Phytochemical study guided by the myorelaxant activity of the crude extract, fractions and constituent from stem bark of Hymenaea courbaril L.

Ethnopharmacological relevance:Hymenaeacourbaril L. (Caesalpinoideae)isusedinBrazilianfolkmedicine totreatanemia,kidneyproblems,sorethroatandotherdysfunctionsoftherespiratorysystem,suchas bronchitisandasthma,althoughsuchpropertiesareyettobescientificallyvalidated. Aimofthestudy: Inordertogiveascientific basistosupportthetraditionaluseof Hymenaea courbaril, this study wasdesignedtoevaluateantioxidant,myorelaxantandanti-inflammatorypropertiesoftheethanol extractfromstembarkanditsfractions.Themyorelaxanteffectofastilbin,a flavonoidisolatedfromthe bioactiveethylacetatefraction(EAF),hasalsobeenevaluated. Materialandmethods: Inthepresentstudyethanolextractfromstembark(EEHC)andfractionswereanalyzed usingbioassay-guidedfractionation.Thefollowingactivitieswereinvestigated:antioxidantby2,2-diphenyl-1- picrylhydrazyl(DPPH)assay,myorelaxant onrattrachealsmoothmuscle,andanti-inflammatoryusing ovalbumin-inducedleukocytosisandairwayhyperresponsivenessinrats. Results: The resultsofthepresentinvestigationshowthatthewholeextractof Hymenaeacourbaril and someof its fractionsstronglyscavengedDPPHradical.Theextract showedmyorelaxantactivityonrattrachea,beingEAF its highestefficientfraction.Bio-guidedstudyallowedtheisolationofastilbin,awell-known flavonoid.The activityinducedbythiscompoundindicatesthatitmaybe partlyresponsibleforthemyorelaxanteffectofEAF. EAF reducedcontractionsthatdependedondivalentcationinflowthroughvoltage-operatedCa2+ channels (VOCCs) orreceptor-operatedCa2+ channels (ROCCs),butitwasmorepotenttoinhibitVOCC-thanROCC- dependent contractioninducedbyCa2+ additioninACh-enrichedCa2+-freemedium.Oralpretreatmentof antigen-challengedanimalswithEAFpreventedairwayhyperresponsivenessonKCl-inducedcontractionand reducedthenumberoftotalwhitecells,particularlyeosinophilsandneutrophilsinbronchoalveolarlavage. Conclusions: This studyprovidedscientific basisthat Hymenaea courbaril presentspotentialantioxidant, myorelaxantandanti-inflammatoryactions,whichsupportitsuseinfolkmedicinetotreatinflammatory airwaydiseases