The structures of saikosaponin-E and acetylsaikosaponins, minor components isolated from Bupleurum falcatum L., determined by C-13 NMR spectroscopy

✍ Scribed by Hiroshi Ishii; Shujiro Seo; Kazuo Tori; Takehiko Tozyo; Yohko Yoshimura

• Publisher: Elsevier Science
• Year: 1977
• Tongue: French
• Weight: 273 KB
• Volume: 18
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)92982-x

✦ Synopsis

We report here a successful example of organic structure determination whichrequires several steps of chemical procedure and has readily been performed using 13C NMR spectroscopy without chemical degradations. Triterpenoid glycosides, saikosaponin-a (3, -b,--b,, -c, -d (2, and -f were already isolated from the methanolic extract of Bupleurum falcatum L. and their structures had been determined in this laboratory. I-3 In connection with useful biological activities of this kind of saponins, we searched for minor components of B. falcatum and isolated seven saponins (L, 3 5, 5, z, x, and 9 from the frac--tions with Rf values higher than those of the known saponins (see TABLE 1). Their 100-MHz 'H NMR spectra in pyridine-ds revealed that five of them, 3_, ,4, 5, z, and 9_, have one OAc and six angular Me groups, and that ,I_ has seven angular Me groups and 2 only two angular Me groups (bH 0.60 and 0.74). Recently, Tanaka and coworkers5 and we3 demonstrated that 13C NMR spectroscopy is a potential tool for elucidating structures of natural plant glycosides which are unstable against acid hydrolysis, provided