The Anti-Inflammatory and Antibacterial Action of Nanocrystalline Silver and Manuka Honey on the ...

19 Pages·2015·0.66 MB·English

Hindawi Publishing Corporation
Evidence-Based Complementary and Alternative Medicine
Volume 2015, Article ID 218283, 19 pages
http://dx.doi.org/10.1155/2015/218283
Review Article
The Anti-Inflammatory and Antibacterial
Action of Nanocrystalline Silver and Manuka Honey
on the Molecular Alternation of Diabetic Foot Ulcer:
A Comprehensive Literature Review
Ka-KitTsang,1,2EnidWai-YungKwong,2KevinY.Woo,3 TonyShing-ShunTo,4
JoanneWai-YeeChung,5andThomasKwok-ShingWong6
1O&TDepartment,QueenElizabethHospital,HongKong
2DepartmentofNursing,TheHongKongPolytechnicUniversity,HongKong
3SchoolofNursing,FacultyofHealthSciences,Queen’sUniversity,Kingston,ON,Canada
4DepartmentofHealthTechnology&Informatics,TheHongKongPolytechnicUniversity,HongKong
5TheFacultyofLiberalArtsandSocialSciences,TheHongKongInstituteofEducation,HongKong
6GingerKnowledgeTransferandConsultancyLimited,HongKong
CorrespondenceshouldbeaddressedtoKa-KitTsang;[email protected]
Received26April2015;Revised10July2015;Accepted14July2015
AcademicEditor:EliaRanzato
Copyright©2015Ka-KitTsangetal.ThisisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense,
whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.
Honey and silver have been used since ancient times for treating wounds. Their widespread clinical application has attracted
attentioninlightoftheincreasingprevalenceofantibiotic-resistantbacteria.Whiletherehavebeenanumberofstudiesexploring
theanti-inflammatoryandantibacterialeffectsofmanukahoneyandnanocrystallinesilver,theiradvantagesandlimitationswith
regardtothetreatmentofchronicwoundsremainasubjectofdebate.Theaimofthispaperistoexaminetheevidenceonthe
useofnanocrystallinesilverandmanukahoneyfortreatingdiabeticfootulcersthroughacriticalandcomprehensivereviewofin
vitrostudies,animalstudies,andinvivostudies.Thefindingsfromtheinvitroandanimalstudiessuggestthatbothagentshave
effectiveantibacterialactions.Theiranti-inflammatoryactionandrelatedimpactonwoundhealingareunclear.Besides,thereis
noevidencetosuggestthatanytopicalagentismoreeffectiveforuseintreatingdiabeticfootulcer.Overall,high-quality,clinical
humanstudiessupportedbyfindingsfromthemolecularscienceontheuseofmanukahoneyornanocrystallinesilverarelacking.
Thereisaneedforrigorouslydesignedhumanclinicalstudiesonthesubjecttofillthisknowledgegapandguideclinicalpractice.
1.Introduction in the topical treatment of wounds, as evidenced from the
textoftheSmithpapyrus[5].Adocumentfrom1392details
Theuseofsilverasaprophylacticandtreatmentforinfections wound care practices, including the use of honey, in the
andotherdiseasesdatesbacktoabout100BC,whenitwas Middle Ages [6]. However, the use of honey came to be
used for this purpose by the ancient Greeks and Romans consideredoutmodedaroundthe1940s,followingtheadvent
[1].Inthelatenineteenthcentury,therewasaresurgenceof of antibiotics. With the recent increase in multiresistant
interestinusingsilvercompoundstotreatvenerealdiseases bacteria due to the overuse of antibiotics in the past few
andeyeinfections[2].Thetopicalapplicationofhoneywas decades,thepotentialofhoneyandsilverinthemanagement
also a common practice for centuries [3] by the Egyptians, of various chronic wounds such as diabetic foot ulcers,
Greeks, Romans, and Chinese [4]. The early Egyptians of venousulcers, and pressure ulcers has spurred new interest
around1650BCwerethefirsttousehoneyasacomponent inthewoundcarecommunity[7].
2 Evidence-BasedComplementaryandAlternativeMedicine
2.TheChallengeofManaging impairedalongthemarginofchroniculcersinpatientswith
DiabeticFootUlcers diabetes mellitus. Albiero et al. [34] discovered that wound
healing delayed as a result of diabetes was associated with
Diabeticfootulcer(DFU)isthefocusofthepresentreview thedefectiverecruitment,survival,andproliferationofBM-
becauseofthehighprevalenceofthediseaseandtheburden derived endothelial progenitor cells in mice. Macrophages
it places on the health system. It is estimated that diabetes isolated from diabetic mice also exhibit greater infiltration
affects8.3%oftheglobalpopulationor382millionpeople[8]. by inflammatory M1 macrophages and may contribute to
Thisnumbercontinuestogrow,makingDFUamajorpublic impaireddiabeticwoundhealing[35].
health problem [9]. Foot ulcer is a common complication,
affecting 4%–10% persons with diabetes mellitus [10] and 2.2. Poor ECM Formation and High Levels of MMPs. The
preceding over 85% of amputations in this population of ECMformationisdefectiveinDFU.ECMcreatesascaffold
patients[11].Theriskofcomplicationincreaseswithtime.The forcellularattachment,whichiscrucialforwoundhealing.
cumulative incidence of DFU increases from 27.3% during Blakytny and Jude [29] stated that the disruption in the
thefirstyearofdiagnosisto76.4%fiveyearsaftertheinitial formationofnewECMaswellasthediminishedstimulation
diagnosis. The rate of amputation increases from 12.5% to ofcellproliferationresultsinthelackofaproperscaffoldfor
47.1%[12]. cellularattachment.
Thecostofcaringforpeoplewithdiabetesisexorbitantly MMPs are zinc-dependent endopeptidases, and their
high, amounting to $174 billion in the United States in inhibitors are called tissue inhibitors of matrix metallopro-
2007, of which foot ulceration accounted for 24% to 31% teinases(TIMPs).Theyareexcretedbyavarietyofconnected
[13]. Stockl et al. [14] revealed that the average cost per tissue,fibroblasts,keratinocytes,proinflammatorycellssuch
DFU episode was $13,179, and greater in the case of deep as neutrophil, and macrophage. Those MMPs are regulated
ulcerswithcoexistinginfectionandcirculationproblems(as by hormones, growth factors, and cytokines in response to
evaluatedusingtheWagnerclassificationsystem).Apartfrom signals[36,37].ThefunctionsofMMPsincludeinfluencing
the financial impact of DFU, patients with DFU experience cell migration, promoting cellular proliferation apoptosis,
many limitations in their physical, social, and vocational modulatinggrowthfactorsandtheirreceptors,anddegrad-
activities(especiallythosewhowererequiredtoundergoan ingthestructuralcomponentsofECMduringtheremodeling
amputation), leading to poor health-related quality of life oftissue[37,38].
(HRQOL)[15,16]. In diabetic patients, hyperglycaemia activates the path-
There are multiple factors behind the development of waysofthemitogen-activatedproteinkinasetostimulatethe
DFU, with neuropathy, peripheral vascular disease (PVD), productionofcytokineandpromoteinflammation[39].The
and foot deformity being the most prominent risk factors high level of MMPs is also the pathological alternation in
[17,18].Thelackofprotectivesensationpredisposesaperson DFUinbiochemicalterms.TheoverexpressionofMMPsand
withdiabetestosufferingfromrepetitivetraumaandulcers elastase breaks down the components of ECM and inhibits
thatdonothealduetopoorcirculation[19].Woundhealing growthfactors[40].Lobmannetal.[41]comparedtheMMP
can be further complicated by bacterial infections [20, 21] levels of 20 patients with diabetic foot ulcers with those of
and prolonged inflammation [22–25]. The reasons for such 12patientswithtraumaticulcers.Theresultsshowedthatthe
prolonged and excessive inflammation are still unclear [22, concentrationsofMMP-1andMMP-9increased65-foldand
26], but they likely involve bacterial colonization, biofilms, 14-fold,respectively,inthediabeticulcerbiopsies.Mulleret
and recurrent tissue trauma [27]. Apart from the obvious al. [42]conductedanothercohortstudyonsixteen patients
clinicalpredisposingriskfactors,recentstudieshaverevealed withneuropathicdiabeticulcers.Theresultsechoedthoseof
that complex cellular and molecular aberrations such as Lobmann’sstudy.ThelevelsofMMP-8andMMP-9decreased
poor extracellular matrix (ECM) formation, high levels of in the good healer group and remained stable in the poor
matrixmetalloproteinases(MMPs),andotherproinflamma- healergroupduringthe12-weekfollow-upperiod.
torycytokines,aswellasoxidativestress,areresponsiblefor
delayedhealing[28]. 2.3.HighProinflammatoryCytokines. Tohealulcers,proin-
flammatory cytokines can chemotactically draw inflamma-
2.1. Cellular Abnormalities. The exact mechanisms behind tory cells into the injured area [43]. Lobmann et al. [27]
poor wound healing remain elusive [29]. Loots et al. [30] statedthattheupregulationofTNF-𝛼andIL-1stimulatesthe
showedadiminishedproliferativecapacityandanabnormal synthesis of MMP-1 and inhibits the synthesis of collagen.
morphology of fibroblasts in wounds related to diabetes. Trengove et al. [44] found in an in vitro study the upregu-
Galkowska et al. [31] found in an in vitro study that the lationofinterleukin-1(IL-1),interleukin-6(IL-6),andtumor
healing process of diabetic foot ulcers may be hampered necrosisfactor-alpha(TNF-𝛼)inchronicnonhealingulcers.
bymechanismsthatreducetheaccumulationofleukocytes. On the otherhand, decreased levels of all proinflammatory
Waltenbergeretal.[32]performedachemotaxisassayusing cytokinescanimprovewoundhealing.Chanetal.[45]found
isolated monocytes from diabetic patients and found that inaninvitrostudythattheneutralizationofTNFindiabetic
monocytes are less responsible for the vascular endothelial woundsimprovestheangiogenesis.
growthfactor(VEGF)whencomparedwithnormalperson.
Usingimmunohistochemistrytechniques,Usuietal.[33]dis- 2.4. High Oxidative Stress. People with diabetes usually
coveredthatkeratinocytemigrationanddifferentiationwere havehyperglycemia.Thereisincreasingevidencetosuggest
Evidence-BasedComplementaryandAlternativeMedicine 3
a causal link between hyperglycemia and oxidative stress [57]. This will lead to the formation of hydroxyl radicals
leading to cellular damage [40]. Excessively high levels of andtoanattackonthecellitselfandsubsequentlytoDNA
free radicals cause damage to cellular proteins, membrane damage[58].Besides,silverionsinducedapoptoticpathways
lipids, and cell nucleic acids and eventually lead to cell inside the bacteria, leading to their death [54, 56]. Pandian
death[46].Inpeoplewithdiabetes,freeradicals(superoxide etal.[59]conductedaninvitrostudytoechotheapoptotic
anionandhydroxylradial)areformedindisproportionately pathways.Theyfoundthatbacteriathatshowedevidenceof
highlevelsbyglucoseoxidation,thenonenzymaticglycation apoptosisanddeoxyribonucleicacid(DNA)werefragmented
of proteins, and the subsequent oxidative degradation of afterexposuretonAg.
+
glycated proteins. The glycated proteins develop further InvitroevidenceshowsthatnAg hasauniqueantibacte-
reactions to form advanced glycation end products (AGEs) rialactiononcells.Thereisanelectrostaticattractionbetween
+
[47,48].TheaccumulationofAGEscausestheupregulation nAg and the negative charge cell membranes of bacteria.
of proinflammatory cytokines and MMPs that will degrade nAgbindstothemodifiedphospholipidbilayerandinduces
+
ECM through the production of reactive oxygen species amassiveleakageofprotons[60].WhennAg anchorstothe
(ROS) [29]. The production of peroxynitrite anion and bacterial cell wall and causes structural change by forming
peroxynitrous acid [49] can also lead to biological damage irregular-shaped“pits”onthebacterialoutermembrane,the
[50].ThemolecularalternationsofDFUaresummarizedin permeabilityofthemembranechangesandbecomesporous
Table1. [61].Inanelectronspinresonancespectroscopystudy,Kim
Because of the molecular alternations of DFU et al. [62] further discovered that that nAg generates free
showninTable1, DFU is difficult to treat clinically. Many radicals,whichcandamagethebacterialcellmembrane.The
cliniciansattempttoapplydifferenttopicaldressingmaterials cell will then progressively release lipopolysaccharides and
to treat DFU. However, few high-quality studies have been membraneprotein,whichwillultimatelycausethecelltodie.
conducted to guide clinical practice on the application of Mirzajanietal.[63]furtherinvestigatedtheeffectofnAgon
topical dressing materials. In the recent Cochrane database Gram-positive Staphylococcus aureus. They discovered that
on systematic reviews, no papers related to honey and nAg exerted on the bacterial peptidoglycan cell wall and
silver met the inclusion criteria in this review because of specificallydecomposeditspeptidepart.Byattachingtothe
the poor quality of the papers [51, 52]. Even though many bonds of glycan strands composed of N-acetylglucosamine
randomizedcontrolledtrialshaverecentlybeen conducted, and N-acetylmuramic acid, nAg destroyed the bonds and
they suffer from methodological flaws related to the design released muramic acid. As a consequence, “pits” were gen-
of the research, including a small sample size, deficient erated on the bacterial cell membrane. However, the exact
randomization or blinding, and poor statistical analysis. mechanismthatoccurredontheGram-negativemembrane
Moreover, it is difficult to pool together and analyze trials remainedunknown.McQuillianetal.[64]continuedwork-
ondressingmaterialsbecauseofthediversityofthestudies ingonGram-negativebacteriaandinvestigatedtheeffectof
[53]. At the same time, honey and silver are widely used nAg on Escherichia coli. Using inductively coupled plasma
by clinicians to treat DFU because of their antibacterial massspectrometry,theydiscoveredthattheprimarymecha-
effect. In the present review, we examine the evidence nismofnAgwastointeractwithanddissolvetheouterand
+
relating to the anti-inflammatory and antibacterial actions innermembranesofacell;thenAg releasedintothecelland
ofnanocrystallinesilver(nAg)andmanukahoney(MH)to affectedatranscriptionalresponse.
determinetheireffectsonthemolecularalternationofDFU. In addition, nAg can dephosphorylate the peptide sub-
strateontyrosineresidues.Mijakovicetal.[65]demonstrated
3.ActionofNanocrystallineSilver thatthephosphorylationofproteinsubstrateinbacteriacan
influencebacterialsigntransduction.Shrivastavaetal.[66]
3.1.AntibacterialEffectofnAg. nAgcanincreasethesurface found that the inhibition of this mechanism by nAg can
area that is in contact with the wound surface [54]. The influence the signal transduction and stop the growth of
bactericidaleffectofnAgdependsonitssize.Itispreferable bacteria. In summary, the overall effect of nAg is both to
for nAg to be around 1–10nm in size, as this is the size at inhibitthereproductionofbacteriaandtokillthemdirectly.
which direct interaction can occur with the surface of the
cellsandwithinthebacteria[55].Thus,nAgcanincreasethe 3.2. Bacterial Resistance to Silver. However, some reports
bioactivityandsolubilityofsilvertoallowchemicalreactions have documented bacterial resistance to silver on possible
totakeplace[112].Apartfromsize,theshapeofnAgcanalso woundpathogens.ThepathogensincludedProvidenciastuar-
affect their bactericidal effect. Pal et al. [56] found that the tii[114],Enterobactercloacae[115],Pseudomonasspecies[116],
bactericidal action of a truncated triangular shape exceeds Acinetobacter baumannii [117], and E. coli [118]. Laboratory
thatofasphericalaswellasarodshape.Asregardsantibacte- studiesfoundthattheeffluxofsilverionsortheacquisitionof
rialaction,Loketal.[113]revealedtheexposureofEscherichia geneticmaterialintheformofplasmidswasthemechanism
coli(E.coli)tonAgforashorttime.Theydiscoveredthatthe ofasilver-resistantE.colimutant[119].
mechanismsofnAgandsilverionsweresimilarbutthatnAg Some researchers have claimed that the clinical inci-
appearstobesignificantlymoreefficientthansilverions.nAg dence and probability of multiple mutations remain low
+
and Ag share the following common bactericidal effects. even though silver resistance has been documented [120,
Silverionscaninteractwiththiolgroup-containingenzymes, 121]. Unlike antibiotics, silver attacks more than one of the
such as NADH-dehydrogenase II in the respiratory system target specific sites [122] and there is no direct evidence
4 Evidence-BasedComplementaryandAlternativeMedicine
n
en
ble1:ThemolecularalternationsofDFU. CellularabnormalitiesFibroblastsdecreaseproliferativecapacityandabnormalmorphologyLeukocytesdecreaseaccumulationMonocytesindiabeticpatientarelessreactivetoVEGFImpairedmigrationanddifferentiationofkeratinocytesReducedintherecruitment,survival,andproliferationofendothelialprogenitorsatthesiteoftheinjuryDecreasedinthepolarizationandactivationofmacrophagesPoorECMformationAGEscausetheupregulationofMMPsandcytokinesthatdegradesECMthroughtheproductionofROSTheoverexpressionofMMPsandelastasebreaksdownthecomponentsofECMandinhibitsgrowthfactorsHighlevelsofMMPsMMP-1andMMP-9increased65-foldand14-fold,respectively,indiabeticulcerbiopsiesMMP-8andMMP-9remainedstableinthepoorhealergroupbutdecreasedinthegoodhealergroupHighproinflammatorycytokines𝛼TheupregulationofTNF-andIL-1stimulatedthesynthesisofMMP-1andinhibitedthesynthesisofcollagHyperglycaemiaactivatesthepathwaysofmitogen-activatedproteinkinasetostimulatecytokineproductioandpromoteinflammation𝛼IL-1,IL-6,andTNF-areupregulatedinchronicnonhealingulcersNeutralizationofTNFimprovestheangiogenesisHighoxidativestressFreeradicals(superoxideanionandhydroxylradicals)areformedbytheoxidativedegradationofglycatedproteins,whichsubsequentlyformAGEsTheproductionofperoxynitriteanionandperoxynitrousacidcanleadtobiologicaldamage
a
T
y y y y y
d yyd d d d
u ddu u u u
ofstvitrovivovitrovivoalstualstuofstviewviewofstvivovivoofstview view vivovitroofst vitro view
NatureInInInInAnimAnimNatureReReNatureInInNatureRe Re InInNature In Re
AuthorLootsetal.,1999Galkowskaetal.,2005Waltenbergeretal.,2000Usuietal.,2008Albieroetal.,2011Kanteretal.,2012AuthorBlakytnyandJude,2006SibbaldandWoo,2008AuthorLobmannetal.,2002Mulleretal.,2008AuthorLobmannetal.,2005 McLennanetal.,2008 Trengoveetal.,2000Chanetal.,2012Author vandenBergetal.,2008 Sonejaetal.,2005
r r r r r
e e e e e
b b b b b
m m m m m
Nu30]31]32]33]34]35]Nu29]40]Nu41]42]Nu27] 39] 44]45]Nu 47] 49]
[[[[[[ [[ [[ [ [ [[ [ [
Evidence-BasedComplementaryandAlternativeMedicine 5
that silver resistance mechanisms confer cross-resistance to dressingforahistopathologicalanalysisinvolvingmice.The
antibiotics[120].Percivaletal.[123]continuedtheworkon result demonstrated that nAg dressings have a significant
Ag-containingwounddressingsinvitro.Theyconcludedthat inflammatory effect on a noninfected inflammatory skin
despiteevidenceofgeneticresistancetosilver,allstrainswere model, equivalent to that obtained using topical steroid
killedfollowingamaximumof48hoursofexposuretothe cream.
dressings. In addition, there is some in vivo evidence showing
that nAg has an anti-inflammatory effect. Shin et al. [74]
3.3. Anti-Inflammatory Effect of nAg. Compared with the performed the work in human cells. The result showed
antibacterialactionofsilver,theexactmechanismofitsanti- that TNF-𝛼 and interferon-𝛾 were significantly inhibited at
inflammatory action is still unclear. To our knowledge, the low concentrations of nAg of over 3ppm. Mani et al. [75]
studiesthathavebeenpublishedonthesubjecthavefocused examinedtheeffectofsyntheticnAgonhealthyhumancells.
on the observable effect of the anti-inflammatory action of Theyalsoshowedthatallthreecytokines(TNF-𝛼,IL-1𝛽,and
silver,insteadofonthedetailedmolecularmechanism.The IL-6) were inhibited at concentrations ranging from 10 to
animalandinvivoevidenceshowingtheanti-inflammatory 20𝜇g/mL.Obviously,fromthepublishedanimalandhuman
effect of nAg are as follows. Wright et al. [67] discovered studies,theanti-inflammatoryeffectofnAgisclearalthough
thatafull-thicknesscontaminatedwoundinaporcinemodel the exact pathway is still unknown. Interestingly, all histo-
treatedwithnAghealedmorequicklyandwasaccompanied logicalfindingsdemonstratedapoptosisoftheinflammatory
with a decrease in MMP activities as well as with the stim- cellsinducedbynAg,sothatavoidingtheinflammatorycells
ulatedapoptosisofpolymorphonuclearleukocytes(PMNs). produces chemoattractants to induce further inflammation
Theysuggestedthatenhancedcellularprogrammedcelldeath upon bursting. In addition, all of the molecular findings
(apoptosis) would decrease the number of cells to release indicated that the TNF-𝛼 expression was downregulated.
cellularcontentwithnumerouscytotoxiccompoundssuchas In diabetic wound healing, impairing the proliferation of
proteases,oxygenradicals,andvariousacids,inturndecreas- fibroblasts has been linked to an increase in the level of
inglocalinflammation.Bholetal.[68]hadsimilarfindings. TNF-𝛼 [124]. When the level of TNF-𝛼 level was inhibited,
Through clinical observations, they found that topical nAg therewasincreaseinthenumberoffibroblastsproliferation
creamwaseffectiveatdecreasingallergiccontactdermatitis significantly [125]. Therefore, we can hypothesize that the
on a guinea pig model and that the effect was similar to anti-inflammatory effect of nAg may be beneficial to the
thatachievedusingtopicalsteroidsandimmunosuppressive healing of DFU. The actions of nAg are summarized in
drugs.BholandSchechter[69]furtherextendedtheirwork Table2.
using a rat model. From a histological and immunohisto-
chemical examination, they discovered that nAg had the 3.4.ClinicalEvidenceontheUseofnAg-ImpregnatedDressings
ability to inhibit contact dermatitis by suppressing TNF-𝛼 onDFU. Todate,nounifyingtheorieshavebeenestablished
andIL-12,aswellasinducingtheapoptosisofinflammatory throughtheabovebasicscienceresearchandbroughtintothe
cells. Similar to previous findings, Wong et al. [70] showed clinical context. Nevertheless, researchers have investigated
that nAg was effective at decreasing inflammation through Ag or nAg topical dressings and tried to link their findings
the downregulation of the production of TNF-𝛼, without a with the observable clinical outcome. Unfortunately, there
significant toxic effect on a peritoneal adhesion model of havebeenfewclinicalstudiesontheeffectofnAgonDFU.
mice. We searched different databases for studies on the effect of
Nadworny et al. continued the work that had been Ag or nAg dressings on DFU that had been published in
conducted on the effect of nAg by using different animal the past 10 years and identified one case report [126], two
models. The results echoed the previous findings. They caseseriesstudies[127,128],tworandomizedcontrolledtrials
further discovered that nAg had the ability to promote (RCT)[129,130],andonemeta-analysis[52].Sincetheeffect
healingbecausesomekindsofgrowthfactorswereelevated ofnAgismorepotentthanAgandthemolecularmechanism
after the topical nAg intervention. Using a porcine model, isnotexactlythesame,thenon-nAgstudieswereexcluded
Nadworny et al. [71] found that treatment with solutions fromtheanalysis.Onlyonecaseseriesstudyinvestigatedthe
containing nAg resulted in a decrease in proinflammatory effectofnAg.CahnandKleinman[127]usedanonsurgical
cytokinesTNF-𝛼andIL-8expression,withanincreaseinIL- approach to treat six patients with diabetic foot abscesses.
4,epidermalgrowthfactor(EGF),keratinocytegrowthfactor Theabscessesweretreatedwithtopicaloxygenanddrained
(KGF),andKGF-2expression.Againusingaporcinemodel, usingnAgfoamrope(PolymenWicSilverRope).Theeffect
Nadwornyandcolleagues[72]alsodiscoveredthatnAgwas on debridement and oxygen therapy on the diabetic foot
mainly deposited in the epidermis but that cell apoptosis abscesses could not be excluded. In this case series study,
waslargeinthedermisandminimalintheepidermis.They thepatientsvariedintermsoftheirhistoryofdiabetes(5to
thereforeproposedthattheanti-inflammatoryeffectsofnAg 20 years) and ankle brachial index score (0.57 to 1.63). The
were induced by interactions with cells in the top layers durationoftheirtreatmentrangedfromtwotoeightmonths.
of the skin, which then released biological signals resulting Inaddition,threepatientssufferedfromperipheralvascular
in widespread anti-inflammatory activity. nAg induced the disease. During the period that they were being treated for
downregulationofTNF-𝛼andIL-8expression,aswellasthe diabetic foot abscesses, they also underwent percutaneous
upregulation of IL-4, IL-10, EGF, KGF, and KGF-2. Bisson revascularization.Althoughallofthepatientswithdiabetic
et al. [73] furthered the work on the latest nAg topical footabscessandosteomyelitishadcompletelyhealedwithin
6 Evidence-BasedComplementaryandAlternativeMedicine
e n
Table2:ModesofactionofnAg. MechanismofantibacterialactionIncreasesthesurfaceareacontactingthewoundsurfaceHaveadirectinteractiononthecellsurfaceandwithinthebacteriawithadiameterofaround1–10nmThebactericidalactionofnAgwithatruncatedtriangularshapeexceedsthatofnAgwithasphericalorrodshapInteractswiththethiolgroupofrespiratoryenzymesInactivatesthekeyenzymebyblindingthethiolgroup,formingfreeradicals,andsubsequentlydamagingDNAInteractswithandcondensesphosphorus-containingDNAandcytoplasm(apoptosis)andinhibitscellreplicatioBindstothemodifiedphospholipidbilayerandinducesamassiveleakageofprotonsAttachesthenegativelychargedcellmembranebyforming“pits,”makingthemembraneporousandresultinginleakageofintracellularcontentBacteriareleasecellularcontentafterthepermeabilityofthecellmembraneincreases,leadingtocelldeathDestroyedthebondsofglycanstrandscomposedofN-acetylglucosamineandN-acetylmuramicacidinthecellmembraneofGram+vebacteriaandcausing“pits”toform−+InteractswiththeouterandinnermembraneofGramvebacteria,andthenmembranedissolves;AgreleasesintothecellandaffectsatranscriptionalresponsePhosphorylationoftheproteinsubstrateinbacteriacaninfluencebacterialsigntransductionandcellcycleprogressionMechanismofanti-inflammatoryactionReducestheactivityofMMPsandstimulatestheapoptosisofPMNs,leadingtoadecreaseinthereleaseofcytotoxiccompoundssuchasproteasesandoxygenradicalsEffectivelydecreasesallergiccontactdermatitisonaguineapigmodel,similartotopicalsteroids𝛼SuppressestheactivitiesofTNF-andIL-12andinducestheapoptosisofinflammatorycells𝛼DownregulatestheproductionofTNF-withouthavingasignificanttoxiceffectonaperitonealadhesionmodel𝛼DecreasesTNF-andIL-8andincreasesIL-4,EGF,KGF,andKGF-2𝛼DownregulatesTNF-andIL-8andupregulatesIL-4,IL-10,EGF,KGF,andKGF-2Demonstratesasignificantinflammatoryeffect,equivalenttothatwhichresultsfromusingtopicalsteroidcream𝛼𝛾TNF-andinterferon-aresignificantlyinhibitedatlowconcentrationsofnAg𝛼𝛽𝜇TNF-,IL-1,andIL-6areinhibitedatconcentrationsrangingfrom10to20g/mL
y y
d y d y yyyyyy
u d u d dddddd
ofstviewvitrovitrovitroalstuvitrovitro vitro vitro vitro vitro vitro ofst alstu alstualstualstualstualstualstuvivovivo
NatureReInInInAnimInIn In In In In In Nature Anim AnimAnimAnimAnimAnimAnimInIn
4
0
AuthorKonandRai,2013Moronesetal.,2005Paletal.,2007Matsumuraetal.,2003Gordonetal.,2010Pandianetal.,2010Dibrovetal.,2002 ndiandSalopek-Sondi,20 Kimetal.,2007 Mirzajanietal.,2011 McQuillanetal.,2012 Mijakovicetal.,2006Shrivastavaetal.,2007Author Wrightetal.,2002 Bholetal.,2004BholandSchechter,2005Wongetal.,2009Nadwornyetal.,2010Nadwornyetal.,2010Bissonetal.,2013Shinetal.,2007Manietal.,2015
o
S
r r
e e
b b
m m
Nu54]55]56]57]58]59]60] 61] 62] 63] 64] 65]66]Nu 67] 68]69]70]71]72]73]74]75]
[[[[[[[ [ [ [ [ [[ [ [[[[[[[[
Evidence-BasedComplementaryandAlternativeMedicine 7
two to nine months by treatments using debridement, a antibacterial action of MH is mainly based on its physical
topical oxygen extremity chamber, and Polymen Wic Silver properties and on the active ingredient that it contains.
Rope,wecouldnotdeterminethesoleeffectofnAgfoamin First, honey has an osmotic effect, drawing moisture from
thisstudy. the environment and dehydrating bacteria [76]. This effect
is reduced after dilution by wound exudate [141]. Second,
3.5.CytotoxicityEffectofSilveronModernWoundDressings. the pH value of MH is between 3.2 and 4.5. This acidic
The cytotoxicity of silver is an issue that has been debated. nature can inhibit the growth of most microorganisms,
Lansdown[131]claimedthattoxicityfromdressingscontain- such as E. coli, Pseudomonas aeruginosa (P. aeruginosa),
ing silver is rare because in modern dressings the silver is Salmonellaspecies,andStreptococcuspyogenes[77,142,143].
in a controlled-release preparation and some of the silver Third, methylglyoxal (MGO) is one of the phytochemical
ionsbindtotheproteinofthewoundexudate.Ontheother factors with antibacterial activity that have been identified
hand, in vitro and animal studies have shown that silver within MH. In vitro studies have revealed that the MGO
dressings have significant cytotoxic effects on keratinocytes in MH contains the majority of the nonperoxide activity
and fibroblasts [132, 133]. Van den Plas et al. [134] found and that the amount of MGO is closely related to the
that silver dressings induced rapid cell death within two level of antibacterial activity [78, 79]. Ordinary honey has
hours;theyrecommendedtheuseofsilverdressingsonlyon a limited amount of MGO, ranging in concentration from
critically contaminated wounds. Zou et al. [135] compared 1.6 to 135mg/kg, compared to 38–725mg/kg in manuka
differentpairsofAg-basedandnon-Ag-baseddressingswith honey[78].Aminimuminhibitoryconcentration(MIC)for
basicmaterialsinvitro.Theresultshowedthathumanfibrob- E. coli and Staphylococcus aureus (S. aureus) was observed
lasts,whichwereextractedfromdiabeticpatients,decreased at 1.1mM of MGO [79]. Atrott and Henle [80] also found
in viability by 54–70% and collagen synthesis by 48–68% a linear correlation between MGO levels in 61 samples of
when they came into contact with the Ag-based dressings manuka honey and antibacterial activities. There were also
compared with the non-Ag-based dressings. They did not someotherunidentifiedbiochemicalsubstancesintheMH,
suggestdiscardingAgdressingsbutstatedthatsuchdressings whichlaterlaboratorystudiesrevealedtoalsocontributeto
should be used with caution when treating noninfected antimicrobial activity. Kwakman et al. [81] identified some
diabetic wounds. Therefore, the international consensus on cationic and noncationic compounds that contributed to
theuseofsilveristhatsilvershouldbediscontinuedifwound bactericidalactivitiesagainstdifferenttypesofbacteriaafter
infectionisnolongerpresent[136]. theneutralizationofMGO.Katoetal.[82]foundaglycoside
However,thefindingsfromrecenthumanstudiesdonot of methyl syringate called “Leptosin,” which had a positive
support the view that using modern silver dressings could correlationwithantibacterialactivityinMH.
lead to cytotoxicity. Karlsmark et al. [137] noted that the Unfortunately,theexactmechanismcontributingtothe
serumsilverlevelforpatientstreatedwithasilverdressings bactericidal activity of MH remains largely unknown [78].
wasnohigherthanthereferencevalue,althoughfivepatients The antibacterial action of MH was recently explored with
experiencedatemporaryincreaseintheirsilverlevel.Gago thehopeofelucidatingtherelatedmechanism,butitsprecise
etal.[138]providedfurtherevidencethatahighlevelofAg mode of antibacterial action is only just beginning to be
rapidlyreducesinfectionandresultsinthefasterhealingof understood. In vitro studies have demonstrated that cell
infected chronic wounds. Lansdown et al. [139] discovered division is interrupted and cell separation cannot occur
that the ions from a silver dressing penetrate only several followingtheformationofseptaonS.aureus[83]andMRSA
millimeters into the wound bed. The available information [84] when these bacteria are exposed to MH. Roberts et al.
indicatesthatthefindingsfromtheinvitrostudiesareincon- [85] observed extensive cellular lysis of P. aeruginosa at an
sistentandthatknowledgeonthecytotoxicityofAgandnAg MIC concentration of 12% w/v in MH. The honey-treated
dressings is incomplete. Based on our existing knowledge, cellswereunabletoformmicrocoloniesandtwotargetgenes
it can be said that silver has both anti-inflammatory and wereidentifiedasbeinginvolvedintheprocess.Inaddition,
antibacterialproperties.Indeed,toxicityfromthelong-term Packeretal.[86]foundthatMHcausestwodifferentproteins
use of silver in clinical practice cannot be completely ruled tobedownregulatedandonetobeupregulatedonS.aureus.
out, especially when silver is used as an anti-inflammatory Thesetwoproteinshadrolestoplayinribosomalfunction,
moderatorinsteadofanantibacterialagent.Furtherresearch protein synthesis, the metabolic process, and transcription,
is needed in this area to ensure the clinical safety of using indicatingthatMHcouldinterferewiththeribosomeorits
silverdressingtherapyoverthelongterm[140].Thereisboth translational capacity. Merckoll et al. [144] discovered that
aknowledgegapandaclinicalquerywithregardtotheuseof honeyhasbactericidaleffectsonbothplanktonicandbiofilm-
silverasananti-inflammatorymoderatorfortreatingwounds embedded bacteria, since bactericidal substances in honey
withnoinfectionbutwithinflammation. canpenetrateintothebiofilm.Maddocksetal.[87]further
foundthatMHdecreasestheformationofbiofilmbyinhibit-
4.ActionofManukaHoney ing the Streptococcus pyogenes from binding to fibronectin.
It has this effect because this binding is important for the
4.1. Antibacterial Action of Manuka Honey. MH, which colonizationofbacteriaandthedevelopmentofbiofilm[145].
comes from Leptospermum scoparium in New Zealand, Ironisnecessarytosustainthegrowthofbacteria.P.aerug-
exhibits antibacterial activity [76]. Our body of knowledge inosa produced two extensively characterized siderophores
on its antibacterial mechanism remains incomplete. The to capture iron [146]. Kronda et al. [88] further discovered
8 Evidence-BasedComplementaryandAlternativeMedicine
that MH decreased the production of siderophores at both couldimpairthewound-healingprocess.Inaninvitrostudy,
1/4 and 1/2 MIC, showing that MH impeded the growth of Sassi-Gahaetal.[153]foundthathighlyreactivedicarbonyls
the cells. So far, the above in vitro evidence suggests that attacked the lysine, arginine (Arg), and cysteine residues
there is no single mechanism to antimicrobial action but of long-lived proteins (e.g., collagens) to form irreversible
that a combination of factors results in diverse modes of AGEs, causing changes in collagen pathophysiology. There-
antibacterialinhibitionandkilling. fore,thereisclearlyapaucityofhigh-qualityhumanstudies
Compared with antiseptics that decrease the bacterial relatingtotheuseoftopicalhoneytotreatdiabeticulcers.
count within minutes, the antibacterial activity of MH is
muchslower[146].Thelatestlaboratorystudiesexplainthis
phenomenon. Kwakman et al. [81] showed that MH does 4.2.Anti-InflammatoryActionofManukaHoney. Honeyhas
not have a rapid antibacterial effect against different kinds beenshowntoreducebothacuteandchronicinflammation,
ofbacteriainthefirst2hoursbutthatitspotencyincreases although the mechanism for this anti-inflammatory action
after 24 hours. The reason for the slow onset action relates is not entirely understood [154]. The antioxidants found in
to the fact that MH lacks major factors involved in rapid honeyareconsideredtobeimportantdeterminantsofanti-
antibacterial activity, such as bee defensin-1 and hydrogen inflammatory activity [155]. The antioxidant properties of
peroxide. The main active ingredient in the antibacterial honeyarebeneficialincounteractingadvancedglycationand
effect of MH is MGO. Adams et al. [147] found that MGO lipoxidationendproducts,whichcaninduceoxidativestress
forms through the conversion of dihydroxyacetone. This andinflammationindiabetics[156].Naturalhoneycontains
conversionisanonenzymaticreactionthattakesplaceinthe flavonoids, phenolic acids, and other enzymes. All of the
presence of proteins or amino acids. The concentration of active components work together to provide a synergistic
MGO is low in freshly produced honey but increases after anti-inflammatory and antioxidant effect [157]. Chan et al.
∘
storageat37 C. [94] revealed that pinobanksin, pinocembrin, luteolin, and
MHhasananti-antibacterialeffectondifferentmicroor- chrysinwerethemajorflavonoidsfoundinMH,accounting
ganismsinvitro.Therateofinhibitiondependsonthespecies for 61% of the total flavonoids. Low levels of quercetin
ofbacteriaandtheconcentrationofhoney[141,148].Cooper and galangin were also found. Flavonoids are known for
et al. [89] found that MH would still prevent the growth their anti-inflammatory activity. Cho et al. [96] found that
of S. aureus if diluted by a further 7- to 14-fold in vitro. chrysinwasabletosuppresstheactivityofproinflammatory
Cooperetal.[90]continuedtheworkanddiscoveredthat17 enzymes, cyclooxygenase-2 (COX-2), and inducible nitric
strainsofpseudomonasisolatedfrominfectedburnwounds oxidesynthase(iNOs).Rasoetal.[95]discoveredthatseveral
could be killed by MH, even when diluted more than 10- flavonoids,includingquercetinand galangin,also inhibited
fold.HammondandDonkor[91]investigatedthebactericidal the expression of COX-2 and iNOs in a concentration-
effect of Clostridium difficile on MH. They found that the dependentmanner.
correspondingMICandminimalbactericidalconcentration Honeys from different botanical origins have different
(MBC) were both 6.25% (v/v). Kwakman et al. [81] further components. The following in vitro studies give a clear
discovered that the bactericidal activity of MH could kill picture of the anti-inflammatory action of MH. Henriques
Bacillus subtilis, P. aeruginosa, and E. coli. Maddocks et al. and colleagues [99] discovered that MH had the strongest
[87]identifiedthebactericidaleffectofMHonStreptococcus antioxidantcapacityamongthevarietiesofhoneythatwere
pyogenes in both planktonic cultures and biofilm. Apart testedandthatitwasabletoquenchtheaddedfreehydroxyl
from that, MH can also kill antibiotic-resistant bacteria. radicals within 5 minutes of being added. This antioxidant
Cooper et al. [92] found that seven strains of vancomycin- capacitycontributedtotheabilityofMHtoresolvechronic
resistanceEnterococciwereinhibitedbyMHat4.61±0.51% inflammations, including ulcers. In addition, Tonks et al.
(v/v). French et al. [93] demonstrated that MH inhibited [100] revealed that MH stimulated both the proinflamma-
18strainsofantibiotic-resistantcoagulase-negativeStaphylo- torycytokinesTNF-𝛼andIL-1𝛽andtheanti-inflammatory
cocciatdilutionsofdownto29.9±1.9%(v/v).Interestingly, cytokine IL-6 from monocytes. Tonks and his colleagues
MH has a synergistic antibacterial effect with antibiotics. [97] further found that a 5.8kDa component isolated from
Five antibiotics and MH combinations were found that MHstimulatedthesecytokinesviatoll-likereceptor(TLR)4.
improve antibacterial effectiveness in vitro [149]. However, AfterheattreatmentsugarsyruporMHlosesthisfunction.
MHcannotkillallmicroorganisms.Lusbyetal.[150]revealed This explains why supermarket honey cannot be used as
thatMHisunabletoinhibitSerratiamarcescensandCandida medicinal honey for treating wounds. van den Berg et al.
albicans. [47] also discovered that the phenolic constituents of MH
However, the effect of MGO in diabetic ulcers is debat- were able to inhibit the production of ROS and scavenge
able.PriceandKnight[151]pointedoutthatMGOchanged superoxideanion.Recently,researchersfromtheUniversity
the structure and function of immunological enzymes to of Waikato investigated the anti-inflammatory activity of
formAGEsandreducedtheefficiencyoftheperipheralblood MH in vitro. Bean [101] found that MH increased both the
immune-cellresponse.Majtan[152]furtherpointedoutthat expressionoftheproinflammatorycytokineTNF-𝛼andthe
manukahoneycontainshighlevelsofMGOandspeculated anti-inflammatory cytokines Il-10 and IL-1 and the growth
that patientswith diabetes may be placed at riskby the use factorsPDGFandTGF-𝛽.ROSproductionbyphagocytosis
of manuka honey because of its direct negative effect on was also downregulated in the presence of MH. These
cells or its indirect effect on the formation of AGEs, which findingsareinalignmentwithpreviousinvitrostudiesand
Evidence-BasedComplementaryandAlternativeMedicine 9
explain why MH may allow inflammation to proceed at a waspredictable,astheparticipantswereassignedtogroups
modulated level while simultaneously allowing healing to IandIIinanalternatemanner.Theinclusionandexclusion
occur. criteriawerenotclearlyreported.Althoughitwasfoundin
Leongetal.[102]determinedthatMHdecreasedthepro- both RCTs that MH was more effective than tulle dressing,
ductionofsuperoxidesbyneutrophilinvitroanddecreased wewerenotconfidentenoughtocometoasolidconclusion
odema and leukocyte infiltration in a mice model but were becauseofthehighriskofbiasinthedesignoftheresearch.
unable to pinpoint the specific content contributing to the Therefore, a high-quality study with a vigorously designed
inflammatoryaction.Tomblinetal.[98]furtherdiscovered RCTforDFUisneededtoenrichthebodyofknowledgein
thatthisanti-inflammatoryactivityofMHdirectlycorrelated thisarea.
to the phenolic content through a TLR1/TLR2 signalling
pathway.Thehigherphenoliccontentproducedanelevated
5.ComparisonofNanocrystalline
anti-inflammatory effect. This result echoed the findings of
SilverandManukaHoneyDressing
Leong et al. [102] on the specific content inside MH that is
responsiblefortheanti-inflammatoryfunction.Theantibac-
According to the review in the preceding sections, both
terialandanti-inflammatoryactionsofMHaresummarized
nAgandMHhaveclearantibacterialandanti-inflammatory
inTable3.
effects in vitro. In this section, we review the studies con-
ductedinthepast10yearscomparingtheantibacterialeffect,
4.3. The Clinical Evidence on the Use of MH on DFU. In
cytotoxicity(Table5),andclinicaleffectivenessofsilverand
DFU,thelocalfactorsthathinderwoundhealingareahigh
honey.
bioburdenandahighinflammatoryresponse.MHhasbeen
confirmed to have such properties in vitro. Unfortunately,
there is limited high-quality evidence to show its effect 5.1. Antibacterial Effect. Nasir et al. [106] conducted an in
in vivo. We reviewed single case studies, case series, and vitrostudytocomparetheantibacterialeffectofhydrofiber
randomizedcontrolledtrialsontheeffectofhoneyorrelated Ag(aquacelAg)andhydrofibersoakedwithmanukahoney.
productsthathadbeenpublishedinthepast10years.Sixsin- They found that that hydrofiber Ag had a greater zone of
glecasestudies[158–163],fivecaseseriesstudies[164–168], inhibition (ZOI) than MH for Gram-negative bacteria, but
onecontrolledtrial[169],andthreeRCTs[104,105,170]were nostatisticaltestwasperformedforthecomparison.Guthrie
foundonDFU.Variouskindsofhoneyproductswereapplied et al. [107] obtained a similar result. They carried out an
asinterventionsinthepublishedstudies. Differentkindsof animalstudyonamicetraumaticmodelcontaminatedwith
honeyhavevariousactiveingredientsandconcentrations,so S. aureus and revealed that the nAg group had statistically
theyhavebeenexcludedfromthepresentanalysis.Onlyone significantly lower bacterial counts than the MH group.
publishedcaseseriesstudy[103]wasfoundontheuseofMH However, Bradshaw [108] conducted an in vitro study and
inlegulcerationswithDFUandtwoRCTsonDFU[104,105] obtainedacontradictoryresult.Bradshawcompareddifferent
(Table4).GethinandCowman[103]reportedeightcaseson iodine, honey, and silver wound dressings and found no
the use of MH in leg ulcerations. Only one case involved significantoveralldifferenceinZOIamongthethreegroups.
DFU,whiletheothersinvolvedlegulcerationswithdifferent Nevertheless, a significant difference in ZOI was observed
etiologies.Theyrevealedthatthemeaninitialwoundsizewas between different types of Ag dressings against each bac-
2 2 terium. There could be several reasons for the inconsistent
5.62cm ,decreasingto2.25cm attheendofthefour-week
findings.First,thenatureofthedressingmaterials,asacarrier
study.Noinclusionandexclusioncriteriawerementionedfor
mediumtoholdtheactiveingredientofAgorhoney,might
thestudyandsubjecttoahighriskofdetectionbiasalthough
haveaffectedtheantibacterialactivity.Second,theoriginsof
theoutcomeassessorwasblinded.
thehoneyusedinthesestudiesdiffered.Third,thechemical
AlSaeed[104]performedanRCTusingMHimpregnated
natureofsilveranditsconcentrationsindifferentcommercial
dressing against tulle on DFU. The result showed that the
brandsvaried.
honey dressing was superior in terms of the proportion
In addition, Lund-Nielsen et al. [109] conducted a sin-
of healing, rate of amputation, and time to eradicate the
gle blinded RCT to study the qualitative bacteriology in
infection. Unfortunately, the methodology of the study was
malignant wounds using honey-coated and silver-coated
flawed. No report was made on how the randomization,
dressings.Nosignificantdifferenceswerefoundbetweenthe
concealment,anddoubleblindingwereperformed.Thecri-
groups.However,thisresultmaynotbegeneralizabletoother
teriaforinclusionandexclusioninthestudywerenotstated
types of wounds since malignant wounds are characterized
clearly.Theantibioticsthatwereusedandanyadverseevents
by continuous tissue deterioration with a large volume of
werenotreported.AccordingtotheCochraneCollaboration’s
necrotictissueandslough.Thismayleadtoahighbioburden.
“riskofbias”criteria[171],therewasanunclearriskofbias
in selection, performance, and detection. Kamaratos et al.
[105]performedanotherRCTusingMHtulleagainstsaline 5.2.Cytotoxicity. Surprisingly,theinvitrofindingscompar-
soaked gauze. The result was that the intervention group ingthecytotoxicityofsilverandhoneyareinconsistent,since
healedsignificantlymorequicklythanthecontrolgroup.An silverhaswell-knowncytotoxiceffect,asshowninprevious
unclearriskofdetectionbiaswasfoundinthattheblinding in vitro studies. Du Toit and Page [110] conducted an in
of the outcome assessors was not clearly reported. A high vitro comparison of both types of dressing with regard to
riskofselectionbiasrelatingtotherandomizationsequence thecellmorphologicaleffectsofkeratinocytesandfibroblasts.
10 Evidence-BasedComplementaryandAlternativeMedicine
on n ng
ble3:Modesofactionofmanukahoney. MajorfindingsonantibacterialactionPhysicalproperty Osmoticeffectcandrawwaterfrombacteriaanddehydratethem Acidity(pH3.2–5.5)caninhibitthegrowthofmostmicroorganismsActiveingredientHighconcentrationsofMGOrangedfrom38to828mg/kgascomparedwithnon-MHMGOrangingfrom38to761mg/kgcaninhibitE.coliandS.aureusat1.1mMMGOrangedfrom189to835mg/kgandwasdirectlyresponsiblefortheantibacterialpropertyGlycosideofmethylsyringatecalled“Leptosin”correlatedpositivelywithantibacterialactivityOtherthanMGO,cationicandnoncationiccompoundscontributedtoantibacterialactivityMechanismofactionHoney-treatedcellsfailtoproceedcelldivisionandseparation(i)S.aureus(ii)MRSAExtensivecelllysisonP.aeruginosaatMIC12%(w/v)after60minutesofexposuretoMHRibosomalfunctiononS.aureusinterferedincludingproteinsynthesis,themetabolicprocess,andtranscriptiInhibitionofthebindingofStreptococcuspyogenestofibronectinandthedevelopmentofbiofilmLimitP.aeruginosatocaptureironandimpedeitsgrowthBactericidalactivityondifferentmicroorganismsStreptococcuspyogenesPseudomonasspecies Clostridiumdifficile MRSA,Bacillussubtilis,E.coli,P.aeruginosaStreptococcuspyogenesVancomycin-resistantEnterococciAntibiotic-resistantstrainsofcoagulase-negativeStaphylococciMajorfindingsonanti-inflammatoryactionActiveingredientPinobanksin,pinocembrin,luteolin,andchrysinarethemajorflavonoidsfoundinMH;lowlevelsofquercetiandgalanginwerealsodetectedQuercetinandgalangininhibittheexpressionofCOX-2andiNOsinaconcentration-dependentmannerChrysinsuppressestheactivityofproinflammatoryenzymes𝛼𝛽5.8-kDacomponentisolatedfromMHstimulatestheproinflammatorycytokinesTNF-andIL-1andtheanti-inflammatorycytokinesIL-6viatoll-likereceptor(TLR)4Phenoliccontentisdirectlycorrelatedtotheanti-inflammatoryactivityofMHthroughaTLR1/TLR2signallipathway
a
T
s s
e e
di di
ofstu view view vitrovitrovitrovitrovitro vitro vitrovitrovitrovitro vitrovitro vitro vitrovitrovitrovitroofstu vitro vitrovitro vitro vitro
ure Re Re InInInInIn In InInInIn InIn In InInInInure In InIn In In
at at
N N
Authors M.D.MandalandS.Mandal,2011Molan,2001 Adamsetal.,2008Mavricetal.,2008AtrottandHenle,2009Kwakmanetal.,2011Katoetal.,2012 Henriquesetal.,2010Jenkinsetal.,2011Robertsetal.,2012Packeretal.,2012Maddocksetal.,2012Krondaetal.,2013 Cooperetal.,1999Cooperetal.,2002HammondandDonkor,2013Kwakmanetal.,2011Maddocksetal.,2012Cooperetal.,2002Frenchetal.,2005Authors Chanetal.,2013 Rasoetal.,2001Choetal.,2004 Tonksetal.,2007 Tomblinetal.,2014
r r
e e
b b
m m
Nu 76] 77] 78]79]80]81]82] 83]84]85]86]87]88] 89]90] 91] 81]87]92]93]Nu 94] 95]96] 97] 98]
[ [ [[[[[ [[[[[[ [[ [ [[[[ [ [[ [ [