Study On The Chemical Constituents And Biological Activities Of Two Species Of Euphorbia From Yunnan

This dissertation is composed of three chapters.Chapter 1 is a review about the structures and bioactivities of diterpenoids with a myrsinane skeleton from the genus Euphorbia since the year of 1995.Euphorbia dracunculoides Lam.and Euphorbia prostrata Ait.,which were collected in Yunnan province,China,have been phytochemically and bioactively studied in chapters 2 and 3,respectively.In chapter 1,128 myrsinane-type diterpenoids reported from the genus Euphorbia since 1995 were summarized.A detailed list of their structures,names,plant sources,biological activities,along with the references were explicitly given in this chapter.In chapter 2,the phytochemical investigation of the the aerial parts of Euphorbia dracunculoides was described.E.dracunculoides,belonging to the genus Euphorbia,is a perennial herb distributed in riverbanks,valleys and roadsides of sandy areas in North Africa,South Europe and Southwest Asia.However,the report of its chemical constituents has not been characterized over the past two decades.By the means of various chromatography methods,such as silica gel,RP-18,MCI,Sephadex LH-20and HPLC,and spectroscopic evidences,72 compounds,including one new diterpene skeleton,29 new diterpenoids and two new triterpenoid glycosides,were obtained from its 70%aqueous acetone extract.Among them,euphordraculolide A?1?is a new carbon skeleton with a?,?-unsaturated-?-lactone moiety,which is derived from a tigliane-type core via a retro-aldol reaction at C-4–C-5,a further oxidation of the aldehyde group,and an intramolecular esterification between C-5 and C-14 in sequence.Euphordraculoin A?2?is a new tigliane,euphordraculoins B and C₁–C₆?3–9?are new lathyranes,and euphordraculoins D–X?10–30?are highly oxidated diterpene esters with a myrsinane skeleton.What's more,compounds 4–9 are the first examples of C-17-glycosylated lathyrane diterpenoids,and compounds 31 and 32 are rare oleanane glycosides with the sugar moiety attached to C-3,of which carbon have not been reported to be rhamnosylated.Meanwhile,40 known compounds?33–72?,involving monoterpenes,diterpenoids,triterpenoids,alkaloids,coumarins,and other phenolic acid derivatives,were also yielded.Among the known isolates,the¹³C-NMR data of 51 were firstly assigned,58 and 59 were firstly reported from plant sources,and compounds 60,61,63–65,and 69 were isolated from the genus Euphorbia for the first time.Some of the diterpenoids and triterpenes were tested for their cytotoxicity against HL-60,SMMC-7721,A-549,MCF-7,and SW480 human tumor cell lines by the MTS method.As a result,two tiglianes?33 and 34?exhibited moderate cytotoxic activities against above five tumor cell lines,with the IC₅₀ values ranging from 8.09 to 34.33?M.In chapter 3,the chemical studies of Euphorbia prostrata were presented.E.prostrata,also known as Pu Di Cao in Fujian province,is also a herbaceous plant in genus Euphorbia,which is mainly distributed in Yunnan,Fujian and some other places in China.As was the case with E.dracunculoides,reports on the phytochemical investigation of E.prostrata were lacking during the past twenty years.With the alternate use of modern chromatography techniques,13 compounds were obtained from the MeOH extract of the whole plant of E.prostrata.The chemical types of the isolates include cerebrosides,monoterpenoids,triterpenoids,anthraquinones,flavonoids and coumarins,etc.All the compounds were isolated from this plant for the first time.