Triterpenoid saponins from the roots of Clematis chinensis Osbeck

A new triterpenoid saponin named clematichinenoside AR₂, along with the six known compounds, was isolated and characterized from Clematis chinensis Osbeck (Ranunculaceae), a commonly used traditional Chinese medicine with anti-inflammatory and anti-rheumatoid activities. The structure of the new saponin was elucidated as 3-O-β-(O-α-l-rhamnopyranosyl-(1 → 6)-O-β-d-glucopyranosyl-(1 → 4)-O-β-d-glucopyranosyl-(1 → 4)-O-β-d-ribopyranosyl-(1 → 3)-O-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosyl)oxy]olean-12-en-21α-hydroxy-28-oic acid-O-α-l-rhamnopyranosyl-(1 → 4)-O-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester (1) by spectral analysis and chemical methods. The effects of two major saponins (clematichinenosides AR and AR₂) on the secretion of TNF-α in murine peritoneal macrophages induced by lipopolysaccharides were further investigated. The result indicated that a majority of triterpenoid saponins of this herb may be useful in the exploration of lead compounds for the treatment of some autoimmune diseases.