Studies On The Further Isolation Of Insecticidal Component From Periploca Sepium Bunge

The Periploca sepium Bunge(Asclepiadaceae family) is a toxic bine shrub plant widely distributed in China, especially the northern part.Since the 1980 s, Japanese scholars have studied the chemical composition, indicating the active ingredient of the parent structure in Periploca sepium Bunge is C21 steroidal glycosides connected with the polysaccharide.The studies on the further isolation of insecticidal component from Periploca sepium Bunge to get more of the same compound by silica gel column chromatography and preparative HPLC 、bioassay, which will lay the foundation for structure-activity relationship.Periplocoside A, Periplocoside E may become Periplocoside F by chemical modification,What happened to the mixture after the chemical reaction analysis by HPLC.The main results are as follows:1.Five compounds were isolated and their structures were elucidated by spectroscopic methods including 1H-NMR、13C-NMR 、HPLC、ESI-MS.One of them,L2 is a new compound as well as its isomer, a known Periplocoside P, were isolated from the root barks of Periploca sepium. while the other three were reported compounds Periplocoside E、F、T.Bioactivity assay indicated that Periplocoside F、P1、P2、T had Stomach poisoning activities against the 3rd instar larvae of M. separata,the stomach poisoning activity of Periplocoside T is the highest.LC50 values of 48 h against the 3rd instar larvae of M. Separata were 8.06mg/mL、28.02mg/mL、4.37mg/mL、2.19mg/mL.2.Periplocoside A、E(No insecticidal activity)can be turned RA、RE by reaction with sodium methoxide.Structures of RA、RE were elucidated by spectroscopic methods including 1H-NMR、13C-NMR、HPLC、ESI-MS.Their insecticidal activities were evaluated against the 3rd instar larvae of M. separata with the leaf disc method In the same conditions,LC50 values of periplocoside Fwas 8.06mg/mL,LC50 values of RA and RE were more than 80 mg/mL.3. To detect What changes occurred F content in B25 fraction by HPLC external standard method.The results showed that Periplocoside F content in B25 fraction changed dramatically after the reaction,which is 11.3 times the pre-reaction.