Isihloko
I-methylene blue njenge-antioxidant ne-pro-oxidant: yini eshintsha umphumela?
Ake sithi amalabhorethri amabili ahlola udayi ofanayo oluhlaza okwesibhakabhaka bese ebika imiphumela ephikisanayo. Kwelokuqala, ama-mitochondria ahlukaniswe namaseli obuchopho aphefumula kangcono futhi akhiqiza i-ATP eyengeziwe. Kwelesibili, lawo ma-mitochondria akhulula i-hydrogen peroxide eningi kakhulu. Yomibili imibiko ilungile. Ichaza umjikelezo ofanayo obonwa emaphethelweni amabili, futhi ukudideka kuqala lapho abafundi bethatha isiphetho esisodwa njengendaba yonke.
Iphutha liwukubuza ukuthi yiliphi igama elichaza le molekyuli. I-methylene blue iyisidlulisi sama-electron, njengoba ibalazwe lezindawo ezisebenza kuzo kubhayoloji yamaseli libonisa ngomongo obanzi. Udayi owenziwe i-oxidation wamukela ama-electron bese uba yi-leucoMB engenambala. I-leucoMB idlulisela lawo ma-electron phambili bese iphinde ibe luhlaza okwesibhakabhaka. Okubonayo kuncike ekutheni ubani onikela ngama-electron, ubani owamukelayo, nokuthi uhlelo luyakwazi yini ukususa i-hydrogen peroxide ekhiqizwa phakathi naleyo nqubo. Umbuzo ofanele awukona ukuthi udayi uyi-antioxidant yini. Uwukuthi izimo zivumela lesi sidlulisi ukuba senzeni.
Umjikelezo okhiqiza zombili izinhlangothi
Ebumnyameni, umjikelezo oyinhloko mfushane. I-NADH, i-NADPH, noma abathwali abasochungechungeni lokuphefumula banika udayi ama-electron, bawenze i-reduction. Udayi owenziwe i-reduction usuba nezindlela ezincintisanayo zokuwadlulisela. Ungadlulisela ama-electron ku-cytochrome c futhi usekele ukugeleza okudlula eceleni kwe-complex elimele; yingakho ukuphefumula kanye namandla kagesi olwelwesi kubuyela ngokwengxenye lapho i-complex I noma III ivinjiwe. Noma ungadlulisela ama-electron ngqo kumoya-mpilo, okubuyisela udayi esimweni esiluhlaza okwesibhakabhaka futhi kukhiqize i-hydrogen peroxide. Njengoba udayi uvuselelwa, inani elincane lingawuphinda lo mjikelezo izikhathi eziningi, lilokhu lisebenzisa ama-reducing equivalent futhi lilokhu likhiqiza i-peroxide.
Amanye amagatsha amabili ayishintsha ngokuphelele le nqubo yamakhemikhali. Ithusi noma insimbi engaboshiwe iguqula le peroxide ekwazi ukusabalala ibe ama-oxidant endawo abhubhisa kakhulu ngokusabela kohlobo lwe-Fenton. Ukukhanya okubomvu kuvula igatsha elihlukile lokusabela kwamakhemikhali okubangelwa ukukhanya, lapho udayi ovuswe amandla udlulisela amandla kumoya-mpilo futhi ukhiqize i-singlet oxygen, uhlobo oluchazwe ngokuningiliziwe encazelweni ye-photochemistry yohlobo I nohlobo II. Umjikelezo we-redox ebumnyameni, ukulimala okwandiswa izinsimbi, nokulimala okubangelwa ukukhanya kuyizindlela ezintathu ezihlukene ezimane ziqale ngemolekyuli eyodwa.
Ithebula elihlanganisa izimo nemiphumela
Ithebula elingezansi liyinsiza okufanele uyigcine. Umugqa ngamunye ubonisa isici esisodwa esiguqukayo, indlela esiqondisa ngayo umphumela, kanye nesilingo esisekela lokho. Okuhle kusho isilinganiso esibonisa ukuvikeleka noma ukuthuthuka. Okubi kusho ama-oxidant engeziwe, ukuphela okwengeziwe kwezinsiza, noma ukulimala okwengeziwe.
| Isimo | Ukuqondana komphumela | Okuboniswe yisilingo |
|---|---|---|
| Ukugxila okuphansi, 0.1 kuya ku-1 uM, ama-mitochondria ahlukanisiwe | Ukuthuthuka kwe-bioenergetics kanye ne-peroxide eyengeziwe | U-0.1 uM wathuthukisa ukusetshenziswa komoya-mpilo kuma-mitochondria enhliziyo yamagundane aphilile nanesifo sikashukela; u-100 nM kuya ku-1 uM wabuyisela ngokwengxenye i-ATP, amandla kagesi olwelwesi, kanye nokumuncwa kwe-calcium kuma-mitochondria obuchopho ayevinjiwe, kuyilapho ukukhululwa kwe-peroxide kwanda kuzo zonke izimo |
| Ukugxila okuphezulu, ngaphezu kuka-5 uM, amaseli ancishwe i-glucose | Isignali embi yama-oxidant | Amaseli e-endothelium enza i-oxidation kuphenyi olujwayelekile lwe-ROS futhi alahlekelwa yi-glutathione esesimweni se-reduction ngaphezu kuka-5 uM lapho i-glucose ingekho; ukwengeza i-glucose kwakuvimbela kokubili |
| Ama-substrate e-complex I (i-glutamate kanye ne-malate) | I-peroxide eyengeziwe | Ucwaningo lwama-mitochondria obuchopho nolwenhliziyo lwathola ukukhululwa kwe-peroxide okwandisiwe ngama-substrate axhumene ne-NADH |
| I-succinate kanye ne-rotenone, ama-mitochondria enhliziyo, 0.1 uM | I-peroxide encane kuleyo nqubo | Yisona kuphela isilinganiso se-peroxide kuleli qoqo esasibonisa ngokusobala umphumela we-antioxidant; qaphela ukuthi inqubo yayihlanganisa i-rotenone nezicubu ezihlukile, ngakho i-substrate yodwa ayiwuchazi lo mphumela |
| Ukukhanya okubomvu, 20 uM kanye no-630 nm | Ukulimala okubi kwe-DNA | Akubanga khona ukulimala okuphawulekayo kwe-DNA yama-mitochondria ebumnyameni ku-20 uM; ukugxila okufanayo nokukhanya okubomvu kwalimaza zonke izingcezu ezahlolwa |
| Ukugxila okuphezulu kakhulu ebumnyameni, 100 uM | Ukulimala okubi kwe-DNA okukhethiwe | Ukulimala okukhethiwe kwe-DNA yama-mitochondria ezilandelaneni ezinama-purine amaningi, okuwushintsho olukhulu kusignali ye-peroxide esezingeni lama-nanomolar |
| Ithusi noma insimbi kanye ne-NADH, i-DNA engenamaseli | Ukulimala okubi okubangelwa i-oxidation | Ithusi laqondisa ukulimala esilandelaneni se-p53 esivame ukuba nezinguquko; i-iron EDTA yabangela ukulimala okubanzi; i-catalase nezinto ezibopha izinsimbi zavimba izindlela ezihambisana nakho ngakunye; i-guanine eyenziwe i-oxidation yanda |
| I-glucose ikhona, amaseli angahlukanisiwe | Ukuncishiswa komthelela okuvikelayo naphezu komjikelezo osheshayo | I-glucose yandisa ukwenziwa kwe-reduction kudayi kodwa yehlisa ukucindezeleka okuphelele, okuhambisana nokunikezwa kwe-NADPH yindlela ye-pentose phosphate ukuze kuvuselelwe ama-antioxidant |
| Amaseli agcwaliswe nge-ascorbate | Okuxubile: i-ascorbate yasetshenziswa, isignali yophenyi yancishiswa | Udayi waqhubeka nokwenza i-oxidation ku-ascorbate engaphakathi kwamaseli ngisho nalapho i-glucose ikhona, kuyilapho unciphisa ngokwengxenye i-oxidation yophenyi; inqolobane yezivikeli yathwala izindleko |
| Izilwane ezelashwa kusengaphambili ngaphambi kokuthola i-rotenone, udayi unikezwe kuqala | Umphumela omuhle ezicutshini | Ukwelashwa kusengaphambili ngodayi kwanciphisa ukulimala kwe-DNA yama-mitochondria okubangelwa i-rotenone ebuchosheni obuphakathi bamagundane, naphezu kokwandisa i-peroxide kuma-mitochondria ahlukanisiwe |
Okubalulekile yiphethini kuyo yonke imigqa. Ukukhiqizwa kwe-peroxide nokuvikeleka ngokwebhayoloji kuyizici ezihlukene. Ukwelashwa kungaba nomphumela omubi kwesokuqala futhi kube nomuhle kwesibili ngesikhathi esifanayo.
Kungani umthamo ofanayo unikeza izimpendulo ezihlukene
Ukugxila kunquma amandla okudlulisa ama-electron, hhayi isiphetho. Ukukhululwa kwe-peroxide kuma-mitochondria obuchopho kwanda ngezinga elikwazi ukutholwa kusukela ku-50 nM kuya phezulu ocwaningweni lwama-mitochondria obuchopho angonakalisiwe, kuyilapho ukulimala okusobala kwe-DNA yama-mitochondria kwakudinga u-100 uM ebumnyameni. Lokho kuyigebe elicishe libe yizikhathi eziyizinkulungwane ezimbili phakathi kwesignali yokuqala nokulimala kofuzo, kodwa akuwona umkhawulo wokuphepha. Izilinganiso zemiphumela, izingxenye zamaseli, nezikhathi zokuchayeka ziyahluka, ngakho izinombolo zikhomba izenzakalo ezihlukene kunokuba zibe amaphuzu ejikeni elilodwa. Ingxoxo yokusabela emthamo ibeka lolu hlobo lwegebe phakathi kwesignali ephansi nokulimala okuphezulu emongweni obanzi we-hormesis.
I-substrate inquma ukuthi ama-electron angena kuphi. Izibaseli ezixhumene ne-NADH zinikeza udayi ama-reducing equivalent amaningi kokubili endleleni ewusizo yokudlula eceleni nasokusabeleni okumoshayo nomoya-mpilo. Isifinyezo esivame ukucashunwa sokuthi i-succinate yenza udayi ube yi-antioxidant kanti i-glutamate iwenza ube yi-pro-oxidant sifinyelela ngaphezu kwalokho okusekelwa idatha, ngoba isimo se-succinate sokulinganisa i-peroxide ocwaningweni lwenhliziyo sasine-rotenone futhi sasebenzisa izicubu nomthamo okuhlukile kunocwaningo lobuchopho olwathola i-peroxide eyandisiwe ngaphansi kwazo zonke izimo ze-substrate nokuphefumula.
Ukukhanya kushintsha indlela yokusebenza, hhayi nje ubukhulu bomphumela. Umehluko ocace kakhulu kuleli qoqo ngu-20 uM ebumnyameni ongenzanga lutho olutholakalayo ezingcezwini ze-DNA yama-mitochondria, kanye no-20 uM ngaphansi kokukhanya okubomvu ozilimaze zonke. Noma ubani oqhathanisa isilingo esinokukhanya nesisebumnyameni uqhathanisa i-photochemistry nomjikelezo we-redox.
Izinsimbi ziguqula i-oxidant. Ngaphandle kwezinsimbi, umjikelezo wodayi ebumnyameni ukhiqiza i-peroxide, imolekyuli ekwazi ukusabalala amaseli ayisebenzisa futhi njengesignali. Uma kukhona ithusi noma insimbi etholakalayo, udayi owenziwe i-reduction yi-NADH usekela ukwenziwa kwe-reduction ensimbini, bese insimbi ekuleso simo ivuselela i-peroxide ibe izinhlobo zama-hydroxyl noma ze-copper peroxide eduze kwe-DNA. Yileyo ndlela ucwaningo olungenamaseli olusebenzisa i-NADH nama-ion ezinsimbi olwakhiqiza ngayo ukulimala kwe-DNA okukhetha izindawo ezivame ukuba nezinguquko kanye nokulimala okubanzi, luqala ngodayi ofanayo. Ukuphathwa kwezinsimbi kuleyo ngxenye yeseli, hhayi udayi wodwa, kunquma ukuthi leli gatsha libalulekile yini.
Isimo sokutholakala kwezibaseli sinquma ukuthi iseli lingakwazi yini ukuthwala izindleko. Emaseleni e-endothelium achayekiswe kudayi ongu-2 kuya ku-20 uM, ukususa i-glucose kwaveza izindleko zama-oxidant, kuyilapho ukunikeza i-glucose kuzisusa, nakuba i-glucose futhi yayisheshisa ukwenziwa kwe-reduction kudayi. Umjikelezo osheshayo onezivikelo ezinezinsiza ungcono kunomjikelezo onensayo onezivikelo ezingenazinsiza. Thatha noma yisiphi isimangalo ngama-oxidant esingasho isimo se-glucose noma se-NADPH njengesingaphelele.
Izicubu zinquma amathuluzi akhona. Amaseli e-endothelium avuselela i-NADPH ngokugaywa kwe-glucose futhi anezinqolobane zama-antioxidant ku-cytosol. Ama-mitochondria ahlukanisiwe awanakho lokho. I-DNA ehlanzisiwe ayinakho ngisho nokuzilungisa. Umphumela esimisweni esisodwa sokuhlola awubikezeli okuningi ngezinye, yingakho indatshana ehlelelwe ukusabela okuqondene nezicubu kuzodingeka ihlukanise lezi zimiso.
Ukulinganisa ngokuqondile akufani nezivikelo ezilandela kamuva
Imibhalo eminingi ihlanganisa amazinga amabili izilingo eziwahlukanisayo. Elinye izinga libuza ukuthi kwavela i-oxidant engakanani. Elinye libuza ukuthi iseli lasabela kanjani.
Ukuhlolwa kwe-peroxide kohlobo lwe-Amplex kuseduze kakhulu nezinga lokuqala, futhi ngisho nakho kubika ukugeleza okuphelele, okusho ukukhiqizwa kususwe ukubhujiswa kususwe ukukhishwa ngaphandle. Ucwaningo lwama-mitochondria obuchopho lwathola ukushintsha nhlangothi zombili: kwakheka i-peroxide eyengeziwe futhi kwasulwa kancane inani le-peroxide elengezwe ngesikhathi esisodwa. Ezigabeni ezilandela kamuva kukhona i-oxidation ye-glutathione, ukusetshenziswa kwe-ascorbate, i-guanine eyenziwe i-oxidation, kanye nokulimala kwe-DNA okuvimba i-polymerase. Isinyathelo ngasinye sengeza izinqubo zebhayoloji phakathi kwe-oxidant nomphumela olinganisiwe.
Ama-enzyme e-antioxidant aqhutshwa yi-Nrf2 nokwakheka kwama-mitochondria amasha kusezingeni lesibili. Kuyizinhlelo zokuzivumelanisa ezingaqalwa ukukhuphuka okuncane kwe-peroxide kwesikhashana, futhi ababhali bocwaningo lokuvikeleka kwama-mitochondria obuchopho baphakamisa sona kanye leso siqalisi sokucindezeleka okuncane, kuyilapho bephawula ukuthi uchungechunge lwembangela oludlula ku-Nrf2 lusekelwe emsebenzini wangaphambilini kunokuba lube sekuboniseni kwabo okuphelele. Ukuvikeleka okuvela emahoreni kamuva ngamaprotheni amasha akusho ukuthi ukusabela kwamakhemikhali okuqale inqubo kwakungokwe-antioxidant. Kusho ukuthi isenzakalo esincane se-pro-oxidant sithenge isivikelo esikhulu. Izixwayiso zokufunda izimangalo ezinjalo, kuhlanganise nemikhawulo yokuhlolwa nomehluko phakathi kwezinto ezilungiselelwe ukuhlolwa, ziyisihloko somhlahlandlela wokufunda ucwaningo lwe-methylene blue.
Kungani izindlela zokuhlola zingavumelani
Uphenyi olujwayelekile njenge-dihydrofluorescein lubika i-oxidation ebanzi yophenyi, hhayi ukugxila kwe-peroxide. Luncike ekusabeleni kwamakhemikhali kwe-peroxidase ne-heme futhi lungaphuthelwa ukwanda kwe-peroxide okutholwa ukuhlolwa kwe-Amplex okulinganiswe kahle. Ucwaningo lwama-mitochondria obuchopho lwabona i-peroxide ephakeme kakhulu ngaphandle kwesignali ye-superoxide ehambisana nayo, okuyisixwayiso sokungacaphuni noma yisiphi isimangalo se-antioxidant esisekelwe kudayi oyedwa kuphela. Ukugqagqana ekukhanyeni kuwumbuzo ofanele wokuhlola ukuqinisekisa ukunemba, ngoba udayi umunca ukukhanya okubonakalayo eduze kwamabhendi ajwayelekile okuvusa nokukhipha ukukhanya. Kodwa ucwaningo olucophelelayo lwalulinganise ukuhlolwa nge-peroxide yenani elaziwayo, lwanciphisa ukuchayeka ekukhanyeni okuvusa isignali kwaba noshintsho oluncane esignalini, futhi lwaqinisekisa ukususwa kwe-peroxide okunensayo nge-electrode ehlukile. Ukuphazamiseka kuyinto okufanele ihlolwe, hhayi isizathu sokwenqaba umphumela ngokuzenzakalela.
Umphumela we-calcium ubonisa isidingo esifanayo sokunemba. Udayi onikezwe isikhathi esifushane awushintshanga inani eliphelele le-calcium ngaphambi kokuguquka kokudluliseka kolwelwesi ocwaningweni lwenhliziyo, kodwa wathuthukisa isivinini sokumuncwa kwe-calcium kuma-mitochondria obuchopho ayevinjiwe, njengoba kuxoxwa ocwaningweni lwama-mitochondria enhliziyo olwalugxile esifweni sikashukela. Izilinganiso zemiphumela zihlukile, izimiso zihlukile, akukho ukuphikisana.
Uhlu lokuhlola ngaphambi kokwethemba isiphetho
Thatha sonke isiphetho sokuthi into iyi-antioxidant noma iyi-pro-oxidant njengombiko ngesimiso esithile, bese ubuza imibuzo emihlanu. Kukuphi ukugxila, futhi kukuyiphi ingxenye yeseli. Kusetshenziswa muphi umnikeli wama-electron futhi muphi umamukeli oncintisanayo. Kukhanya noma kumnyama, futhi kubuphi ubude begagasi nomthamo. Yiziphi izinsimbi ezitholakalayo, futhi yiziphi izinqolobane zezibaseli nama-antioxidant ezinezinsiza. Futhi kusetshenziswa kuphi ukuhlolwa, okukala ukugeleza kwama-oxidant, ukulimala, noma ukusabela kokuzivumelanisa. Shintsha noma iyiphi impendulo eyodwa, futhi imolekyuli efanayo ingasuka endaweni evikelayo iye kwelimazayo kuleli thebula ngaphandle kwanoma yikuphi ukuphikisana.