I-Vitamin A
Ngenisa kafushane
I-Vitamin A ihlanganisa amavithamini A1 no-A2. Amavithamini A1 no-A2 afana ngesakhiwo) I-Retinol ingakhiwa kusuka ku-beta-carotene etholakala ezitshalweni. Ngaphansi kwe-catalysis ye-β-carotene-15, 15'-peroxide (i-biooxygenase) emzimbeni, i-β-carotene ingaguqulwa ibe ama-molecule amabili e-retinaldehyde (i-ratinal), kanye ne-retinaldehyde ku-reductase. Yehliswa ibe yi-retinol ngaphansi kwesenzo se-. Ngakho-ke, i-beta-carotene yaziwa nangokuthi i-vitamin A.
Izakhiwo zamakhemikhali
I-Vitamin A iyi-crystal ephuzi noma i-crystalline powder, engancibiliki emanzini nase-glycerine, futhi incibilika ezinyibilikisini eziningi eziphilayo ezifana nama-alcohols, ama-ether, ama-hydrocarbon kanye nama-hydrocarbon ane-halogenated. Igama lamakhemikhali lomzimba we-vitamin A - i-retinol yi-all-trance 3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclohexene-1)-2,4,6,8-nontetraene-1-ol, enezibopho eziphindwe kabili ezine ezihlanganisiwe eketangeni layo eliseceleni.
Imisebenzi nemiphumela yemvelo
I-Vitamin A iyi-vitamin encibilika emafutheni, futhi umsebenzi wayo womzimba uvame ukuba ngesimo se-retinoic acid. I-Carotene iwumthombo obalulekile we-vitamin A. I-Vitamin A esebenzayo kakhulu ku-carotene yi-beta-carotene. Izinga lokumuncwa emathunjini omuntu licishe libe yingxenye yesithupha ye-vitamin A. I-Vitamin A igcinwa kakhulu esibindini emzimbeni, ihlanganisa cishe u-90% kuya ku-95% wenani eliphelele, kanti inani elincane ligcinwa ezicutshini zamafutha. I-Vitamin A idlala indima ebaluleke kakhulu emsebenzini womzimba womuntu.
