Rev. bras. farmacogn. vol.25 número3

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w w w. s b f g n o s i a . o r g . b r / r e v i s t a

Original

Article

Antinociceptive

and

antiulcer

activities

of

Pycnanthus

angolensis

Margaret

Oluwatoyin

Sofidiya

∗

_,

_Adepero

_Olubukola

_Awolesi

DepartmentofPharmacognosy,FacultyofPharmacy,UniversityofLagos,Nigeria

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r

t

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c

l

e

i

n

f

o

Articlehistory:

Received20September2014 Accepted13May2015 Availableonline16June2015

Keywords:

Pycnanthusangolensis

Myristicaceae Ethanolicextract Antinociceptive Antiulcer

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Pycnanthusangolensis(Welw)Warb.,Myristicaceae,isusedinNigeriafolkmedicinetotreatcomplaints suchastoothache,headache,sorethroat,ulcersandwounds.Theaimofthestudywastoinvestigate theantinociceptiveandantiulceractivitiesofthestembarkextractofPycnanthusangolensis.Acute tox-icitywasconductedwithasingleoraldoseof5g/kg.Antinociceptiveactivitywasevaluatedinacetic acid-inducedwrithing,formalinandtailimmersiontestsinmicewhileantiulceractivitywasevaluated inethanolandindomethacin-inducedmodelsinrats.Inaceticacid-inducedwrithingtest,theextract (50,100and150mg/kg,p.o.),significantlyreducedthenumberofwrithes(46.75%,57.28%and75.69%) respectively,comparedtocontrol.Theextractsignificantly(p<0.001)reducedthetimespentinlicking thehindpawatbothphases,informalintest.Intailimmersiontest,significantantinociceptiveeffect wasonlyobservedwiththedoseof150mg/kg,withpeakeffectat90min(43.38%).Thereisnosignificant changeinthespontaneouslocomotoractivityofanimalsintheopenfield.Theextractpreventedthe gas-triculcerationcausedbyethanolandindomethacintreatmentscomparedtocontrol.Theresultsshowed thatP.angolensisextractpossessesantinociceptiveandantiulceractivitiessupportingthetraditionaluse forrelievingpainandulcers.

Introduction

Painhasbeenofficiallydefinedasanunpleasantsensoryand emotionalexperience associatedwithactual orpotentialtissue damageordescribedintermsofsuchdamage(IASP,1994).Itis adisablingaccompanimentwhichinmanycasesrepresentsthe onlysymptomforthediagnosisofseveraldiseases.Inrelieveof pain,classicalanalgesicdrugsnotablyopiatesand non-steroidal anti-inflammatorydrugs (NSAID)are used(García etal., 2011). TheuseofthesedrugsespeciallyNSAIDis consideredtobethe majorriskfactoringastriculcers.Inthiscontext,focusonplant researchhasincreasedworldwideandseveralstudieshadshowed immensepotentialofmedicinalplantsasalternativeremediesin themanagementofpainandgastriculcers.

Pycnanthusangolensis(Welw)Warb.,Myristicaceae,commonly knownas ‘Africannutmeg’ or ‘false nutmeg’, isused in a vari-etyofherbalrecipesforthetreatmentofchestpain, headache, various skin diseases and gastrointestinal ailments in Nigeria

(Omobuwajoetal.,1992;Oladimejietal.,2006).Theplantcontains

avarietyofchemicalconstituents,suchasallantoin(Pristaetal., 1960),kombicacid(Loketal.,1983),isoflavones-7,4′

-dimethoxy-2′ _{hydroxylisoflavone}_and₂′_{-hydroxyformononetin}₍_Omobuwajo

∗ Correspondingauthor.

E-mail:msofidiya@unilag.edu.ng(M.O.Sofidiya).

etal.,1992),dihydroguaiaceticacid(Njokuetal.,1997), pycnanthu-quinoneAandB(Fortetal.,2000)andpycnanolideAandB(Onocha

andAli,2011).

BiologicalactivitiesofP.angolensisreportedinliteratureinclude antihelmintic (Gbolade and Adeyemi, 2008), anticancer (Njoku etal.,1997),antihyperglycemic(Luoetal.,1999;Fortetal.,2000), cytotoxicityandantileishmanialactivities(Onochaetal.,2008).The planthasalsobeenscreenedbyanumberofauthorsformalariaand antimicrobialactivities,withprovenefficacy(Ancolioetal.,2002;

Oladimejietal.,2006;Abrantesetal.,2008;OnochaandOtunla,

2010).Agyareetal.(2009),inanattempttoinvestigatethe

antiul-cerpotentialoftheplantscreenedthestembarkextractagainst

Helicobacterpylori.Asidethesereportsandtothebestofour knowl-edge,thepharmacologicaleffectoftheplantonpainfulprocesses andgastrointestinalsystemhasnotbeenreported.Therefore,the objectiveofthestudywastoinvestigatetheantinociceptiveand antiulcer properties of theethanolic extract of P. angolensis in experimentalanimalmodels.

Materialsandmethods

Plantmaterial

ThestembarkofPycnanthusangolensis(Welw)Warb., Myris-ticaceae, was collected from Olokemeji forest, Ibadan (7◦₂₅′_N,

3◦₃₁′_E),_Oyo_State,_Nigeria_in_February,₂₀₁₁_and_{authenticated}_by

http://dx.doi.org/10.1016/j.bjp.2015.05.004

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Mr.T.K.OdewoattheherbariumunitoftheDepartmentofBotany, UniversityofLagos,Lagos,Nigeria.Voucherspecimen(LUH4588) wasdepositedintheherbarium.

Extractionprocedure

Thestembarkwascutintopiecesanddriedatroom tempera-tureforthreeweeks.Theairdriedmaterial(500g)waspowdered usingChristyandNorriis8′_Lab_Milling_Machine_(serial_No.₅₀₁₅₈₎

andextractedtwicebymacerationwith95%ethanol(3l)atroom temperaturefor48h.Thecombinedethanolicextractwasfiltered withdouble-layeredmuslinclothandconcentratedonawaterbath at45◦_C_to_yield_a_{reddish-brown}_solid_(1.32%,_w/w).

Animals

MaleAlbinoWistarrats(130–150g)wereobtainedfroma pri-vatevendor,ResearchEnterprise,Ibadan,Nigeria.Theanimalswere maintainedunderstandardlaboratoryconditionsinthe Labora-toryAnimalCentreoftheCollegeofMedicine,UniversityofLagos, Lagos,Nigeria.Theanimalswerekeptincagesattheroom temper-atureandfedwithfoodandwateradlibitum.Theywereallowed toacclimatizefortwoweeksbeforethecommencementof exper-imentalprocedures.Theexperimentalproceduresadoptedwere inaccordancewiththeprovisionsoftheExperimentationEthics CommitteeonAnimalUseoftheCollegeofMedicine,Universityof Lagos,Lagos,Nigeria(CM/COM/08/VOL.XXV)andtheUnitedStates NationalAcademyofSciencesGuidefortheCareandUseof Labo-ratoryAnimals(NIH,1985).

Acutetoxicity

Theacutetoxicity studyof P.angolensiswasperformedin a singleoraldoseadministrationof5000mg/kgtosevenmalemice

(Jaijoyetal.,2010).Micewerefastedfor12hbeforethe

adminis-trationoftheextract.Behavioralparametersincludingconvulsion, hyperactivity,sedation,grooming,increasedordecreased respira-tionwereobservedfor,overaperiodofsevendays.

Antinociceptivestudies

Aceticacid-inducedwrithingtest

The acetic acid-induced writhing test was done as previ-ouslydescribedbyArslanetal.,2010.Theextract(50,100and 150mg/kg),distilledwater(10ml/kg)andacetylsalicylicacid(ASA, 100mg/kg),wereadministeredorallytoeach groupofmice1h beforeintraperitoneal injectionwith0.6%acetic acid(10ml/kg, body weight) to induce writhings. The number of abdominal constrictionswithstretchingofthehindlimbswascounted cumu-lativelyoveraperiodof30min.Thepercentageofinhibitionofthe numberofwrithingswasthencalculated.

Formalintest

ThemethodusedwasaspreviouslydescribedbyGomesetal.

(2007),withslightmodification.Twentymicrolitersofformalin

(1%,v/v)wasinjectedsubcutaneouslyintotherighthindpawof mice.Thetime(insecond)spentinlickingandbitingoftheinjected pawwastakenasanindicatorofpainresponse.Responseswere measuredfor5min(firstphase) and15–30min(secondphase) afterformalininjection.Theextract(50,100and150mg/kg,p.o.), distilledwater(10ml/kg,p.o.)andmorphine(3mg/kg,s.c.)were administered60and30min,respectively,beforeformalin injec-tion.

Tailimmersiontest

Priortotheexperiment,theanimalswerescreenedfora sen-sitivitytest.Themousewasgentlyhandledandonethirdofthe tailwasimmersedintoawaterbathsetat55±1◦_C₍_Agrahari_et_al.,

2010).Themicewhichwithdrewthetailwithin5swereselected foractivity.Eachanimalservedasitscontrol.Thereactiontime forthesamegroupwastakenatintervals60,90,120,and150min afteralatencyperiodoflhfollowingtheoraladministrationof theextractatthedoseof50,100and150mg/kg.Controlgroups receivedmorphine(3mg/kg,s.c.)anddistilledwater(10ml/kg,p.o.) respectively.Acutoffperiodof10swasobserved,toavoiddamage tothetail.

Open-fieldtest

Toevaluatetheeffectoftheextractonspontaneous locomo-toractivity,miceweresubjectedtoopen-fieldtestasreportedby

De Mattoset al.(2007).Groupsofmice(n=5)receivedvehicle,

diazepamorextract(50,100and150mg/kg,p.o.)1hbeforethe test.Eachanimalwasplacedinthemiddleoftheopenfieldfor a5minsessionduringwhichthefollowingparameterswere reg-istered:crossing(thenumberofsquarescrossedwithallpaws), rearing(risingonhindpaws)andtimeofimmobility.

Antiulcerstudies

Ethanol-inducedgastriculcermodel

TheexperimentwasdoneasdescribedbyAkindeleetal.(2012), withslightmodification.Fastedmaleratsweredistributedintofive groupsconsistingofsevenanimalseach.GroupIservedascontrol andreceiveddistilled water(10ml/kg,p.o.);groupsII,IIIandIV receivedtheextractorallyatdosesof50,100and150mg/kg,body weight,respectively.GroupVreceivedmisoprostol(100␮g/kg,p.o)

whichservedasthestandarddrug.Gastriculcerwasinducedinthe ratsbyadministrationoflmlofabsoluteethanol.Animalswere thensacrificed1hafterbycervicaldislocation.Thestomachswere removed,cut along thegreater curvature,washed withnormal saline(0.9%),andulcerindexscoredusingMagistrettiscoringscale

(Magistrettietal.,1988).Gastrictissuesamplesfromeachgroupof

ethanolinducedmodelwerefixedin10%formalin.Then,the for-malinfixedspecimenswereembeddedinparaffinandsectioned (3–5cm)andfurtherstainedwithhematoxylinandeosindye.The sectionswereevaluatedbylightmicroscopyandphotographed.

Indomethacin-inducedgastriculcermodel

The experiment was performed as described by Singh and

Majumdar(1999).MaleWistarrats(130–150g)fastedfor24hwere

treatedorallywiththeextract(50,100and150mg/kg)or omepra-zole(40mg/kg). Distilledwater wasused in thecontrol group. Onehourlater,theanimalswereadministeredwithindomethacin (40mg/kg,p.o.).After6hofindomethacinadministration,animals weresacrificed,andtheirstomachsremoved,cutalongthegreater curvature,washedwithnormalsalineandulcerindexscored.

Statisticalanalysis

Theresultswerepresentedasthemean±S.E.M.Statistical sig-nificancebetweengroupswascalculatedbyanalysisofvariance (ANOVA),followedbyTukey’sorBonferroni’stest.

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Control

50 ₁₀₀ ₁₅₀

ASA (100 mg/kg) 0

50 100 150

Extract (mg/kg, p.o.)

***

_***

No of writhings

Fig.1.EffectofPycnanthusangolensisonaceticacid-inducedwrithinginmice.Each columnrepresentsthemean±S.E.M.(n=7).Datawereanalyzedusingone-way ANOVAfollowedbyTukey’smultiplecomparisontest***p<0.001,comparedwith control.

Results

Acutetoxicitystudy

AsingleoraladministrationofP.angolensisextract(5000mg/kg) didnotproduceanyvisiblesignsorsymptomsoftoxicity,abnormal behaviorandmortalityafter24handsevendaysofobservation.

Antinociceptivestudies

Writhingtest

Theresultoftheaceticinduced-writhinginmiceispresented inFig.1.Theextractdemonstratedadosedependentreductionin aceticacid-inducedwrithinginmice.Theaveragenoofwrithes forthiseffectwas49.14±2.82, 39.43±3.13,22.43±2.84which correspondsto46.75%,57.28%,75.69%inhibitionfor50,100and 150mg/kg, respectively. The effect was statistically significant

(p<0.001) relative tocontrol. Thestandard drug,acetylsalicylic acid(ASA,100mg/kg)showedareductioninthenowritheswith percentinhibitionof81.89,comparedtocontrol.

Formalintest

The effect of ethanolic extract of P. angolensis on formalin inducedpaininmiceisshowninTable1.Theextractina dose dependentmanner reduced the time spent in licking the hind pawat both phases. In thefirst phase, the extractat the dose of50, 100and 150mg/kg reducedthelickingtime with inhibi-tionpercentof35.06,44.47and 60.55,respectively.Thesecond phase showed a markedreduction in the averagelicking time (82.11±5.30,68.17±5.47and47.28±3.30s)atthedoseof50,100 and150mg/kg,respectively.Theaveragelickingtimeinthesecond phasewasrelativelylowerthanthatofthefirstphase.Thestandard reference,morphine,producedahigherinhibitionthantheextract atbothphases.

Tailimmersion

TheresultofthetailimmersiontestwithethanolicextractofP. angolensisispresentedinTable2.Theeffectoftheextractwasnot dosedependentatalldosestested.However,significant antinoci-ceptiveeffect(p<0.01andp<0.001)wasobservedwiththedoseof 150mg/kg,at60,90,and120min,comparedtocontrol.Thepeak effect(43.38%)wasat90min.Morphineexhibitedamaximumpeak ofanalgesiceffect(94.11%)at60minafteradministration.

Openfieldtest

Micetreatedwiththeextract(50,100and150mg/kg,p.o.)did notproducesignificanteffectonthenumberofsquarecrossings, rearing,numberoffecalbolusesandimmobilitywhencompared tothecontrolgroup(Table3).However,diazepamsignificantly (p<0.05)decreasedthelocomotoractivitycomparedtocontrol.

Antiulceractivity

Ethanol-inducedulcerinrats

Thetreatmentofratswithethanolproducedextensivegastric lesionsin the glandularmucosa of stomachin control animals

(Figs.2and3).Ontheotherhand,thepretreatmentoftheanimals

Table1

EffectofPycnanthusangolensisonformalininducedhindpawlickinginmice.

Treatment Dose(mg/kg) 5min 15–30min

Extract 50 85.94±5.31(35.06%)*** _82.11

±5.30(37.43%)***

100 73.12±3.26(44.74%)*** _68.17_±_5.47_(48.05%)***

150 52.19±2.71(60.55%)*** _47.28_±_3.30_(63.97%)***

Morphine 3 0.00±0.00(100%)*** _0.14_±_0.05_(99.92%)***

Control 10ml/kg 132.33±12.91 131.22±14.74

Allvaluesgiveninmean±S.E.M.(n=7).Datawereanalyzedusingtwo-wayANOVAfollowedbyBonferroni’stest.

***_p_<_0.001,_when_compared_with_control.

Table2

EffectofPycnanthusangolensisonnociceptiveresponsesintailimmersiontestinmice.

Treatment Dose(mg/kg) Latencyperiod(min)

0 60 90 120 150

Extract 50 3.36±0.34 7.51±1.96(24.95%) 7.37±1.53(24.07%) 6.15±1.22(16.74%) 4.44±0.71(6.91%) 100 3.84±0.41 5.84±0.66(12.39%) 6.12±0.39(14.12%) 5.08±0.38(7.71%) 3.62±0.5(−1.31%) 150 3.03±0.44 8.43±1.99(31.84%)** _10.39_±_2.00_(43.38%)*** _7.73_±_1.30_(27.69%)** _5.78_±_1.08_(6.24%)

Morphine 3 3.64±0.47 19.04±0.51(94.11%)*** _17.50_±_1.04_(84.74%)*** _16.74_±_1.14_(80.07%)*** _14.01_±_1.35_(63.36%)***

Control 10ml/kg 2.66±0.52 2.86±0.46 2.57±0.38 2.46±0.36 2.10±0.28

Allvaluesgiveninmean±S.E.M.(n=7).Datawereanalyzedusingatwo-wayANOVAfollowedbyBonferoni’stest.

** _p_<_0.01.

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Table3

EffectofPycnanthusangolensisonmiceinopenfieldtest.

Treatment Dose(mg/kg) Numberofsquarecrossing Numberofcentersquarecrossing Numberofrearing Immobility(s)

Control – 66.40±8.80 1.80±0.58 19.80±2.82 76.60±14.42

Extract 50 62.20±5.14 2.20±0.49 18.00±1.67 35.20±9.46

100 64.20±2.06 1.80±0.49 16.40±3.39 40.00±8.96

150 58.20±5.45 2.40±0.51 13.80±1.56 103.20±11.59

Diazepam 1 33.60±9.14* _0.80

±0.37 1.00±0.45*** _198.60

±9.45***

Dataaremean±S.E.M.(n=5).Datawereanalyzedusingone-wayANOVAfollowedbyTukey’smultiplecomparisontest.

***_p_<_0.001.

*_p_<_0.05_compared_with_control.

Control

50 100 ₁₅₀

Misoprostol (100 µg/kg)

0 5 10 15

***

Ulcer score

Fig.2. EffectofPycnanthusangolensisinethanolinducedulcerinrats.Each col-umnrepresentsthemean±S.E.M.(n=7).Datawereanalyzedusingone-wayANOVA followedbyTukey’smultiplecomparisontest***p<0.001,comparedwithcontrol.

with P. angolensis extract (50, 100 and 150mg/kg) exhibited significant(p<0.001)reductionofgastriclesionwithpercentage protectionof47.58%,67.74%and79.26%,respectively.

Theeffect oftheextract at150mg/kg dosewascomparable tothegrouptreatedwithmisoprostol.Histologicalobservationof stomachsectionsofthecontrolgroupshowedcongestednecrotic mucosalsurfaceandinfiltrationofacuteinflammatorycellsintothe

mucosal(Fig.3).However,stomachtissuesofratspretreatedwith thedoseof50,100,and150mg/kgofP.angolensisextract demon-stratedmildlesionsofthemucosaandmildeffectsofhemorrhage, inadosedependentmanner.

Indomethacininducedulcerinrats

The antiulcereffect of ethanolicextract of P.angolensis was alsoassessed in indomethacininducedulcermodel in ratsand theresultispresentedinFig.4.Theextractproducedasignificant dose-dependentreductioninthegastriclesionwithulcerindexof 2.70±0.10,2.60±0.21and2.40±0.56for50,100and150mg/kg, respectively.Omeprazoleusedasreference,producedapercentage protectionof71.93%.

Discussion

Thepresentstudywasundertakentoevaluatethe antinocicep-tiveandantiulcer activitiesofP.angolensis.Theantinociceptive effectoftheextractwasevaluatedonthreeclassicalnociception modelsinmice:aceticacid-inducedwrithingtest,formalintest andtailimmersiontest,whichareusefulmethodsforscreening prospectiveantinociceptivecompoundsorplantextracts.

Intheacutetoxicitystudy,theethanolicextractofP.angolensis, atthedoseof5g/kgexhibitednosignsoftoxicity,indicatingthat theextractmighthaveareasonablylowtoxicityprofile,andcould beregardedasrelativelysafeatthetesteddose(Gregoryetal., 2009).However,furthertoxicity studies;sub-acute and chronic toxicitytestsarenecessaryinordertodeterminethelong-term effectsoftheextract.

The acetic acid-induced abdominal constriction is a visceral painmodel employedasa screeningtoolfor theassessmentof

Fig.3. Histologicalexamination(20×magnifications)oftheethanol-inducedgastricmucosaldamageinrats.(AandA(i))controlgroup;(BandB(i))50mg/kg;(CandC(i)) 100mg/kg;(DandD(i))150mg/kg;(EandE(i))misoprostol(100␮g/kg).Blackarrow:congested,necroticmucosalsurface.Bluearrow:mildmucosaldamage.Redarrow:

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Control

50 ₁₀₀ ₁₅₀

Omeprazole (40 mg/kg). 0

2 4 6 8

*

**

***

Ulcer score

Fig.4. EffectofPycnanthusangolensisonindomethacininducedulcer.Each col-umnrepresentsthemean±S.E.M.(n=5).Datawereanalyzedusingone-wayANOVA followedbyTukey’sMultipleComparisonTest,p<0.05,comparedwithcontrol.

antinociceptive or anti-inflammatory activity of new analgesic agent(DeSouzaetal.,2009).Aceticacidcausesalgesicresponse whichinvolvestheinterperitonealliberationofseveralmediators suchasneurotransmittersandneuromodulators,kinnis,histamine, acetylcholine,substance P and prostaglandins.These mediators increasevascularpermeability,reducethethresholdofthe noci-ceptionandstimulatethenervousterminalofnociceptivefibers

(Gorzalczanyetal.,2011;Pinheiroetal.,2012).Inthismodel,the

extractexhibiteda significantand dosedependentreduction in theaveragenumberofwrithesinmice,comparedtocontrol.This impliesthattheextracthadperipheralanalgesiceffectwhichmay beassociatedwiththereductionoftheliberationofthese inflam-matorymediatorsintotheperitonealcavityorbydirectblockage ofitsreceptorsresultinginanantinociceptiveeffect(Loganayaki etal.,2012).

Thesubcutaneousinjectionofformalininthemiceinducesa biphasicnociceptiveresponse(Ramirezetal.,2010).Thefirstphase whichcorrespondstotheneurogenicpainiscausedbythedirect effectofformalinonthesensoryC-fibers,andfollowedbythe sec-ondphaseortheinflammatoryphasethatisassociatedwiththe developmentofaninflammatoryresponseandthereleaseof noci-ceptivemediatorssuchasprostaglandins,serotoninandbradykinin intheperipheraltissuesandfromfunctionalchangesinthespinal dorsalhorn(Reynosoetal.,2013).Theextractsignificantly inhib-ited both phases of the formalin-induced pain, indicating that theextracthasantinociceptiveeffectinbothphases,significantly attenuatingthepainresponse.

Thetailimmersionmodelisusedtodetermineacutepainand itisausefultesttodifferentiatecentralopioidlikeanalgesicsfrom peripheralanalgesics (Le Barset al.,2001).The antinociceptive effectoftheextractinthismodelwasverylow.Moreover, com-parisonoftheeffectoftheextractwiththatofmorphineshowed thattheextractwasaweakeropioidreceptoragonist.

Theopenfieldtestwasusedtoexcludethepossibilitythatthe anti-nociceptiveactionofextractcouldberelatedtononspecific disturbancesinthelocomotoractivityoftheanimals(Gonc¸alves etal.,2013).Theextractatalldosestestedcausednosignificant changeinthelocomotorcoordinationactivityoftheanimals.The resultstherefore, eliminate thepossibilityoflocomotor impair-mentintheantinociceptiveactivityoftheextract.

Gastric mucosa damage as a result of treatment with non-steroidalanti-inflammatorydrugsisrecognizedasmostserious

adversereactiontothisclassofcompoundsandhasbeenthe stim-ulusbehindmuchoftheresearchaimedatdevelopingnewand effectivegastroprotectivecompounds.Hence,theantiulcer activ-ityofethanolicextractofP.angolensisonthemucosaloftheratwas evaluatedusingethanolandindomethacininducedmodels.

Ethanolinducedulcersareduetodirectnecrotizingeffectof ethanolongastricmucosa(Dharmanietal.,2004).Studiessuggest thattheethanoldamagetothegastrointestinalmucosastartswith microvascularinjury,namelydisruptionofthevascular endothe-liumresultinginincreasedvascularpermeability,edemaformation andepitheliallifting(Szaboetal.,1995).Henceacytoprotective agent,which increasesmucussecretion,willbeeffectiveinthis model.Cytoprotectionhasbeenconsideredtobeduetothe capac-ityofsomecompounds/drugstoinduceprostaglandinproduction, whichinturnsimulatesmucusandbicarbonatesynthesis(Robert

etal.,1983andDeshpandeetal.,2003).Inthisstudy,theextract

atthedoseof50,100and150mg/kgexhibitedadose-dependent gastro-protectiveactivity.Theeffectatthedoseof150mg/kgwas comparable tothatof misoprostol.The abilityof theextractto reducetheethanolinducedgastriculcermaybeanindicationof itscytoprotectiveactivity.

TofurtherconfirmthecytoprotectiveeffectofP.angolensis,the extractwasevaluatedagainstindomethacininducedulcermodel. Indomethacin,anon-steroidalanti-inflammatorydrug,isknown to cause ulcer by inhibiting prostaglandin synthetase through cyclooxygenasepathway(Oyagietal.,2010).Prostaglandins func-tions to protect the stomach from injury by stimulating the secretionofbicarbonateandmucus,maintainingmucosalblood flow andregulatingmucosalturnover andrepair (Hiruma-Lima et al., 2006). The extract significantly reduced gastric mucosal damagecomparedtocontrol.Theabilityoftheextracttoreduce indomethacininducedgastriculcerfurthersupports cytoprotec-tiveeffectandsuggeststhepossiblemobilizationandinvolvement ofprostaglandinsintheantiulcereffectoftheextract.

Inconclusion,theresultsobtainedinthis studyshowedthat

P.angolensis bark extract possesses antinociceptive and antiul-ceractivities,therebyprovidingpharmacologicalreferenceforthe traditionalusesoftheplantinNigeriafolkmedicine.The mecha-nisminvolvedwasnotelucidatedinthepresentstudyandneed furtherinvestigations.Moreover,activityguidedisolationofthe compoundsresponsiblefortheseactivitiesneedtobecarriedout.

Authors’contributions

AOA contributed in collecting plant sample and identifica-tion,runningthelaboratoryworkandanalysisofthedata.MOS designedthestudy,supervisedthelaboratoryworkandwrotethe manuscript.Alltheauthorshave read thefinal manuscript and approvedsubmission.

Conflictsofinterest

Theauthorsdeclarenoconflictsofinterest.

Acknowledgments

TheauthorsacknowledgethetechnicalassistanceofMuyiwaS. FageyinboandSeunNoreen.

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