Study Of Chemical Constituents And Antimalarial Activity Of Leptodermis Pilosa Diels

This thesis is composed of three chapters to summarize the research works during the master’s study.Chapter one mainly expounded the studies on the chemical constituents of Leptodermis pilosa Diels.Chapter two primarily elaborated on the study of anti-malarial activities of L.pilosa.The final chapter summarized the research progress on chemical constituents of L.pilosa,as well as the antimalarial activity of Rubiaceae family in which Leptodermis genus was included..Ob Jective: To study the chemical constituents of L.pilosa and their antimalarial activitiy,in order to find out the monomer compound with significant antimalarial activity,and to provide some basis for the development of Leptodermis resources.Methods: The chemical constituents of L.pilosa were isolated and purified by various column chromatography methods(Silica gel,Sephadex LH-20,MCI,HP20),and their structures were identified according to physicochemical properties and modern spectrum analysis techniques.The ma Jor constituent was analyzed by HPLC.The in vivo antimalarial activities of L.pilosa were evaluated by Plasmodium yoelii infected mice model,and the in vitro antimalarial activity was determined by Plasmodium falciparum(3D7 strain)with SYBR Green I staining.Results: Twenty-eight compounds were isolated from the 75% ethanol extract of L.pilosa and identified as paederoside(1),paederosidie acid(2),asperuloside(3),asperuloside acid(4),deacetyl asperuloside(5),deacetyl asperulosidic acid(6),deacetyl asperulosidic acid methyl ester(7),officinaloside G(8),quercetin(9),2R,3R-dihydromyricetin(10),myricetin(11),kaempferol(12),isoquercitrin(13),rutin(14),apiotriboside B(15),oleanolic acid(16),2α-hydroxyloleanolic acid(17),ar Jungenin(18),scopoletin(19),methyl caffeate(20),syringic acid(21),salicylic acid(22),(+)-syringaresinol(23),cleomiscosin C(24),syringaresinol-4’-O-β-D-monoglu-copyranoside(25),daucosterol(26),β-D-fructopyranose(27),and α-D-fructopyranose(28).Twenty-one compounds including 1-8,15 and 17-28 were isolated from genus Leptodermis for the first time,while all compounds were isolated from L.pilosa for the first time.Based on the analysis of HPLC,asperuloside(3)was found to be the main components of L.pilosa with the contents of 0.099% and 0.034% in the plants collected in April and November,while quercetin(9)and myricetin(11)were found to be the main components of the ethyl acetate extract of the 75% ethanol extract of L.pilosa.Accoding to in vivo antimalarial activity experiment,75% ethanol extract of L.pilosa had certain antimalarial activity,and the inhibition rate was 38.12%.The inhibitory rates of the ethyl acetate fraction and water fraction of the 75% ethanol extract of L.pilosa were 51.62% and49.65%.The inhibitory rates of asperuloside(3)were 13.63%,while the inhibitory rates of quercetin(9)and myricetin(11)were 10.50% and 10.90%.Paederoside(1)had the highest in vivo antimalarial activity among the active compounds with an inhibition rate of 25.72%.The compound 3 and 9 combination treat mice could improve the antiplasmodium activity.The results of in vitro activity against human Plasmodium falciparum(3D7 strain)showed that the inhibitory rate of the 75% ethanol crude 75% ethanol extract of L.pilosa was 40.29% at0.3 mg/m L.Conclusion: The chemical components of L.pilosa were complex,and the structural types included iridoids,flavonoids,triterpenes,phenolic compounds,lignans,and steroids,etc,and the main components were iridoids and flavonoids.The results of HPLC analysis showed that asperuloside(3)was the main component of L.pilosa,and the content in the plant was varied with season.The results of in vivo antimalarial activity experiments showed that the ethyl acetate fraction and the water fraction of the 75% ethanol extract of L.pilosa had significant antimalarial activity,with Plasmodium yoelii inhibition rates of 51.62% and49.65%,respectively.On the other hand,since the main component of L.pilosa had a Plasmodium yoelii inhibition rate of 13.63% which were not considered as the active component.The results showed that the high activity of ethyl acetate extract may be the combined action of multiple components.According to in vitro antimalarial studies on Plasmodium falciparum,no compounds showed significant activity,and therefore,further research was needed.