Studies On Chemical Constituents And Hypolipidemic Effect Of Brassica Rapa L.ssp.Pekinensis

Chinese cabbage(Brassica rapa L.ssp.pekinensis),a Brassica plant belonging to the Cruciferae family,is one of the vegetable crops with the largest cultivated area and the highest yield in China.It occupies an important position in vegetable crops in China.The medicinal records of Chinese cabbage may be found in " Essentials of Diets(Yin Shan Zheng Yao)" of Yuan Dynasty and the " Compendium of Materia Medica(Ben Cao Gang Mu)" in Qing Dynasty.At present,the research of Chinese cabbage mainly focuses on breeding,cultivation,storage and processing etc..In recent years,the chemical research on Chinese cabbage has gradually increased,but further research is still needed to clarify the chemical composition of Chinese cabbage.It has been proved by the modern pharmacological studies that Chinese cabbage has biological activities such as antioxidant,anti-cancer and anti-inflammatory etc..It is also said that the Chinese cabbage with the function of protect the liver and reduce blood lipid levels,but there is no report about the pharmacological effect of Chinese cabbage extract on hypolipidemic as so far.In addition,it is reported that the polyphenols content in the outer leaves of Chinese cabbage was higher than in middle or inner leaves,and the antioxidant capacity of outer leaves was also the strongest.In order to clarify the chemical composition,the nutrients and the functional components of Chinese cabbage,studies on phytochemicals and hypolipidemic effect of Chinese cabbage's outer leaves were performed based on reviewing the research progress of Chinese cabbage.The following innovation results have been achieved:1.Study on chemical constituents of Chinese cabbageBy using some separation techniques,such as silica gel column chromatography,Sephadex LH-20,semi-preparative HPLC,recrystallization and TLC,a total of 25 compounds were isolated from 95% ethanol extract of outer leaves of Chinese cabbage.By physicochemical properties and NMR analysis,17 compounds of them were identified as ?-sitosterol(1),5-hydroxymethylfurfural(2),n-butyl-O-?-Dfructopyranoside(3),(6S,9S)-roseoside(4),uridine(5),succinate(6),methyl succinate(7),p-hydroxycinnamic acid(8),ethyl-?-D-glucopyranoside(9),butyl pyroglutamate(10),cyclo(Tyr-Leu)(11),cyclo(L-Pro-D-Leu)(12),1-chlorohexadecane(13),oleamide(14),stigmastane-3,6-dione(15),cyclo-(L-Leu-L-Ile)(16),(2S)-(3-hydroxy-4-methoxy-2-oxoindolin-3-yl)acetamide(17).A total of 16 components,except for compound 2,were isolated and identified from Chinese cabbage for the first time.Among these 16 components,compounds 3 and 6-17 were isolated and identified from the genus Brassica for the first time.This part of the study enriched the chemical composition of Chinese cabbage and Brassica plants belonging to Cruciferae family.The results could also provided the scientific data for clarifying the chemical composition of Chinese cabbage.2.Study on hypolipidemic effect of Chinese cabbageFor the first time,the study on the effects of n-butanol extract(BE)and water residue part(WRP)of 95% ethanol extract of Chinese cabbage outer leaves on high fat emulsion(HFM)induced hyperlipidemia rats were conducted.The following results have been achieved:Both the high and low dosages(1.5g/kg,0.75g/kg)of WRP could:(1)reduce the total cholesterol(TC)and low-density lipoprotein(LDLC)content,and the levels of aspartate aminotransferase(AST)and alanine aminotransferase(ALT)levels in serum to various degrees,(2)increase the activities of lipoprotein lipase(LPL),hepatic lipase(HL),superoxide dismutase(SOD)and glutathione(GSH)in the liver,and reduce the content of malondialdehyde(MDA),(3)reduce the liver coefficient of hyperlipidemia rats and restore the pathological damage of liver tissue.Furthermore,the high dosage(1.5g/kg)of WRP could also significantly increase the level of high-density lipoprotein(HDLC)in serum.The above results shown that WRP had a good hypolipidemic activity with dose-dependent.Both the high and low dosages(1.5g/kg,0.75g/kg)of BE showed good anti-oxidant effect by significantly increasing SOD and GSH activities,and reducing the MDA level in hyperlipidemia rats' liver.However,BE has no obvious regulation effect on indexes such as liver index,serum lipid,serum transaminase and liver total esterase in hyperlipidemia rats.This part of the study confirmed the hypolipidemic effect and the functional ingredients of Chinese cabbage.Furthermore,theoretical support for expanding the application of Chinese cabbage was also provided.3.Metabolomics study on the hypolipidemic effect of Chinese CabbageBy using metabolomics technology,the mechanism of hypolipidemic effect of WRP was discussed for the first time.A total of 26 potential biomarkers from serum and liver of rats were screened and identified.They are L-tryptophan,glycerophosphocholine,taurocholic acid,prostaglandin G2,taurochenodes oxycholic acid,glycocholic acid,cholic acid,glycochenodeoxycholic acid,phytosphingosine,prostaglandin H2,coprocholic acid,sphinganine,chenodeoxycholic acid,5,6-DHET,3?,7?,12?-trihydroxy-5?-cholestan-26-al,11,12-DiHETrE,sphingosine 1-phosphate,3-dehydrosphinganin,LysoPC(18:1(9Z)/0:0),stearidonic acid,retinyl ester,?-linolenic acid,7?,27-dihydroxycholesterol,7?,26-dihydroxy-4-cholesten-3-one,arachidonic acid,PA(16:0/16:0).The above potential biomarkers were mainly involved in 7 endogenous metabolic pathways:primary bile acid biosynthesis,arachidonic acid metabolism,sphingolipid metabolism,?-linolenic acid metabolism,tryptophan metabolism,glycerophospholipid metabolism and retinol metabolism.Metabolomics studies indicated that the WRP might exert hypolipidemic activity by regulating the above 7 metabolic pathways.The mechanism of hypolipidemic effect of Chinese Cabbage had been discussed.In summary,this thesis systematically studies and discuss the chemical composition and biological activity of the outer leaves of Chinese Cabbage.The research results have enriched the research on the chemical composition and confirmed the hypolipidemic activity of Chinese Cabbage.It provides a scientific reference and theoretical basis for the further development and utilization of Chinese Cabbage.