Synthesis And Studies On The Preliminary Bioactivities Of Erigeside I And Its Derivatives

Erigeside ( (6-O-caffeoyl-(-D-glucopyranosyl-3-O-(-pyranonoside), a new compound isolated from Erigeron breriscapus(Vant.)Hand-Mazz with substituted cinnamoyl residue attached to the hydroxyl group and 3-hydroxyl-(-pyranone as aglycone, possesses potent antioxidant activity and strong activity of treating apoplexy of brain. In this thesis, the following steps have been carried out on the basis of the total synthesis of Erigeside (.1. The total synthetic routes of Erigeside ( has been investigated. The route started from the reaction of tetraacetyl bromoglucose with 3-hydroxyl-(-pyranone to give the glucoside, then caffeoyl group was attached to the glucoside. The natural glycoside and eleven derivatives which have not been reported before have been synthesized using this method.2. Regioselective protection and selective deprotection have been researched. Acetyl groups were selected for the protection of hydroxyl groups in sugars to obtain the (-anomers of D-glucopyrannoside. It was found that when ethyl chloroformate was employed to protect the two hydroxyls in caffeic acid, the removing of the substituted cinnamoyl and aglycone and oxidation in subsequent reactions could be avoided.3. Selectivity and experimental condition for introducing substituted cinnamoyl to the hydroxy group in the sugar rings have been also studied. Substituted cinnamoyl chloride was a good acylating agent for the esterification of the less sterically hindered hydroxyl groups in the sugar ring and showed good selectivity in the presence of several hydroxyl groups. Using DCC as condencer and substituted cinnamic acid as acylating agent, the acceleration of the reaction was achieved with the employment of DMAP as catalyst. The mechanism of transesterification caused by DMAP in above process was discussed.4. Finally, structure-activity relationships of Erigeside ( and its derivatives have been investigated. The preliminary test in vitro showed that compounds 1, 5, 6, 9, 11 and 12 which possess hydroxyl groups in cinnamoyl had significant activity of anti-oxidation and inhibition effect on the apoptosis induced by hypoxia/reoxygenation, however, the compounds don't possess hydroxyl groups in cinnamoyl didn't show the corresponding activity.