Stereochemistry of a triterpenoid trisaccharide from Centella asiatica. X-Ray determination of the structure of asiaticoside

Abstract

The molecular geometry of asiaticoside (1), a trisaccharide triterpene isolated from Centella asiatica, has been determined by a single-crystal X-ray analysis. The glycoside, C₄₈H₇₈O₁₉, is prismatic with space group monoclinic, C2 and lattice constants a= 41.46 (1), b= 7.563 (4), c= 17.988 (5)Å, β= 99.66(5)°, cell volume V= 5 602.3 ų, and Z= 4. Diffractometer intensity measurements were made with Cu-K_α radiation and least-squares adjustment of the atomic parameters converged to a final R value of 0.073. ¹³C N.m.r. and f.a.b.-m.s. are satisfactorily interpreted within terms of the structure.