| Syringa pinnatifolia var.alashanensis(SP),belonging to the family Oleaceae,is a deciduous shrub with pinnately compound leaves mainly distributed of Alashan,Inner Mongolia and Helan Mountain,Ningxia provinces of China.Its peeled stems,roots,as a Mongolia folk medicine,named "Shan-chen-xiang" in Chinese have the functions on inhibiting Heyi related diseases,clearing heat,relieving pains,attending Heyi-induced heart stirring,heart pain syndrome,blood pain syndrome,and dyspneas,and have been used for the treatment of cardiovascular symptoms and asthma.Previous pharmacological study revealed that essential oils of SP shows a significant protective effect against experimental myocardial ischemia based on the traditional applicaion in clinic.Our current experiments indicated that the ethanol extract of SP also displayed significant protection against myocardial ischemia injuries in rat and mices.Therefore,as a part of systematic research on therapeutic effective substances of SP,a phytochemical investigation on the stem barks and peeled stems was performed.This thesis describes the phytochemical results,including the majority lignans and sesquiterpenoids and minor constituesnt,of stem barks,the non-medicinal part of SP,and the peeled stems,to bring evidence for its traditional therapies and taxonomic disputes.Generally,this thesis is composed of the following sections:The first review section describes a complete summary on the plant origins,taxonomic disputes,phytochemical and pharmacological progress of SP,hopefully to provide reference for full medicinal utilization,clarification of biological effective substance,and drug development.The phytochemistry section,as the major content of this thesis,presents a chemical investigation on the stem barks and peeled stems of SP,respectively,on basis of repeated silica gel,Sephadex LH-20,ODS,preparative TLC,and HPLC methods and extensive spectroscopic data analysis incluing ID,2D NMR,MS,and comparison of their NMR data with those reported in literatures,which led to the isolation and structural determination of a total of 66 constituents.Among which,48 compounds including 14 new ones(numbers With asterisk in the Figure ?)was isolated from stem barks,consisting of 30 lignans and analogs(1-30),six iridoids(31-36),nine phenylethanoids(37-45),and three phenylpropanoids(46-48).A proton NMR-guided fractionation of peeled stems led to the isolation of 18 constituents including ten new ones(numbers with asterisk in the Figure ?),of them seven sesquiterpenes(49-55),six meroterpenoids(56-61),two triterpenoids(62,63),and three miscellaneous compounds(64-66)are included.The structures see Figure ?.The third section is in vitro assays,which describes a few kinds of in vitro assessments,such anti-inflammatory,anti-hypoxia effects in BV-2 and H9c2 cells,cytotoxicity of some of these isolates.In brief,the present study covers a phytochemical research in addition to a preliminary in vitro evaluation on the stem barks and peeled stems of SP.The results reveals that lignans are the main content in stem barks and terpenoids are primary in the peeled stems.There are total 66 compounds including 24 new ones isolated and identified.Among them,28 compounds were isolated in the genus for the first time,and five ones were isolated from the species for the first time.This thesis brings references for illustrating effective ingredients with the antimyocardial ischemia activity of SP and scientific evidences to the taxonomic studies of the genus Syringa.Additionally,the stereochemistry data obtained in this research is expected to provide references for further studies of lignans with all kinds of chiral centers. |
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