Inqaku
I-methylene blue njenge-antioxidant nanjenge-pro-oxidant: yintoni etshintsha isiphumo?
Masithi iilabhoratri ezimbini zivavanya idayi enye eluhlaza okwesibhakabhaka zize zinike ingxelo yeziphumo ezichaseneyo. Kweyokuqala, iimitokhondriya zobuchopho ezahluliweyo ziphefumla ngcono zize zenze i-ATP engakumbi. Kweyesibini, loo sampulu inye ikhupha iperoksayidi yehayidrojeni engakumbi kakhulu. Zombini iingxelo zichanile. Zichaza umjikelo omnye ojongwe kumacala amabini, yaye ukudideka kuqala xa abafundi bethatha elinye icala njengengcaciso epheleleyo.
Impazamo kukubuza ukuba yeyiphi ileyibhile efanele le molekyuli. I-methylene blue isisidluliseli see-elektroni, njengoko imephu yezinto ejolise kuzo kwibhayoloji yeeseli ibonisa kumxholo obanzi. Idayi ekwimeko eneoksideshini yamkela ii-elektroni ize ibe yi-leucoMB engenambala. I-leucoMB idlulisela ezo elektroni kwenye indawo ize iphinde ibe luhlaza okwesibhakabhaka. Into oyibonayo ixhomekeke kulowo unikela ngee-elektroni, kulowo uzamkelayo, nasekubeni inkqubo iyakwazi na ukususa iperoksayidi yehayidrojeni eyenziwa endleleni. Umbuzo ofanele ukubuzwa awukokuba idayi iyi-antioxidant na. Kukuba iimeko zivumela esi sidluliseli ukuba senze ntoni.
Umjikelo ovelisa omabini amacala
Ebumnyameni, umjikelo osisiseko umfutshane. I-NADH, i-NADPH, okanye izithwali ezikwikhonkco lokuphefumla zinika idayi ii-elektroni, ziyinciphise. Idayi ekwimeko encitshisiweyo ineendlela ezikhuphisanayo zokuphuma kuloo meko. Inokudlulisela ii-elektroni kwi-cytochrome c ize ixhase ukuhamba kwazo ngendlela edlula ecaleni kwekhompleksi eyonakeleyo; yiyo loo nto ukuphefumla nomahluko wombane kwinwebu kubuyela ngokuyinxenye xa ikhompleksi I okanye III ivaliwe. Okanye inokudlulisela ii-elektroni ngqo kwioksijini, nto leyo ebuyisela imo eluhlaza okwesibhakabhaka ize yenze iperoksayidi yehayidrojeni. Ngenxa yokuba idayi ibuyiselwa kwimo yayo, isixa esincinane sinokuphinda lo mjikelo izihlandlo ezininzi, sisebenzisa ngokuthe ngcembe ii-ekwivalenti zokunciphisa yaye sisenza iperoksayidi ngokuqhubekayo.
Amanye amasebe amabini atshintsha ngokupheleleyo ikhemistri. Ubhedu okanye intsimbi ekhululekileyo iguqula loo peroksayidi ikwaziyo ukusasazeka ibe ziioksidanti zasekuhlaleni ezonakalisa ngakumbi, ngokusabela kohlobo lweFenton. Ukukhanya okubomvu kuvula isebe elahlukileyo le-photochemistry, apho idayi evuselelweyo idlulisela amandla kwioksijini ize yenze ioksijini ye-singlet, uhlobo oluchazwe ngokweenkcukacha kwingcaciso ye-photochemistry yohlobo I nohlobo II. Umjikelo weredoksi ebumnyameni, umonakalo owandiswa ziintsimbi, nomonakalo we-photodynamic ziindlela ezintathu ezahlukeneyo ezisuka kwimolekyuli enye.
Itheyibhile yeemeko neziphumo
Itheyibhile engezantsi sisixhobo sokugcina. Umqolo ngamnye ubonisa into enye eguqukayo, icala etyhalela kulo, novavanyo oluxhasa oko. Isiphumo esiluncedo sithetha umlinganiselo obonisa ukhuseleko okanye ukuphucuka. Isiphumo esibi sithetha ioksidanti engakumbi, ukuphela kwezibonelelo ngakumbi, okanye umonakalo ongakumbi.
| Imeko | Icala lesiphumo | Into eboniswe luvavanyo |
|---|---|---|
| Uxinano oluphantsi, 0.1 ukuya ku-1 uM, iimitokhondriya ezahluliweyo | Ukuphucuka kwemveliso yamandla kunye neperoksayidi ephezulu | I-0.1 uM iphucule ukusetyenziswa kweoksijini kwiimitokhondriya zentliziyo yeempuku eziphilileyo nezinesifo seswekile; i-100 nM ukuya ku-1 uM ibuyisele ngokuyinxenye i-ATP, umahluko wombane kwinwebu, nokufunxwa kwekhalsiyam kwiimitokhondriya zobuchopho ezivaliweyo, ngoxa ukukhutshwa kweperoksayidi kunyuke kuzo zonke iimeko |
| Uxinano oluphezulu, ngaphezu kwe-5 uM, iiseli ezivinjwe iglukhosi | Umqondiso ombi weeoksidanti | Iiseli ze-endothelium zenze ioksideshini kwisalathisi esibanzi se-ROS zaza zalahlekelwa yi-glutathione ekwimeko encitshisiweyo ngaphezu kwe-5 uM xa iglukhosi ingekho; ukongeza iglukhosi kuthintele zombini |
| Iisubstrate zekhompleksi I (iglutamate kunye nemalate) | Iperoksayidi engakumbi | Uphando lweemitokhondriya zobuchopho nolwentliziyo zombini zifumene ukwanda kokukhutshwa kweperoksayidi ngeesubstrate ezinxulumene ne-NADH |
| Isuccinate kunye nerotenone, iimitokhondriya zentliziyo, 0.1 uM | Iperoksayidi encinane kuloo nkqubo yovavanyo | Lo kuphela umlinganiselo weperoksayidi obonise ngokucacileyo isiphumo se-antioxidant kweli qela; qaphela ukuba inkqubo iquke irotenone yaza yasebenzisa izicubu ezahlukileyo, ngoko isubstrate yodwa ayisichazi esi siphumo |
| Ukukhanya okubomvu, 20 uM kunye ne-630 nm | Umonakalo ombi kwi-DNA | Akukho monakalo ubalulekileyo kwi-DNA yeemitokhondriya ebumnyameni kwi-20 uM; uxinano olufanayo kunye nokukhanya okubomvu lonakalise zonke iziqwenga ezivavanyiweyo |
| Uxinano oluphezulu kakhulu ebumnyameni, 100 uM | Umonakalo ombi okhethayo kwi-DNA | Umonakalo okhethayo kwi-DNA yeemitokhondriya kwiindawo zolandelelwano ezityebe ngeepurine, utshintsho olukhulu xa luthelekiswa nomqondiso weperoksayidi kuxinano lwenanomolar |
| Ubhedu okanye intsimbi kunye ne-NADH, i-DNA ngaphandle kweeseli | Umonakalo ombi obangelwa yioksideshini | Ubhedu lujolise umonakalo kulandelelwano lwe-p53 oludla ngokuchaphazeleka; i-iron EDTA ibangele umonakalo obanzi; i-catalase nezibopheleli zeentsimbi zithintele iindlela ezihambelana nazo; iguanine eneoksideshini inyukile |
| Iglukhosi ikhona, iiseli ezipheleleyo | Ukuthomalalisa okukhuselayo nangona umjikelo ukhawuleza | Iglukhosi inyuse ukuncitshiswa kwedayi kodwa yehlisa uxinzelelo olupheleleyo, nto leyo ehambelana nokunikezelwa kwe-NADPH yindlela ye-pentose phosphate ukuze ii-antioxidant ziphinde zisetyenziswe |
| Iiseli ezilayishwe nge-ascorbate | Okuxubeneyo: i-ascorbate isetyenzisiwe, umqondiso wesalathisi uthomalalisiwe | Idayi yenze ioksideshini ngokuthe ngcembe kwi-ascorbate engaphakathi kwiiseli naxa iglukhosi ikhona, ngoxa icinezela ngokuyinxenye ioksideshini yesalathisi; uvimba wokhuselo uhlawule loo ndleko |
| Izilwanyana ezilungiselelwe uvavanyo lwerotenone, idayi inikwe kuqala | Isiphumo esiluncedo kwizicubu | Ukunikwa kwedayi kwangaphambili kunciphise umonakalo kwi-DNA yeemitokhondriya obangelwa yirotenone kumbindi wobuchopho beempuku nangona inyusa iperoksayidi kwiimitokhondriya ezahluliweyo |
Eyona nto ibalulekileyo yipateni ebonakala kuyo yonke imiqolo. Ukuveliswa kweperoksayidi nokhuseleko lwebhayoloji ziinkalo ezahlukileyo. Ungenelelo lunokuba nesiphumo esibi kweyokuqala nesiluncedo kweyesibini ngaxeshanye.
Kutheni idosi enye inika iimpendulo ezahlukeneyo
Uxinano lumisela amandla okudlulisa ii-elektroni, kungekhona isiphumo sokugqibela. Ukukhutshwa kweperoksayidi kwiimitokhondriya zobuchopho kunyuke ngendlela enokulinganiswa ukusuka kwi-50 nM ukuya phezulu kuphando lweemitokhondriya zobuchopho ezipheleleyo, ngoxa umonakalo ocacileyo kwi-DNA yeemitokhondriya ubufuna i-100 uM ebumnyameni. Lowo ngumahluko omalunga namawaka amabini phakathi komqondiso wokuqala nokonakala kwemathiriyeli yemfuza, kodwa awungomda wokhuseleko. Izinto ezilinganisiweyo, amacandelo, namaxesha okuvezwa azifani, ngoko amanani abonisa iziganeko ezahlukileyo kunokuba abe ngamanqaku egophe elinye. Ingxoxo ngobudlelwane bedosi nesiphumo ibeka olu hlobo lomahluko phakathi komqondiso kwinqanaba eliphantsi nomonakalo kwinqanaba eliphezulu kumxholo obanzi we-hormesis.
Isubstrate igqiba apho ii-elektroni zingena khona. Izibaso ezinxulumene ne-NADH zinika idayi ii-ekwivalenti zokunciphisa ezininzi ukuze ixhase indlela eluncedo yokugqitha kumqobo kunye nokusabela kwioksijini okuchitha izibonelelo. Isishwankathelo esisoloko sicatshulwa sokuba isuccinate yenza idayi ibe yi-antioxidant ngoxa iglutamate iyenza ibe yi-pro-oxidant sitolika idatha ngaphezu koko ikubonisayo, kuba imeko yesuccinate yokulinganisa iperoksayidi kuphando lwentliziyo yayiquka nerotenone, kwaye yasebenzisa izicubu nedosi ezahlukileyo kwezo zophando lobuchopho olufumene ukunyuka kweperoksayidi kuzo zonke iisubstrate neemeko zokuphefumla.
Ukukhanya kutshintsha indlela yokusebenza, kungekhona ubukhulu besiphumo kuphela. Owona mahluko ucacileyo kweli qela kukuba i-20 uM ebumnyameni ayenzanga nto inokubonwa kwiziqwenga ze-DNA yeemitokhondriya, kodwa i-20 uM phantsi kokukhanya okubomvu yonakalise zonke. Nabani na othelekisa uvavanyo olukhanyisiweyo nolusebumnyameni uthelekisa i-photochemistry nomjikelo weredoksi.
Iintsimbi ziguqula ioksidanti. Ngaphandle kweentsimbi, umjikelo wedayi ebumnyameni wenza iperoksayidi, imolekyuli ekwaziyo ukusasazeka nesetyenziswa ziiseli njengomqondiso. Xa kukho ubhedu okanye intsimbi efikelelekayo, idayi encitshiswe yi-NADH inceda ukuncitshiswa kwentsimbi, ize intsimbi encitshisiweyo iguqule iperoksayidi ibe ziintlobo zehydroxyl okanye zeperoksayidi yobhedu ecaleni kwe-DNA. Yileyo indlela uphando olungenazo iiseli nge-NADH nee-ion zeentsimbi oluvelise ngayo umonakalo okhetha iindawo ezithile nomonakalo obanzi kwi-DNA, kusetyenziswa idayi enye yokuqala. Indlela icandelo elilawula ngayo iintsimbi, kungekhona idayi yodwa, igqiba ukuba eli sebe libalulekile na.
Imeko yezibaso igqiba ukuba iseli iyakwazi na ukuhlawula iindleko. Kwiiseli ze-endothelium ezivezwe kwidayi ye-2 ukuya ku-20 uM, ukususwa kweglukhosi kuveze iindleko zeeoksidanti ngoxa ukunikezelwa kweglukhosi kuzisusile, nangona iglukhosi ikwakhawulezise ukuncitshiswa kwedayi. Umjikelo okhawulezayo onokhuselo olunezibonelelo ubhetele kunomjikelo ocothayo onokhuselo olungenazibonelelo. Naliphi na ibango ngeeoksidanti elingayikhankanyiyo imeko yeglukhosi okanye ye-NADPH malithathwe njengelingaphelelanga.
Izicubu zigqiba izixhobo ezikhoyo. Iiseli ze-endothelium zibuyisela i-NADPH ngokucolwa kweglukhosi yaye zinemithombo yee-antioxidant kwi-cytosol. Iimitokhondriya ezahluliweyo azinayo nayiphi na kwezi. I-DNA ecociweyo ayinazo nezixhobo zokulungisa umonakalo. Isiphumo kwesinye isampulu asixeli kangako ngezinye, yiyo loo nto inqaku elicwangcisiweyo ngeempendulo ezikhethekileyo kwizicubu kuya kufuneka lizigcine zahlukene ezi nkqubo.
Umlinganiselo othe ngqo awululo ukhuselo olulandelayo
Imibhalo emininzi idibanisa amanqanaba amabini agcinwa ahlukene luvavanyo. Elinye inqanaba libuza ukuba ingakanani ioksidanti evelileyo. Elinye libuza ukuba iseli iphendule njani.
Iimvavanyo zeperoksayidi zohlobo lwe-Amplex zikufutshane kakhulu nenqanaba lokuqala, kodwa nazo zinika ingxelo yesixa sentsalela esihambayo, oko kukuthi imveliso kuthatyathwe ukutshatyalaliswa kuthatyathwe nokukhutshwa. Uphando lweemitokhondriya zobuchopho lufumene utshintsho kumacala omabini: kwenziwe iperoksayidi engakumbi yaye kususwe ngokucothayo isixa seperoksayidi esongezwe ngaxeshanye. Ezilandelayo ke yioksideshini ye-glutathione, ukusetyenziswa kwe-ascorbate, iguanine eneoksideshini, nomonakalo kwi-DNA othintela i-polymerase. Inyathelo ngalinye longeza iinkqubo zebhayoloji phakathi kweoksidanti nomlinganiselo ofundwayo.
Ii-enzayim ze-antioxidant eziqhutywa yi-Nrf2 nokwenziwa kweemitokhondriya ezintsha zikwinqanaba lesibini. Ziinkqubo zokuziqhelanisa ezinokuqaliswa kukunyuka okuncinane nokufutshane kweperoksayidi, yaye ababhali bophando lokhuselo lweemitokhondriya zobuchopho bacebisa kanye eso siqalisi soxinzelelo oluncinane ngoxa beqaphela ukuba ikhonkco lonobangela elihamba nge-Nrf2 lisekelwe kuphando lwangaphambili kunobungqina babo obupheleleyo. Ukhuselo olufika emva kweeyure ngeeproteni ezintsha aluthethi ukuba ikhemistri eluqalisileyo ibiyi-antioxidant. Luthetha ukuba isiganeko esincinane se-pro-oxidant sihlawule ukhuselo olukhulu. Izikhokelo zokufunda amabango anjalo, kuquka imida yeemvavanyo nomahluko phakathi kweesampulu, ngumxholo wesikhokelo sokufunda uphando nge-methylene blue.
Kutheni iimvavanyo zingavumelani
Isalathisi esibanzi esifana ne-dihydrofluorescein sinika ingxelo yeoksideshini ebanzi yesalathisi, kungekhona uxinano lweperoksayidi. Sixhomekeke kwikhemistri ye-peroxidase neheme kwaye sinokuphoswa kukunyuka kweperoksayidi okufunyanwa luvavanyo lwe-Amplex olulungelelanisiweyo. Uphando lweemitokhondriya zobuchopho lubone iperoksayidi ephezulu kakhulu ngaphandle komqondiso wesuperoksayidi ohambelana nayo, nto leyo esisilumkiso ngokucaphula naliphi na ibango elinye le-antioxidant elisekelwe kwidayi. Ukudibana kwemimandla yokufunxwa kokukhanya ngumbuzo ofanelekileyo wokuhlola, kuba idayi ifunxa ukukhanya okubonakalayo kufutshane nemimandla eqhelekileyo yokuvuselela neyokukhupha ukukhanya. Kodwa uphando olwenziwe ngenyameko lulungelelanise umlinganiselo neperoksayidi yesixa esaziwayo, lwanciphisa ukuvezwa kukukhanya okuvuselelayo kwaza kwatshintsha kancinci umqondiso, lwaza lwaqinisekisa ukususwa kweperoksayidi okucothayo nge-electrode eyahlukileyo. Ukuphazamiseka yinto efanele ukuvavanywa, kungekhona isizathu sokuyikhaba ngokuzenzekelayo.
Isiphumo sekhalsiyam sibonisa kwaloo mfuno yokuchaneka. Ukunikwa kwedayi ixesha elifutshane akuzange kutshintshe umthwalo opheleleyo wekhalsiyam ngaphambi kotshintsho lokuvumeleka kwenwebu kuphando lwentliziyo, kodwa kuphucule isantya sokufunxwa kwekhalsiyam kwiimitokhondriya zobuchopho ezivaliweyo kuphando lweemitokhondriya zentliziyo olugxile kwisifo seswekile. Izinto ezilinganisiweyo zahlukile, iinkqubo zahlukile, akukho kuphikisana.
Uluhlu lokuhlola ngaphambi kokuthemba isigqibo
Thatha sonke isigqibo se-antioxidant okanye se-pro-oxidant njengengxelo ephathelele inkqubo ethile, uze ubuze imibuzo emihlanu. Kuxinano olungakanani, yaye kweliphi icandelo. Ngowuphi umnikeli wee-elektroni yaye ngowuphi umamkeli okhuphisanayo. Ekukhanyeni okanye ebumnyameni, yaye kubude bamaza nedosi ezingakanani. Zeziphi iintsimbi ezifumanekayo, yaye yeyiphi imithombo yezibaso nee-antioxidant enezibonelelo. Kwaye ngoluphi uvavanyo, olulinganisa ukuhamba kweeoksidanti, umonakalo, okanye impendulo yokuziqhelanisa. Guqula nayiphi na impendulo enye, ibe kwaloo molekyuli inye inokushukuma kule theyibhile isuke ekukhuseleni iye ekonakaliseni ngaphandle kokuphikisana konke konke.