Two new triterpenoid saponins derived from the leaves of Panax ginseng and their antiinflammatory activity

Abstract

Two novel, minor triterpenoid saponins, ginsenoside LS₁ (<b>1</b>) and 5,6-didehydroginsenoside Rg₃ (<b>2</b>), were isolated from the leaves of <i>P</i>. <i>ginseng</i>. The isolated compounds <b>1</b> and <b>2</b> were assayed for their inhibitory effect on nitric oxide production in LPS-stimulated RAW 264.7 cells, and Compound <b>2</b> showed a significant inhibitory effect with IC₅₀ of 37.38 μM compared with that of NG-monomethyl-L-arginine (IC₅₀ = 90.76 μM). Moreover, Compound <b>2</b> significantly decreased secretion of cytokines such as prostaglandin E₂ and tumor necrosis factor-<i>α</i>. In addition, Compound <b>2</b> significantly suppressed protein expression of inducible nitric oxide synthase and cyclooxygenase-2. These results suggested that Compound <b>2</b> could be used as a valuable candidate for medicinal use or functional food, and the mechanism is warranted for further exploration.