semut jepang

SEMUT JEPANG (TENEBRIO MOLITOR)APAKAH SEMUT JEPANG ITU ?Istilah SEMUT JEPANG sudah banyak digunakan oleh masyarakat, tapi sebenarnya tidak mencirikan sebagai semut. Lebih cocok disebut kutu berasTenebrio Molitor.Perbedaan dari semut Jepang dibandingkan semut spesies lainnya yakni memiliki badan yang keras, bersayap namun tak bisa terbang, suka reproduksi, hidup secara berkelompok, bukan hewan kanibal.Sumber :http://semutjepangdibogor.blogspot.com/2015_02_01_archive.html

BBPPTP Ambon, Ulat tepung (Tenebrio molitor) dikenal juga oleh kebanyakan masyarakat sebagai ulat hongkong. Imago dari serangga ini berupa kumbang yang termasuk dalam genusTenebrioyang memiliki warna merah kehitaman, hitam atau coklat gelap dan panjangnya 13-17 mm (Borroret al.,1982).Sumber :http://ditjenbun.pertanian.go.id/bbpptpambon/berita-309-tenebrio-molitor-hama-pascapanen-yang-bermanfaat.html

Ciri dari semut jepang ini secara umum adalah memiliki tubuh berwarna hitam kecoklatan, berkaki enam dan tekstur tubuhnya cenderung keras. Hewan ini memiliki sayap yang mirip dengan kumbang. Namun semut jepang tidak dapat terbang seperti serangga bersayap lainya.Sumber :http://mulaiusaharumahan.blogspot.com/2014/10/cara-budidaya-semut-jepang.html

Keunikan khas Semut jepangSemut jepang memiliki ciri atau tanda seperti:1. Suka atau cepat berkembangbiak2. Hidup berkoloni atau berkelompok3. Ruas badan lebih besar dari ruas kepala4. Ukuran tubuh kecil hanya beberapa milimeter5. Bukan tipe hewan pemakan daging/sesama6. Memiliki sayap tapi tidak bisa terbang7. Makanan ragi tape8. Memiliki badan yang keras,9. Memiliki kaki 6Sumber :http://www.mearindo.com/2014/11/semut-jepang-solusi-untuk-asam-urat.html

Manfaat dan kegunaan dari semut Jepang menuruthttp://tipsdantrikampuh.blogspot.com/2014/09/manfaat-dan-kegunaan-dari-semut-jepang.html,adalah : Semut Jepang berguna untuk menjadikan tingkat kolesterol di darah normal, khususnya untuk orang yang mempunyai kadar kolesterol tinggi pada darah. Mengobati dan meringankan penyakit jantung. Mengobati dan meringankan penyakit asam urat, khusus orang dengan kadar asam urat tinggi di tubuh. Menjadikan jumlah gula di darah menjadi stabil, cocok untuk orang yang terserang penyakit diabetes. Menjadikan tekanan darah stabil, khususnya untuk orang yang menderita hipertensi (penyakit darah tinggi). Mampu menambah vitalitas dari pria maupun wanita, cocok bagi pria maupun wanita dengan jam kerja tinggi serta kesibukan untuk sehari-harinya, tubuh pun dapat menjadi lebih segar dengan semut Jepang.Manfaat semut Jepang berdasarkan kajian ilmiah, kami paparkan sebagai berikut :-------------------------------------------------------------

Sumber :http://en.cnki.com.cn/Article_en/CJFDTOTAL-HBNS200201007.htm

Hasilnya penelitian menunjukkan bahwa fungsi Tenebrio molitor pada tikus adalah dapat meningkatkan pertumbuhan, meningkatkan kemampuan belajar dan menghafal serta merupakan anti kelelahan dan kekurangan oksigen dan meningkatkan intelegent.


Hasilnya penelitian menunjukkan bahwa Tenebrio molitor merupakan protein alami berkualitas tinggi, namun penggunaannya baru sebatas hal yang terkait dengan kesehatan - karena keterbatasan teknologi.


Sumber :http://en.cnki.com.cn/Article_en/CJFDTOTAL-SPKJ200904103.htm------------------------------------------------------------

------------------------------------------------------------Characteristics of Maize Flour Tortilla Supplemented with GroundTenebrio molitorLarvaeErick D. Aguilar-Miranda,Mercedes G. Lpez,Clara Escamilla-Santana,andAna P. Barba de la Rosa*Instituto Tecnolgico de Celaya, Avenida Tecnolgico s/n, Celaya, Guanajuato 38010, Mxico;Departamentode Biotecnologa y Bioqumica, CINVESTAV-IPN, Km. 9.6 Libramiento Norte Carretera Irapuato-Len, Irapuato, Guanajuato 36500,Mexico; and CES Internacional and Asociados, Cirilo Conejo 6,Quertaro, Quertaro, Mxico

AbstractThe larva of theTenebrio molitor, known as the yellow mealworm, is a plague of wheat and flours. Consumption of the raw insects is not well accepted because of their appearance. The objective of the present work was to growT. molitorlarvae under standard conditions, to analyze the chemical composition of the larvae powder, and to prepare supplemented maize tortillas. Protein and fat contents were performed with standard methods.Tenebriolarvae powder had a 58.4% protein content; this protein was rich in essential amino acids such as phenylalanine, tyrosine, and tryptophan; the found values satisfied those recommended by the Food and Agriculture Organization. Fatty acid composition was determined by GC-MS showing high contents of oleic acid and linoleic acid (19.8 and 8.51%, respectively). A large proportion of unsaturated fatty acids of longer chains was detected.Long-chain fatty acids having two or three double bonds have been claimed as highly beneficial to health. Tortillas supplemented with larvae powder had excellent consumer acceptance, and tortilla protein content increased by 2% as well as the amount of essential amino acids.These results show new ways to consume insects and at the same time increase the nutritional value of the original food products.

Sumber : http://pubs.acs.org/doi/pdf/10.1021/jf010691y---------------------------------------------------------------------------Energy-efficient food production to reduce global warming and ecodegradation: The use of edible insectsShri Manakula Vinayagar College of Engineering and Technology, Puducherry, India.AbstractAs the global population continues to rise, and attempts to increase arable land area come in sharp conflict with the necessity to retain forests on one hand and pressures of urbanization on the other, the wave of global food shortage that has hit the world recently is likely to hit us again and again.The increasing pressure on land is making meat production from macro-livestockless sustainable than ever before. To add to the diminishing pastures and broadening demand-supply gap of food grains are the shortages arising due to the diversion of some of the food crops for biofuel production. There is also an increasing use of fodder for generating biomassenergy. The result is that even as the demand for animal protein keeps on rising with the swelling global population, there is every possibility that attempts to meet this demand would face serious crises in the coming years. The adverse impacts of global warming areconspiringto make the situation even worse than it otherwise would have been.The present review brings home the fact that one of the possible ways to get around this problem is to extend the practice of entomophagy use of insects as human food. As of now entomophagy is practiced in someregionsand some cultures, but, by-and-large, the bulk of global population stay away from it. It is even looked down in several cultures and forbidden in some others. The review brings out the irrationality of omitting edible insects from humandietgiven the generally higher quality of nutrition they contain as compared to food based on macro-livestock. This aspect, coupled with much lesser consumption of energy and natural resources associated with insect-based protein production, makes entomophagy an option which deserves urgent global attention.The authors highlight the relatively stronger sustainability of animal protein production by way of insect farming because, pound to pound, the production of insect protein takes much less land and energy than themorewidely consumed forms of animal protein. It is estimated that over a thousand insect species are already a part of human diet and the nutrition offered by several of the species matches or surpasses that which is contained in traditional non-vegetarian foods. The paper also deals with the relevance of entomophagy as a potentially more ecologically compatible and sustainable source of animal protein than the red and the white meat on which most of the world presently depends. In the emerging global pattern based on an expanding share of renewable energy sources, entomophagy fits in as a renewable source of food energy for the future.------------------------------------------------------------

Larvae of mealworm (Tenebrio molitor L.) as European novel food

Copyright 2013 Ewa Siemianowska et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

ABSTRACT

Forcenturies,insectshavebeenusedas food duetotheiravailabilityandeasinessinraising thatismuchlessburdensomefor environment thananimalhusbandry breeding.Mealworm (TenebriomolitorL.) is a store-pest ofwhich larvaeareconsumedby people.Theaimoftheworkwastodeterminethenutritionalvalueof larvae of mealworm (Tenebrio molitorL.). The materialwasathree-month-oldmealwormlarva 25-30mminlength.Larvaewereboiledfor3minandnextdriedin60C.Contentsofwater,ash, minerals, protein, fat and fat acids profile have beendetermined.Freshlarvaecontained56%ofwater,18%oftotalprotein,22%oftotalfatand 1.55%ofash.Highcontentsofmineralswere foundinthe larvae:magnesium(87.5 mg/100g), zinc (4.2mg/100g), iron (3.8 mg/100g),copper (0.78 mg/100g) and manganese (0.44 mg/100g). Theproportionofn-6/n-3fatty acidswasvery advantageousandamounted to6.76.Larvae powder containedtwice highercontentofprotein, fat, ashand minerals. Larva of mealworm is avaluable source of nutrients in amounts more profitable forhumanorganismthan traditional meatfood. Powdered larvaisahigh-grade producttobeappliedas asupplementtotraditional meals.

-----------------------------------------------------------AdigestiveprolylcarboxypeptidaseinTenebriomolitorlarvae

IrinaA.Goptara,DmitryA.Shaginb,c,IrinaA.Shaginac,ElenaS.Mudrikc,YuliaA.Smirnovad,DmitryP.Zhuzhikove,MikhailA.Belozerskyd,YakovE.Dunaevskyd,BrendaOppertf,*,IrinaYu.Filippovaa,ElenaN.Elpidinad

aChemicalFaculty,MoscowStateUniversity,Moscow119991,RussiabShemiakinandOvchinnikovInstituteofBioorganicChemistryRAS,Miklukho-Maklaya16/10,117997Moscow,RussiacEvrogenJSC,Miklukho-Maklaya16/10,117997Moscow,RussiadA.N.BelozerskyInstituteofPhysico-ChemicalBiology,MoscowStateUniversity,Moscow119991,RussiaeBiologicalFaculty,MoscowStateUniversity,Moscow119991,RussiafUSDAAgriculturalResearchService,CenterforGrainandAnimalHealthResearch,1515CollegeAve.,Manhattan,KS66502,USA

ABSTRACTProlylcarboxypeptidase(PRCP)isalysosomalprolinespecicserinepeptidasethatalsoplaysavitalrole intheregulationofphysiologicalprocessesinmammals.Inthisreport,we isolateandcharacterizethe rstPRCPinaninsect.PRCPwaspuriedfromtheanteriormidgutoflarvaeofastoredproductpest,Tenebriomolitor,usingathree-stepchromatographystrategy,anditwasdeterminedthatthepuried enzymewasadimer.ThecDNAofPRCPwasclonedandsequenced,andthepredictedproteinwas identicaltotheproteomicsequencesofthepuriedenzyme.Thesubstratespecicityandkineticparametersoftheenzymeweredetermined.TheT.molitorPRCPparticipatesinthehydrolysisof theinsectsmajordietaryproteins,gliadins,andis therstPRCP tobeascribedadigestivefunction.Our collectivedatasuggestthattheevolutionaryenrichmentofthedigestivepeptidasecomplexininsects withanareaofacidicto neutralpHinthe midgutisaresultoftheincorporationoflysosomalpeptidases, includingPRCP.

Introduction

Prolylcarboxypeptidase(PRCP;PCP,lysosomalcarboxypeptidase, angiotensinaseC,EC3.4.16.2)belongstoagroupofprolinespecic peptidases(PSP)(CunninghamandOConnor,1997)thatareinvolvedintheregulationofvarious metabolicprocesses(Vanhoofetal.,1995).PSPrepresentarelativelysmallgroupofhighlyspecicexo-and endo-peptidasesthatcleave bondsformedbyprolineresiduesin proteinsandpeptides.Theunique activityofPSPisduetothe structuralfeaturesofproline,theonlycycliciminoacidamong20aminoacidsfoundinproteinsandpeptides.Peptidebondscontaining prolineresiduesarenothydrolyzedefcientlybymostpeptidases, andaprolineresidueinthepeptidechainservestoprotectagainst degradationbyenzymeswithbroadspecicity.TheabilityofPSPtohydrolyzethisbonddeterminesthespecicactivityoftheenzymein theregulationofmetabolicprocesses.PRCPareserinepeptidasesthatcatalyzethe cleavageofasubstrate attheC-terminalaminoacid linkedtoaprolineresidue.Atpresent, onlyPRCPfromhuman(Odyaetal.,1978;Tanetal.,1993;Shariat-Madaretal.,2002),pig(Yangetal.,1970;Kakimotoetal.,1973),monkey(Suzawaetal.,1995),andbacteriumXanthomonasmalto-philia(Sugaetal.,1995)havebeenisolatedandstudied.Theprimary structureoftheisolatedenzyme,presentasadimerinsolution,has beendescribedonlyforhumanPRCP,andtheenzymewasassignedto theS28familyof serinepeptidases(Tanetal.,1993).Thecrystal structurewassolvedrecentlyandrevealedthatPRCPhasaunique peptidasestructure,withclosestidentitytodipeptidylpeptidase7 (DPP7),containingaconserveda/bhydrolasedomainandanovel helicalSKSdomainthatcapstheactivesitewiththecatalyticSer-Asp-Histriad(Abeywickremaetal.,2010;Soissonetal.,2010).PRCPis widelydistributedinhumantissues,butmostlyitis localizedtothelungs,liver andplacenta(Tanetal.,1993).Theenzymewasinitiallyfoundinhumanlysosomes(Yangetal.,1970;Kumamotoetal.,1981), butlateritwasfoundasa membrane-expressedenzymein culturedhumanumbilicalveinendothelial cells,explainedbytheassociationofPRCPwithspecicmembrane proteinsafterexocytosis(Shariat-Madaretal.,2004).Theexactphysiological functionsforPRCParenotcompletely understood.Thekeyrole formammalianPRCPisinregulating bloodpressure(Kumamotoetal.,1981;Tamaokietal.,1994;KaplanandGhebrehiwet,2010;Hagedorn,2011),butPRCPisalsoinvolved inprocesses of proliferation(Duanetal.,2011),inammation(Kumamotoetal.,1981;Ngoetal.,2009)andangiogenesis(Mallelaetal.,2009).PRCPalsoregulatesfood intakebyinactivatinga- melanocytestimulatinghormone(Wallingfordetal.,2009;Shariat-Madaretal.,2010;Diano, 2011;Jeongetal.,2012).Theonlyreport ofinsectPRCPdetailschangesinexpressionofthePRCPgenein responsetomagnesiumexposurein Culexquinquefasciatuslarvae (Zhaoetal.,2010).ThepresentresearchoninsectPSPisapartofourstudies of digestiveenzymesinlarvaeoftheyellowmealworm,Tenebrio molitor(Coleoptera:Tenebrionidae),apestofprocessedgrainsand storedproducts.ThecomplexofdigestivepeptidasesinT. molitor larvae differs substantiallyfromhumandigestive enzymes, althoughboththebeetleandpeople havegrainproductsasapri- maryfoodsource.Themajordigestiveorganofthelarvae isthe midgut,whereasharppHgradientisfound,from5.6intheanterior midgut(AM)to7.9inposteriormidgut(PM)(Terraetal.,1985;Vinokurovetal.,2006a;ElpidinaandGoptar,2007).Thisgradient restricts theactivityofdifferentdigestiveenzymesinspecic compartmentsofthemidgut,whichisusuallyconsistentwiththe pH-optimaoftheiractivity(Vinokurovetal.,2006b).Themajor digestivepeptidasesintheAMofT.molitorlarvaeare cysteinepeptidases,represented byfourtosixdistinctenzymes (TerraandCristofoletti,1996;Vinokurovetal.,2006a,b;Prabhakaretal.,2007).Themajorcysteinepeptidaseactivity iscathepsinL (Cristofolettietal.,2005;Betonetal.,2012;Oppertetal.,2012)knownasalysosomalpeptidaseineukaryotes(Turketal.,2012).InthePMofT.molitorlarvae,digestiveenzymesaremostlyserine peptidases,includingfourtrypsin-like andvechymotrypsin-like serine peptidases (Tsybinaetal.,2005;Elpidinaetal.,2005;Vinokurovetal.,2006a,b)aswellasamembrane-boundamino- peptidase(Cristofoletti andTerra,1999,2000)andsolublecarboxypeptidase(Ferreiraetal.,1990;Prabhakaretal.,2007).Themajor dietaryproteinsofT.molitorlarvae,prolamins, contain30-50%glutamine and10-30%prolineresidues(ShewryandTatham,1990;ShewryandHalford,2002).Therefore,weanalyzedthemajorpost-glutaminecleavingactivitiesintheT. molitorlarvaldigestive complexandfoundthattheywere cysteinepeptidases(Goptaretal.,2012).Basedonthecomposition oftheirdiet,wealsopredictedtheoccurrenceofdigestivePSPinT.molitorlarvae.Indeed,we describedtherstproline-specic digestivepeptidaseinthemidgut,whichwasaserinepeptidase thatspecicallycleavedafterproline,hadanacidicpHoptimum (5.3),andwasfoundmainlyintheAMcontents(Goptaretal.,2008a,b),buttheenzymewasnotidentied.Inthepresentstudy, weidentifythisenzymeasaPRCPanddetailthesubstratespeci- cityandkineticparametersoftherstpuriedPRCPinaninsect. OurdatasuggestthatPRCPisadigestiveenzymeinT. molitorlarvae, whichisanovelfunctionforPRCP.

Discussion

Inthispaper,therstPRCPwasisolatedfromaninsect,T. molitor larvae.ForPRCP purication,athree-stageschemewasused.The rststagewasbygelltration.Theapplicationof thistypeof chromatographyeffectivelyseparatedPRCP,withamolecularmass of105kDa,fromthemajordigestiveserineandcysteineendo- peptidases,withmolecularmasseslessthan40kDa(Vinokurovetal.,2006b)andthereforepreventedproteolysisby endopepti- dasesduringpurication.Additionalpuricationfollowedwith anionexchangeandhydrophobicchromatography,resultingin a relativelypureenzyme.ThecDNAoftheT.molitorlarvalPRCPwas clonedandsequenced, andtheidentityof thepredictedPRCP sequencetotheprimary structureoftheisolatedenzymewas conrmedbymassspectrometry.TheratioofthecalculatedmolecularmassofclonedPRCPandthatdeterminedbygelltration suggeststhattheenzymeisadimer,andsimilardataarereported forthehumanlysosomalPRCP(Odyaet al.,1978;Tanetal.,1993).AlsosimilartothehumanPRCP,T.molitorPRCPdisplaysacidicpH optimumatpH5.6,correlatingwithitslocalizationintheacidicAM ofT.molitorlarvae(Goptaretal.,2008b).Previously,theprimarystructureoftheenzymewassolvedonly forhumanPRCP,andtheenzymewasassignedtotheS28familyof serinepeptidases(Tanetal.,1993).WhenPRCPwascomparedwith annotatedsequencesof serinecarboxypeptidases andPOP,therewasalowdegreeof overallidentity(10e18%),butahigh(67%) identityinactivesiteaminoacidresidues.The authorsconcluded thatPRCPisanevolutionarylinkconnectingtwofamilies,POPand serinecarboxypeptidases, becausetheypossesspropertieschar- acteristic ofbothfamilies.Likeserinecarboxypeptidases,PRCP catalyzesthehydrolysisofaC-terminalresiduethathas afree carboxylgroupatacidicpHvalues.Ontheotherhand, PRCPhy- drolyzesbondsformedbythecarbonylgroupofprolineresiduesas doPOP,andaspecic inhibitorofPOP,Z-Pro-prolinal,inactivates PRCP aswell.Resolutionofthe2.8Acrystalstructureofthehumanlysosomal PRCP(Soissonetal.,2010)delineatedthestructuralbasisofthe differentsubstratespecicitiesofthetwoenzymescomprisingthe uniqueS28 familyofPSP:carboxypeptidasePRCPandaminopep- tidaseDPP7. PRCPhasanextendedactive-site cleftthatcan accommodateprolinesubstrateswithmultipleN-terminal resi- dues.Incontrast,thesubstratebindinggrooveofDPP7isoccluded byashortaminoacid insertionuniquetoDPP7thatcreatesa truncatedactive siteselectivefordipeptidylproteolysisofN-ter- minalsubstrates.ThemostspecicsubstrateforT.molitorPRCPwasN-protected peptideZ-PF,aselectivesubstrateforPRCP,buttheactivityassay withthissubstratewasrather complicated. Becauseserine carboxypeptidases,unlikemetallocarboxypeptidases,are abletohydrolyzechromogenicp-nitroanilidesubstrateswithadetectable rate(Scheeretal.,2011),andduetothesimplicityoftheassay method,weusedthesesubstratesfor monitoringofthepurica- tionprocessandforthestudyofthesubstratespecicity.Thebest chromogenic peptidesubstratewasZ-AAP-pNAwiththehighest Vmax/Kmvalue,despitethefactthatthesubstrate hadthelowestKmvalue.ThehydrolysisofsubstratesZ-AP-pNAandAP-pNAoccurredwith equalefciency,althoughZ-AP-pNAwasmore tightlyboundtotheenzyme,andAP-pNAwashydrolyzedfaster. Lengtheningorshortening thesubstrateby oneAlaresidue, substitutingAlaatGly,aswellasremovingtheN-protectinggroup allledtoanincreaseoftheKm.Themaximumrateofhydrolysisof Z-GP-pNA,aspecicsubstrateforPOP(CunninghamandOConnor,1997)andZ-P-pNAwasanorderof magnitudelower thanfortheothersubstrates.KineticstudiesrevealedcompletecompetitiveinhibitionofT.molitorPRCPbyZ-Pro-prolinal.Inthistypeofinhibition,thein- hibitorinteractswiththesameregionof theenzymethatbinds substrate.Thereforetheinhibitorcompeteswiththesubstratefor interactionwiththeenzyme,asdoothersubstrate-likeinhibitors similartoZ-Pro-prolinal.IncontrasttohumanPRCP,whichspecically functionsasa regulatoryenzymeaffecting thebloodsystem(Hagedorn, 2011;Adamsetal.,2011),thePRCPfromT.molitorispresumablya digestiveenzyme.Earlier,wedescribedthelocalizationandfunc- tionsoftwoPSPsfromT.molitorlarvae(Goptaretal.,2008a,b).WedemonstratedthatoneofthePSPshadanacidicpHoptimum,was localizedintheAM contents,andtheactivityprolechangedinthe digestiveprocesssimilartothegeneralproteolyticactivity, but thesedatawereinsufcient forconclusiveidenticationofthis peptidase.In thisreport,weidentiedthisenzymeasPRCPand furtherdemonstratethatT.molitor larvalPRCPparticipatesin gliadinhydrolysisthatisreducedbyaspecicinhibitorofPRCP Z- Pro-prolinal.Thus,we haveisolated,puried,andidentiedtheprimary structureandfurthercharacterizedadigestivePRCPfromthelarval midgutof aninsectpest,T.molitor.Theuniqueaspectsofthis enzymearethatitistherstPRCPisolated fromaninsect,andthe rstPRCPfoundtofunctionas asecreteddigestiveenzyme.Itis unknownifPRCPisinvolvedindigestioninotheranimals.Specic digestivepeptidasesininsectsthatdifferentiatethemodeofgliadinhydrolysisfromthatofhumanincludecysteinepeptidaseswith post-glutamine cleavingactivity(Goptaretal.,2012),andPRCP withpost-prolinecleavingactivity(thisreport).Ineukaryoticorganisms,theseenzymesparticipateintheintracellularlysosomal degradationofproteins.Manyinsectsrelyontypicalserinedigestivepeptidases,trypsinandchymotrypsin,butsomegroupsofinsectswithanareaofacidictoneutralpHinthemidgutusecysteine cathepsinsalsofor digestion(TerraandFerreira,1994).Ourdata suggestthattheenrichmentofthepeptidasedigestivecomplexin suchinsectsduringevolutionisduetotheadaptationofpeptidases presentinthelysosomesofeukaryoticorganisms,such ascysteine cathepsinsandPRCP.

-----------------------------------------------------------------------------APAKAH "Prolylcarboxypeptidase" itu ?

Carboxypeptidasesikat enzim perbatasan pankreas yangmembagi satu asam amino pada suatu waktu.---------------------------------------------------------

Supplementation ofl-carnitine in athletes:does it make sense?HeidrunKarlic,PhD,andAlfredLohninger,PhDFromtheLudwigBoltzmannInstituteforLeukemiaResearchandHematology,Vienna, Austria;andtheDepartmentofMedicalChemistry,UniversityofVienna,Vienna,AustriaAbstractStudies in athletes have shown that carnitine supplementation may foster exercise performance. As reported in the majority of studies, an increase in maximal oxygen consumption and a lowering of the respiratory quotient indicate that dietary carnitine has the potential to stimulate lipid metabolism. Treatment withl-carnitine also has been shown to induce a significant postexercise decrease in plasma lactate, which is formed and used continuously under fully aerobic conditions. Data from preliminary studies have indicated thatl-carnitine supplementation can attenuate the deleterious effects of hypoxic training and speed up recovery from exercise stress. Recent data have indicated thatl-carnitine plays a decisive role in the prevention of cellular damage and favorably affects recovery from exercise stress. Uptake ofl-carnitine by blood cells may induce at least three mechanisms: 1) stimulation of hematopoiesis, 2) a dose-dependent inhibition of collagen-induced platelet aggregation, and 3) the prevention of programmed cell death in immune cells. As recently shown, carnitine has direct effects in regulation of gene expression (i.e., carnitine-acyltransferases) and may also exert effects via modulating intracellular fatty acid concentration. Thus there is evidence for a beneficial effect ofl-carnitine supplementation in training, competition, and recovery from strenuous exercise and in regenerative athletics.Correspondence to: Heidrun Karlic, PhD, Ludwig Boltzmann Institute for Leukemia Research and Hematology, Hanusch Hospital, H. Collinstr. 30, A-1140 Vienna, Austria.

INTRODUCTIONDietary supplements to improve performance are familiar to many athletes. Manufacturers more or less aggressively claim that the substances improve the performance of athletes (i.e., act as ergogenic aids) and/or speed up their recovery from exercise. Most of these claims are purely speculative and based on assumptions about how the dietary supplement influencesmetabolism.The substance L-carnitine has been particularly popular as a potential ergogenic aid because of its role in the conversion of fat into energy.1,2Forascheme,thereaderisreferredtoFigure1.L-carnitine was firstdiscovered in muscle extracts by two Russian scientists3who named the substance for the Latin wordcarnis(fleshormeat).Itschemicalstructurewasestablishedin1927, and in 1935 a pioneer article about L-carnitine was published,4whichtriggerednumerousstudiesonthephysiological functions of the chemical.In 1959 Fritz showed that carnitine increases long-chain fatty oxidation in liver and heart.5Another nameforL-carnitinewasvitaminBT(Ttenebrio)becausethe larvaofblackbeetleTenebriomolitor(Tenebrionidae,Coleoptera) requiresL-carnitineasagrowthfactorinadditiontofolicacid and other known B vitamins. Considering the chemical structure, the choline-like metabolite L-carnitine(3-hydroxy-4-N,N,N- trimethylaminobutyrate, L-3-hydroxy-4-N-trimethylaminobutyric acidor-trimethylamino--hydroxybutyricacid)isaquaternaryamine.Inphrenicnervediaphragmpreparations,itseffect,namely inductionoftetanicfade,canbereducedbyadditionofcholine.6

FIG. 1. Role ofL-carnitine in oxidative metabolism.L-carnitines primary function (blue arrows) is to shuttle fatty acids into the mitochondria by CPT-I.CPT-IImediatesthefurtherprogressiontoward-oxidation.Car- nitinessecondaryfunctionaffectstheCoASH/CoAratio.CoASHisa two-carbon compound; CoA is a vitamin B derivative. SupplementalL-carnitine can react with some of the excess CoASH groups that accu- mulate during strenous exercise, thereby producing acetylcarnitine. This lowers the CoASH/CoA ratio, which in turn activates the enzyme PDH. PDH causes some pyruvate to be converted to CoASH as opposed to lactic acid. Less lactic acid can mean delayed fatigue. Further,L-carnitine reacts with the excess CoASH/CoA groups to form acetylcarnitine (green arrow), freeCoAisreleased.FreeCoAisnecessaryforcontinuousoperationofthe Krebscycle.Moreover,stimulatingPDHenhancesflowthroughtheKrebs cycle; as a consequence, maximum oxygen capacity (the capacity for aerobicregenerationofadenosinetriphosphate)isincreased.Togetherwith a decreased respiratory quotient (the quotient of exhaled CO2equivalents per inhaled O2),this can mean increased exercise performance. CoA, coenzyme; CoASH, CoASH, acetyl coenzyme A; CPT, carnitine palmi- toyltransferase;PDH,pyruvatedehydrogenase.

The function that has been investigated most thoroughly scientifically isthecarnitine-dependenttransportoffattyacids through the inner mitochondrial membrane.Other established functionsofL-carnitinearethepreservationofmembraneintegrity, the stabilization of a physiologic coenzyme A (CoA) acetyl-CoA (coASH) ratio in mitochondria, and the reduction of lactate production.7,8In vitro investigations have strongly supported the notionthatL-carnitineisabletoinhibitapoptosis(programmed celldeath)911(Figure2).

The intracellular homeostasis of carnitine is controlled by different membrane transporters. The organic cation transporters (OCTNs), in particular OCTN2, physiologically the most important,operateonintestinalabsorptionandrenalreabsorptionof L-carnitine and play a major role in tissue distribution and varia- tions in transport rates.Inborn or acquired defects on this carnitine transport mechanism lead to primary or secondary carnitine deficiency. The OCTN2 mRNA content of cells is reduced with aging12and by oxygen radicals.13OCTN2 is directly inhibited by several agents and substances known to induce systemic carnitine deficiency.Secondary carnitine deficiencyis often seen in patients on regular hemodialysis,14with metabolic disorders, and in pregnancy.15L-carnitine, widely available over the counter, is also favored among athletes.Rumors that L-carnitine supplementation helped theItaliannationalsoccerteamtowintheworldchampionshipin 1982 contributed immensely to its popularity.The most important claim relates to the role of carnitine in fat metabolism.L-carnitine isoftenadvertizedtoimprovefatmetabolism,reducefatmass,and increasemusclemass.Inotherwords,thesubstanceisportrayedas a fat burner. Therefore, carnitine is often recommended for conditions in which weight loss is indicated.Endurance athletes use carnitine to increase the oxidation of fat during exercise and spare muscle glycogen. This review critically examines whether theclaimsassociatedwithL-carnitinearejustified.

ROLEOFCARNITINEINFATMETABOLISML-carnitine plays an important role in fat metabolism.In the overnight-fasted state, during the resting state, and during exercise oflowtomoderateintensity,longchainfattyacidsrepresentupto 80%oftheenergysources.Thebestdescribedfunctionof L-carnitine is in its role as a cofactor of carnitine, acyltransferases transporting long-chain fatty acids across the mitochondrial inner membrane.21In the absence of L-carnitine, the inner mitochondrial membrane would be impermeable to long-chain fatty acids and fattyacyl-CoAesters.Onceinsidethemitochondria,thesecompoundscanbedegradedtoacetyl-CoAthroughaprocessknownas oxidation.Carnitinealsoplaysadecisiveroleinmaintainingthe acetyl CoA/CoA ratio in the cell. During high-intensity exercise, there is a large production of acetyl-CoA. This increase in turn inhibits the pyruvate dehydrogenase (PDH) complex and reduces fluxthroughthePDHcomplex.22Asaconsequence,acetyl-CoA gives rise to lactate. Acetyl-CoA reacts with free carnitine to form acetyl-carnitineandCoA.

Carnitinethereforemaysupresstheaccumulationoflacticacid, thereby enhancing high-intensity exercise performance.This has beenconfirmedinseveralstudies,whicharesummarizedinTable I. Results from a pilot study in patients with the human immuno- deficiency virusreceivingnucleosideanalogtherapyhavesug- gested that L-carnitine may be helpful for patients who have nucleoside analogrelated lactic acidosis with blood lactate levels higherthan10mM/L.23Sweeneyetal.24showedthatadditionof L-carnitinemayimprovethequalityofplateletconcentratesthat arestoredbeyond5dbyprovidingbetterpHpreservation,less glucoseconsumption,andlesslactategeneration.

Historically, skeletal muscle was seen mainly as the site of lactate production during contraction, and lactate production was associatedwithinsufficientmuscleoxygenationandconsequently fatigue.Later,itwasrecognizedthatskeletalmusclesnotonlyplay animportantroleinlactateproductionbutalsoinlactateclearance, and this improved understanding has led to a renewed interest in the metabolic fate of lactate in skeletal muscle and other tissues. Tracing studies using radioactive labeled lactate have shown that skeletal muscle extracts lactate from the circulation despite a substantial net lactate release, and that skeletal muscle has a large capacity for lactate oxidation; these processes are enhanced with exercise.

Diposkan olehM. Misbachul Munirdi19.04

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