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DevelopingDrugsfromTraditional
MedicinalPlants
Overthreequartersoftheworld'spopulationreliesmainlyonplantsandplantextractsforhealthcare．ApproximatelyonethirdoftheprescriptiondrugsintheUScontainplantcomponents，andmorethan120importantprescriptiondrugsarederivedfromplants．Mostofthesedrugsweredevelopedbecauseoftheiruseintraditionalmedicine．Economically，thisrepresents$8000～10，000Mofannualconsumerspending．RecentWorldHealthOrganization(WHO)studiesindicatethatover30percentoftheworld'splantspecieshaveatonetimeoranotherbeenusedformedicinalpurposes．Ofthe250，000higherplantspeciesonEarth，morethan80，000speciesaremedicinal．Althoughtraditionalmedicineiswidespreadthroughouttheworld，itisanintegralpartofeachindividualculture．Itspracticeisbasedmainlyontraditionalbeliefshandeddownfromgenerationtogenerationforhundredsoreventhousandsofyears．Unfortunately，muchofthisancientknowledgeandmanyvaluableplantsarebeinglostatanalarmingrate．Thescientificstudyoftraditionalmedicinesandthesystematicpreservationofmedicinalplantsarethusofgreatimportance．
Forquitealongtime，theonlywaytouseplantmedicineswaseitherdirectapplicationortheuseofcrudeplantextracts．Withthedevelopmentoforganicchemistryatthebeginningofthiscentury，extractionandfractionationtechniquesimprovedsignificantly．Itbecamepossibletoisolateandidentifymanyoftheactivechemicalsfromplants．Inthe1940s，advancesinchemicalsynthesisenabledthesynthesisofmanyplantcomponentsandtheirderivatives．Inwesterncountries，itwasthoughtthatchemicalsynthesisofdrugswouldbemoreeffectiveandeconomicalthanisolationfromnaturalsources．Indeed，thisistrueinmanycases．However，inmanyothercases，syntheticanaloguesarenotaseffectiveastheirnaturalcounterparts．Inadditio，somesyntheticdrugscostmanytimesmorethannaturalones．Inspiredbytheserealisations，coupledwiththefactthatmanydrugswithcomplexstructuresmaybetotallyimpossibletosynthesis，thereisnowaresurgenttrendofreturningtonaturalresourcesfordrugdevelopment．
Importantprescriptiondrugsfromplants
Ephedrineistheoldestandmostclassicexampleofaprescr