Wikamina A
E hoʻolauna pōkole
ʻO ka Vitamin A e komo pū ana me nā huaora A1 a me A2. ʻO nā huaora A1 a me A2 he like ke ʻano) Hiki ke hana ʻia ka Retinol mai ka beta-carotene i loaʻa mai nā mea kanu. Ma lalo o ke catalysis o β-carotene-15, 15'-peroxide (bioxygenase) i loko o ke kino, hiki ke hoʻololi ʻia ka β-carotene i ʻelua mau molekala o retinaldehyde (ratinal), a me retinaldehyde i reductase Ua hoʻemi ʻia i retinol ma lalo o ka hana a. No laila, ua ʻike ʻia hoʻi ka beta-carotene ʻo ia ka huaora A.
Nā waiwai kemika
He kristal ʻōniʻoniʻo melemele a pauka crystalline paha ka Vitamin A, ʻaʻole hiki ke hoʻoheheʻe ʻia i ka wai a me ka glycerine, a hiki ke hoʻoheheʻe ʻia i ka hapa nui o nā mea hoʻoheheʻe organik e like me nā alcohols, ethers, hydrocarbons a me nā hydrocarbons halogenated. ʻO ka inoa kemika o ke kino o ka vitamin A - retinol ʻo ia ka all-trance 3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclohexene-1)-2,4,6,8-nontetraene-1-ol, me 4 mau pilina pālua i hoʻohui ʻia ma kona kaulahao ʻaoʻao.
Nā hana a me nā hopena physiological
He wikamina momona-hoʻoheheʻe ʻia ka wikamina A, a ʻo kāna hana kino ma ke ʻano he waikawa retinoic. He kumu koʻikoʻi ʻo Carotene no ka wikamina A. ʻO ka wikamina A bioactive loa i loko o ka carotene ʻo ia ka beta-carotene. ʻO ka nui o ka omo ʻana i loko o ka ʻōpū o ke kanaka ma kahi o hoʻokahi hapaono o ka wikamina A. Mālama nui ʻia ka wikamina A i loko o ke kino, e helu ana no 90% a 95% o ka nui holoʻokoʻa, a mālama ʻia kahi liʻiliʻi i loko o ka ʻiʻo adipose. He kuleana koʻikoʻi ko ka wikamina A i ka hana metabolic o ke kino o ke kanaka.
