins from the leaves of Panax notoginseng and their potential anti-inflammatory activities

Through the combination of various chromatographies, 11 new 20(S)-protopanaxadiol (PPD) type saponins, named as notoginsenosides NL-E₁ - NL-E₄ (1-4), NL-F₁ (5), NL-F₂ (6), NL-G₁ (7), NL-G₂ (8), NL-H₁ - NL-H₃ (9-11) were obtained from the leaves of Panax notoginseng. Their structures were ascertained based on the extensive spectroscopic methods and chemical reactions. Meanwhile, the 20(S)-PPD type saponins with aglycone, (20S,24ζ)-3β,12β,20,24,25-pentahydroxy dammarane, was only found from the leaves of P. notoginseng. The characteristic could be used to distinguish the extracts of P. notoginseng leaves from its other medicinal parts such as roots, rhizomes, flowers or seeds. Furthermore, the nitric oxide (NO) inhibitory activities of all compounds were examined in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. As a result, compounds 2-7, 10 could exert NO inhibitory activity at 25 μM without cytotoxicity. Moreover, the inhibitory activities of them were in dose-dependent manner at 1, 10, and 25 μM. Especially, notoginsenoside NL-F₂ (6) still possessed strong biological activity at 1 μM.

Keywords: 20(S)-protopanaxadiol type saponins; Anti-inflammatory activity; RAW 246.7 cell; The leaves of Panax notoginseng.