Extraction And Characterization Of The Active Components In Natural Products

With the development of science, the study on the Chinese traditional herbals has attracted a lot of attentions in recent years. The studies on the extraction, separation and characterization of the active components of the herbals have become more and more important. In this thesis, the extraction of ginsenosides and lignans, and the interaction between flavonoids and BSA have been studied.The matrix solid phase dispersion (MSPD) was applied to the extraction of the active components from herbals. The optimized conditions of MSPD were selected and the proposed method was applied to the extraction of ginsenosides and lignans. The reflux extraction was used for comparison. When the diatomaceous earth was used as dispersant, the ratio of sample and dispersant was 1:6, 75% methanol was used as elution and the volume was 9 mL, the extraction yields of Rg1,Re,F3,Rc,Rb2,F1,Rd and F2 obtained by MSPD were 14.20,53.07,5.02,5.19,6.57,3.72,12.20 and 3.55 mg·g-1 and those obtained by reflux extraction were 12.88,50.34,4.82,5.42,6.37,3.80,11.47 and 3.48 mg·g-1. The results indicate that except for the extraction yields of Rc and F1, the recoveries are in the range of 80.23-109.49%. In conclusion, the MSPD method is more appropriat than reflux extraction on the extraction of ginsenosides. The extraction yields of the podophyllotoxin, 4'-demethylpodophyllotoxin, podophyllotoxin and isopicropodophylloneas from the roots of Sinopodophyllum emodi Wall. are 45.45,6.30,14.84 and 0.60 mg·g-1 when the diatomaceous earth was used as dispersant and methanol was used as elution solvent. Therefore, the extraction yields for four lignans obtained by reflux extraction are 32.71,4.47,17.55 and 0.38 mg·g-1. So the MSPD method is better than reflux extraction. In the experimental, when hexane was used as washing agent, the interfering substance was not removed and when the clean-up adsorbent was used, the target compounds can be adsorbed. So the hexane and the clean-up adsorbent were not used.The characterization of the interaction between flavonoids and BSA was studied. The interaction between taxifolin and BSA was also studied. The fluorescence quenching for taxifolin and BSA was static quenching. The binding constants and binding sites were also studied, the values of KA are 2.78×104and 3.76×104 L·mol-1 at 295 K and 310 K, respectively. The effect of temperature on the binding constants is not significant. The numbers of binding sites n are 1.01 and 1.04, in the absence of common ions. The values of KA at 295 K decrease in the presence of the ions Cu2+, Mg2+and Al3+, which means that these ions can weaken the binding between taxifolin and BSA. There is no significant effects on the binding in the presence of F-. But Zn2+, NO3ˉand SO42- can enhance the binding. All the ions can enhance the binding at 310 K. According to values of the thermodynamic parameters, hydrophobic force plays a major role in the interaction. The energy transfer parameters were studied in the absence and presence of some common ions,and the experimental results indicate that these ions almost do not affect on the distance between BSA and taxifolin.Three kinds of flavonoids obtained from the leaves of Actinidia kolomikta(Rupr.et Maxim.)Planch, including kaempferol - 3 - O -α- L - rhamnopyranosyl - (1→3) -α- L - rhamnopyranosyl - (1→6) -β-D-galactopyranoside (drug 1),Kaempfol-7-O-rhamnosyl- 3-O-rutinoside(drug 2) and Kaempferide-7-O-(4″-O- acetylrhamnosyl) -3-O-rutinoside (drug 3), are studied. The static quenching occurs in the interaction between flavonoids and BSA. The binding constants and binding sites were also studied. The binding constants were changed accordance to the following orders, drug 1 > drug 3 > drug 2 at 295 K, which means that drug 1 has the strongest ability to bind with BSA and drug 2 is the weakest. However, at 310 K the binding constants ranked in descending order are as follows: drug 3 > drug 2 > drug 1, which means that the complex formed from drug 3 and BSA is most stable in higher temperature, and the complex formed from drug 1 is weakest. All of these have a great relation with the structure of the flavonoids and the interaction forces between falvanoids and BSA. In the BSA-drug 1 system, hydrogen binding and van der Waals force play a major role, which make the banding constant KA of the reaction of BSA and drug 1 be the largest one in the KA values of three reactions. The result is also related to the structure of drug 1. There are three -OH in ring A and B, so the drug 1 has more opportunities to bind with BSA by hydrogen binding. However, in BSA-drug 2 and BSA-drug 3 system hydrophobic interaction plays an important role, so the values of KA for drug 2 and drug 3 are related to the polarity of flavonoids. It is easy for the flavonoids with low polarity to get close to the hydrophobicity of BSA. It is obviously that the polarity of drug 3 is lower than that of drug 2, so KA of BSA-drug 2 is lower than that of BSA-drug 3. Synchronous fluorescence, three-dimensional fluorescence and CD spectrometry were applied to the investigation of the conformation of BSA. The results were shown that the conformation of BSA was changed in the presence of flavonoids.