Studies On The Structures Of Terpenoids From Five Medicinal Plants

Terpenoids are the largest class of compounds in nature.More than 55,000 terpenoids have been found until now.Terpenoids were found in almost all living organisms,playing important structural and functional roles.The largest sources of terpenoids in nature were plants.Terpenoids could be distributed in every organ in plants,forming essential oil,resin,saponin and phytochrome as important constituents.Many terpenoids had extensive biological activities.Some were related to pathogenic bacteria,such as staphyloxanthin which was found in the staphylococcus aureus.Others had medicinal values,such as santonin,taxol,artemisinin and andrographolide,etc.Terpenoids were also important raw materials for food industry and spice industry.Thus,the research on terpenoids was of great significance in innovative drug development,food additive,and cosmetic industries,etc.Five medicinal plants,Croton mangelong,Euphorbia pekinensis,Homonoia riparia,Sapium discolor,and Eupatorium chinense have been chemically and biologically investigated.As a result,a total of 100 compounds including 77 terpenoids were isolated and elucidated on the basis of extensive spectroscopic methods.30 compounds were new compounds and all the new compounds were terpenoids.Some compounds had been performed bioactivity tests.Thirty-one compounds were isolated from Croton mangelong,including 26 diterpenes(Cm1-Cm26),one sesquiterpene(Cm27),one steroid saponin(Cm28),one lignin(Cm29),one phenethylamine derivative(Cm30),and one tryptophane derivative(Cm31).Compounds Cm1-Cm18 were new chemical structures.(?)-Mangelonoid A and(?)-mangelonoid B(Cm1-Cm4)possessed an unprecedented bicyclo[9.3.1]pentadecane scaffold.Nineteen compounds were isolated from Euphorbia pekinensis,including 18 diterpenes(Ep1-Ep18)and one triterpene(Ep19).Ep1-Ep6 were new compounds.Eighteen triterpenes(Hr1-Hr18)were isolated from Homonoia riparia,including five octanordammaranes(Hr1-Hr4,Hr7),two sesquiterpenes(Hr5 and Hr8),and 11 triterpenes(Hr6?Hr9-Hr18).Hr1-Hr6 were new compounds.Twenty-one compounds(Sd1-Sd21)were isolated from Sapium discolor,including six triterpenes(Sd1-Sd6),two steroids(Sd7 and Sd8),two benzene derivatives(Sd9 and Sd10),four tocopherols(Sd11-Sd14),and seven aliphatic esters(Sd15-Sd21).Eleven compounds were isolated from Eupatorium chinense,including four diterpenes(Ec1-Ec4),three sesquiterpenes(Ec5-Ec7),two steroids(Ec8 and Ec9),and two lignins(Ec10 and Ec11).Moreover,the reported chemical constituents and their bioactivities of the species of the genus Croton and originating in China were reviewed in this thesis.This thesis further enriched the structure of natural terpenoids,especially diterpenes,from natural products.It is expected to provide the basis for synthesis chemistry,pharmacology and new drug screening,and may benefit the utilization and development of traditional Chinese herbal medicine.