Saikosaponins rigidum

From the roots of B. rigidum five new saponins have been isolated and identihed, of which three were saikosaponins, two related to saikogenin F and one to saikogenin D. One of them was also foimd in the aerial parts. Two saponins were related to oleanolic acid. Trivial names of sandrosaponins VII-X wrae given to them. 

The extraction and isolation steps of saikosaponins from aerial parts of B. rigidum are shown in Scheme 1. 

Scheme 1 Extraction and isolation of saikosaponins from B. rigidum... 

Sandrosaponin I (1), the major saikosaponin isolated from the aerial parts of B. rigidum, contained a saikogenin F moiety, first described by Kubata... 

Recently, we have reported the in vivo and in vitro anti-inflammatory activity of two saikosaponins isolated from B. rigidum, budlejasaponin IV and sandrosaponin I, in order to establish the possible real value of these kinds of compounds as anti-inflammatory agents [44]. We showed that saikosaponins inhibited the mouse ear edema induced by topical administration of phorbol myristate acetate (PMA). Saikosaponins, at a dose of 1 mg/ear, significantly inhibited swelling and were as potent as the reference drug indomethacin at 3 mg/ear. These findings were supported by vascular permeability analysis [Table 10 and Fig. (4)]. 

Cyclic sulfites and sulfates in organic synthesis have been reviewed in a Tetrahedron report. The reactions of several carbohydrate-based sulfite and sulfate derivatives with nitrogen, carbon and sulfur nucleophiles are reported. In the area of natural products, five sulfated saikosaponins containing the trisaccharide unit 28 have been isolated as minor constituents from Bupleurum rigidum. The leaf-movement hormones, sulfated phenolic glycosides 29, have been shown to be plant specific, rather than being common to all plants. ... 

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