VITAMIN TAN TRONG NCVitamin l nhng cht hu c c trng lng phn t b, c cu to ho hc rt khc nhau v u c hot tnh sinh hc nhm m bo cho cc qu trnh ho sinh v sinh l trong c th tin hnh c bnh thng, v do , c nh hng rt ln i vi s trao i cht. Vitamin khng c tng hp ng vt bc cao, v vy chng phi c tip nhn cng vi thc n. Nhiu vitamin l tin cht ca cofactor (vitamin nhm B) tham gia vo cc phn ng enzyme, trong khi nhng vitamin khc tham gia vo qu trnh nhn v iu khin s sao chp (vitamin A), cc phn ng kh (vitamin C v E), to xng (vitamin D), ng mu (vitamin K) v.v... Nhm vitamin ha tan trong nc bao gm cc loi Vitamin nhm B v C. Chng ta s tm hiu v cu to ha hc,tnh cht, vai tr sinh hc v nhu cu ca c th v nhm vitamin ha tan trong nc.

1. Vitamin B, (Tia min, areorin, vitamin chng vim thn kinh)* Cu to ho hc Nm 1912 nh bc hc Ba Lan Funk phn lp t cm cht c kh nng cha vim thn kinh. Nm 1937 Uy-liam xc nh cu trc cht ny, cu trc gm 2 phn: vng pyrimidin v vng tiazol.

Vitamin B1 [(2- metyl, 6-aminopyndin, 5-(4- metyl, 5-oxyetyl tiazolorid hydroclond)] *Tnh cht:

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- B1 bn trong mi trng axit, khng bn trong mi trng kim, pH kim B1 b ph hy nhanh chng khi un nng. -B1 dng tinh th v ha tan tt trong nc; chu c qu trnh gia nhit thng thng -Khi oxi ha B1 chuyn thnh hp cht Thiocrom pht hunh quang, tnh cht ny c ng dng tnh nh lng vitamin B1. * Tc ng sinh hc: Vitamin B1 ng vai tr quan trng trong trao i vt cht c bit l chuyn ho glucid v trong hot ng thn kinh (gii thch c ch ph thng v vim thn kinh - phn trc). - Vitamin B1 tham gia vo nhm ghp ca enzym kh carboxyl, tc l decarboxylase. Loi phn ng kh carboxyl ca ceto acid tin hnh theo 2 kiu vi s tham gia ca 2 loi enzym khc nhau: + Phn ng kh carboxyl khng km oxy ho thng gp vi sinh vt, nh t bo men ru, nhm ghp enzym ny l dn xut tiaminpirophotphat (TPP).

+ m bo ng vt, s kh carboxyl tin hnh theo kiu oxy ha. Enzym xc tc c nhm ghp l hp cht gia TPP v acid hpoic, gi l lipotiaminpirophotphat (LTPP).

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im hot ng ca hai nhm ghp trn u l nhm SH, nhm ny c kh nng dng vng khi mt H hoc dng tim (SH) khi c H, l nguyn nhn v kh nng oxy - ho hon nguyn.

Khi thiu vitamin B1 enzym decarboxylase khng hnh thnh c nn qu trnh kh carboxyl ca acid pyruvic (xetoacid) b ngng tr v ng ng cc m bc. * Nhu cu v ngun vitamin B1 Vitamin B1 ph bin thc vt, nm enzym, c bit l vi sinh vt k sinh trong ng tiu ho c kh nng tng hp vitamin B1. ng vt nhai li (tru, b, d,cu) nh c s hot ng ca vi sinh vt d c nn khng b thiu vitamin B1 Hm lng trung bnh ca vitamin ny trong mu ngi l t 2 - 8 mg%. Nhu cu vitamin B1 khc nhau ph thuc vo yu t sinh l, lao ng, nhu cu sn xut Vitamin B1 c nhiu trong cm go, gan, thn ... mm ng cc v nm men l ngun rt giu vitamin ny. Lng tip nhn hng ngy i vi ngi l 1-1,5 mg. Thiu vitamin ny nh hng n qu trnh trao i carbohydrate dn n bnh ph thng, hay cn gi l bnh beri-beri, ri lon thn kinh v nh hng n chc nng ca tim. B1 ch bn vi nhit trong mi trng acid, cn trong mi trng kim n b phn hu nhanh chng khi un nng. Khi oxy ho B1 chuyn thnh mt hp cht gi l thiocrome pht hunh quang.Tnh cht ny c s dng nh lng vitamin B1. Hm lng B1 trong nguyn liu c th thay i ng k tu thuc iu kin bo qun v ch bin. V d: go xt k hm lng B1 c th b gim n 4

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ln so vi ban u. m khi bo qun nguyn liu (thc, go) cng cao, hm lng vitamin B1 b gim cng mnh.

2. Vitamin B2 (Ribonavin)Trc kia c gi l lactoflavin v ln u tin c tch ra t sa. Bn cnh nicotinamid-nucleotide NAD+ v NADP+ flavin-nucleotide: flavin-adenindinucleotide (FAD) v flavin-mononucleotide (FMN) l nhng nhm vn chuyn hydro quan trng. Chng tham gia hn 100 phn ng oxy ho kh. V d, qu trnh kh carboxyl ho bng cch oxiho pyruvic acid, oxy ho acid bo, kh amin ho bng cch oxiho amino acid... Coenzyme ny c to nn t vitamin riboflavin bng phosphoryl ho (FMN) v tip theo adenyl ho (FAD). * Cu to ho hc Cu trc ca vitamin B2 c Cun v Ca re tm ra v tng hp (1934). Phn t cha dn xut ca ng ribose (ribitil).

*Tnh cht: L tinh th mu vng, c v ng, tan trong nc, tan trong ru, khng tan trong cc dung mi ca cht bo. - B2 tng i bn vi nhit v axit. - B2 nhy cm vi nh sng. - Di tc dng ca tia cc tm v mi trng kim, B2 bin thnh Lumiflavin. - Di tc dng ca tia cc tm v mi trng axit, B 2 bin thnh Lumicrom l cht c hunh quang mu lam. - Trong c th B2 d b photphoryl ha nn nhm hot ng (nhm ngoi) ca enzym xc tc qu trnh oxy ha kh, thng gp l Riboflavin mononucleoit (FMN); hay Riboflavin adenin dinucleotit (FAD), khi kt hp vi protein, to nn cc dng enzym dehydrogenaza. * Tc ng sinh hc:

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+ Tham gia vo cu trc ca enzym dehydrogenase hiu kh (men vng) dng FAD v FMN. Trong c th ng vt gn 97% riboflavin trng thi lin kt vi protein enzym, cn gn 3% trng thi t do. Riboflavin ca thc n a vo s c phosphoryl ho bi ATP vch rut v gan thnh 2 dng flavinmononucleotid (FMN) v flavin adenozindinucleotid (FAD). Hai dn xut ny chnh l nhm ghp ca lp enzym h hp - lp men vng flavoprotein, loi enzym ny thc hin phn ng oxy ho hon nguyn tc l chuyn vn hydrogen trong qu trnh h hp m bo. Khi thiu vitamin B2 th s tng hp enzym vng nh tr gy ri lon trao i vt cht, lm qu trnh h hp m bo khng thc hin y . + vitamin B2 c lin quan vi cc vitamin khc. Khi thiu vitamin B1 th nhu cu riboflavin tng ln, thiu riboflavin kh nng t cung cp vitamin C gim... *Chc nng ho sinh Chc nng oxy ho kh ca FMN v FAD l do vng isoalloxazin chu trch nhim. mt phn ng kh hon ton hai in t v hai proton c tip nhn. Dng oxy ho hon ton ca riboflavin l nhng tinh th vng da cam, hp th bc sng 370 v 450 nm. Dng kh ca n khng mu v mt tnh hp th 450 nm. Cc coenzyme flavin nucleotide dng kh cng c th b oxy ho tr li khi c cc cht nhn in t nh xanh methylen, 2,6diclorophenolindophenol FADH2 + xanh methylen FAD + xanh methylen (dng oxy ho mu xanh) (dng kh khng mu) C th s dng cc tnh cht trn theo di cc phn ng do flavin dehydrogenase xc tc. * Nhu cu v ngun vitamin B2 vitamin B2 c nhiu gan, tht, trng, sa, enzym bia kh, c chua, ng, u c Cc ng vt nh ln, g, ch v ngi thng xuyn rt cn vitamin B2 trong thc n. Tru, b, d, cu (ng vt nhai li) t i hi hn v vi khun ng tiu ha c kh nng tng hp c vitamin ny.

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Ln con cn 3mglkg thc n kh. Ngi cn 2 - 4mg/ngy.

3. Acid pantotenic (vitamin B3)* Cu to ho hc Vtamin B3 rt ph bin cc i tng sinh vt khc nhau, do c tn l acid pantotenic (theo ting La tinh pantothen l khp ni). N bao gm hai thnh phn l acid pantoic v -alanin: *Tnh cht: L cht lng nht, mu vng, tan trong nc v ru, bn vi nhit v oxy trong dung dch - B3 b phn hy trong dung dch axit hay baz. * Tc ng sinh hc v ngun gc: Vitamin B3 l tin cht ca coenzym A (vit tt COA).Thiu vitamin B3 nh hng chc nng thng thn b hoi t, xut huyt v thng thn, rng lng, rng tc, bc tc,vim da, thoi ha ty,. Vitamin B3 thng c nhiu trong nm enzym, gan, cc sn phm xanh ca thc vt v c tng hp bi cc vi khun ng rut. *Nhu cu : Cn 10 15mg/ngy. 4. Vitamin PP (Nicotinamid, nia xin, vitamin B5 - vitamin chng da kh) * Cu to ho hc Khi oxy ho nicotin thuc l bng acid cromic, ta thu c acid nicotinic. Trong cy ci thng c sn acid ny, khi vo c th ng vt acid nicotinic chuyn sang dng amid, tc l thnh vitamin PP, cng thc nh sau:

Trong m bo nhiu loi ng vt, vi sinh vt (cng nh thc vt) acid nicotinic c tng hp t tryptophan nh xc tc ca h thng nhiu enzym. Trong c nhm ghp l dn xut ca vitamin B2' B6' 6

*Tnh cht:

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Vitamin PP dng axit nicotic l tinh th hnh kim trng, c v axit, ho tan trong nc, trong ru, bn vi nhit, vi axit v kim. Dng amit cng l tinh th hnh kim trng, c v ng, tan tt trong nc, nhng km bn vi axit v kim hn so vi dng axit nicotic. Nhn chung PP khng b bin i khi nu nng thng thng. * Tc ng sinh hc Tham gia cu to NAD v NADP trong m bo sinh vt, vitamin PP c di dng t do v hp cht protein - enzym. l NAD (nicotiamid adenozin dinuleotid) v NADP (nicotinamid adenozin dinucleotid photphat). Hai cht ny l nhm ghp ca enzym oxy ho hon nguyn, tc l enzym dehydrogenase ym kh. Thiu vitamin PP ng vt thng mc bnh vim trc da sn si. Trong chn nui nu ch cho ln n ng ko di cng thng xy ra bnh ny v thiu tryptophan. Trong ng cn c cht khng vitamin PP - l acid pyndin - 3 - sulforic. Nu un si th khng vitamin PP ca ng s mt i. * Nhu cu v ngun vitamm PP Vitamin PP c nhiu gan, tht, sa b, trng, go, cm khoai ty, c rt... Nhu cu thay i tu theo thnh phn thc n Ngi cn 15 - 25mg/ngy Ch cn 0,25mg/1kg th trng Nga 0,l0mg/kg th trng Ln con cn 15 - 17mg/1kg thc n kh 5. Vitamin B6 (Pyridoxin, adennin) * Cu to ho hc: Pyndoxin, pyridoxamin v pyndoxal u c hot lc vitamin nn ghp thnh nhm vitamin B6

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*Tnh cht: L tinh th khng mu, v hi ng, ha tan tt trong nc v ru. - Bn khi un si trong axit hay kim. - Khng bn vi cht oxy ha. - B6 nhy cm vi nh sng. Chng phn hy nhanh khi chiu sng ni trng kim hay trung tnh, cn trong mi trng axit (HCl, O, 1N) th piridoxin, piridoxal bn hn piridoxamin. - Trong t nhin tn ti ngoi 3 dng trn cn c cc dng c gc photphat nh piridoxal photphat v pyridoxamin photphat, cc dng ny c hot tnh vitamin mnh v tham gia vo cu to nhiu enzym quan trng. * Tc ng sinh hc: Trong c th ng vt ( thn, gan, rut non) pyridoxin b oxy .ho thnh pyridoxal v cht ny li c phosphoryl-ho thnh pyridoxal photphat - y l nhm ghp ca loi enzym trao i. Vitamin B6 c tc dng quan trng i vi s chuyn ho protein (phn ng chuyn quan v kh carboxyl). Thiu vitamin B6 gia sc c nhng triu chng ri lon thn kinh, co git tng cn nh ng kinh. Vitamin B6 cn nh hng ti s tng hp ni tit t tuyn yn v bung trng (nhm oestrogen) nn khi thiu n qu trnh thai nghn b tr ngi. * Nhu cu v ngun vitamin B6 Vitamin B6 c tht, gan, enzym bia, bp ci, c rt, trng... Loi nhai li khng cn vitamin B6 thc n, v vi sinh vt d c tng hp c, cc loi ng vt khc cn cung cp pyridoxin u n. Ln con cn 0,5 - 1mg/1kg thc n kh G con cn 3 - 5 mg/1kg khu phn G mi cn t hn 1 - 2 mg. 6. Inozit - vitamin B7 * Cu to ho hc:

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*Tnh cht: Vitamin khng mu c tnh kim, d tan trong nc, ru, khng tan trong ete, bn trong axit, d phn hy trong kim. * Tc ng sinh hc: Inozit trong c th ng vt c 2 dng: + Dng lin kt inozit - photphatit ca no v dy thn kinh + Dng t do c trong cc m, nht l gan, dch sinh dc. Trong tinh dch ln, inozit n nh p sut thm thu do tinh trng tn ti lu c. i vi gan vitamin ny gip qu trnh tiu ha lipid d dng, thiu inozit ng vt chm ln, mc lng km, gan nhim thm lipid. * Nhu cu v ngun vitamin Inozit c tng hp cy ci, nht l trc thi k kt qu. Nhu cu cha c xc nh 7. Vitamin H (Biotin, vitamin B8) * Cu to ho hc: Biotin c th coi l hp cht ca vng tiopen v ur di dng vng v mch nhnh l acid valerianc.

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*Tnh cht: L tin th hnh kim khng mu tan tt trong nc, tan t trong ru khng tan trong dung mi hu c. - Bn vi oxy v H2SO4. - Phn hy bi H2O2, HCl, Naoh, nc Brom. - Vitamin H t b thay i khi bo qun. * Tc ng sinh hc + Tham gia mt s qu trnh sinh ho hc c th nh tng hp acid aspartic, qu trnh kh quan, kh carboxyl... + Triu chng thiu thon l bnh vim da ni mn (lc c, lc ln), lng tung, xng cong queo g. * Nhu cu v ngun vitamm Biotin c tng hp trong cy c, nht l l cy. C nhiu trong gan ng vt c sng, sa, nm men, u nnh, thn, tim, lng trng, Nhu cu thp: g con 2,5 /ngy; ngi cn 9 /ngy 8. Acid folic (vitamin Bc) * Cu to ho hc: Aci folic mang tn l vitamin Bc (c l ch vit tt ca t ting Anh chicken c ngh l g con) n n cng cn thit cho s pht trin ca g con. Acid fohc bao gm ba gc lin kt vi nhau l gc pterin, gc acid paraaminobenzoic v gc acid glutamic:

* Tc ng sinh hc Thiu vitamin Bc cng s b thiu mu. T acid folic d dng chuyn thnh acid tetrahydrofolic (COF, FH4) l coenzym ca cc enzym xc tc cho phn ng chuyn cc nhm cha mt carbon (nhng khng phi l CO2) 9. Vitamin B12 (xyancobalamin, vitamin chng thiu mu c tnh) 11

* Cu to ho hc Phn ch yu l vng porfin, trong vng pht A gn vi nguyn t co ban bng dy ni ng ho tr , ho tr cn li ca coban dng lin kt vi nhm CN phn th hai ca vitamin l nhn nucleotit ni vi vng Phi D ca porfmn. *Tnh cht: - Vitamin B12 dng tinh th, mu (do c Coban 45%) khng c v v mi. Nhit nng chy l 3000C. - Ha tan tt trong nc v ru. - Trong dung dch pH axit, hay trung tnh B12 bn trong ti nhit thng. - Ngoi nh sng B12 d phn hy. * Tc ng sinh hc Triu chng thiu vitamin B12 l s thiu mu c tnh trong tu xng v mu xut hin nhiu hng cu non v qu trnh to huyt b ngng tr. Mu b v nhiu hng cu, lng hemoglobin gim st. S h hp m bo cng b yu, s chuyn ho glucid v lipid b ri lon km theo nhng hin tng thn kinh suy nhc. * Nhu cu v ngun vitamin B12 Phn ln cc loi vi khun c kh nng tng hp vitamin B12 nu c nguyn t coban. Cc vi sinh vt d c, manh trng v rut gi u c kh nng tng hp vitamin B12 Khi cho loi nhai li y co ban th chng hon ton t tc ngun vitamin ny. Thc vt hon ton khng cha vitamin ny, rong ru bin s d cha vitamin B12 v c vi sinh vt k sinh hot ng. Vitamin Bi2 c trong tht, no, thn, gan, mu, sa, trng c. G con nui hon ton bng thc n thc vt cn 6 /1kg thc n; g ln cn 2 - 3 /1kg thc n; Ln con cn 22 /1kg thc n. Trong c th ng vt ni d tr B12 l gan 30 - 70%.

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10. Vitamin C (Acid ascorbic) * Cu to ho hc:

Acid ascorbic c kh nng hon nguyn cc cht, bn thn b oxy ho sang dng acid dchydroascorbic khng c hot tnh vitamin. Do c im ny nn vic bo qun vitamin C rt kh. 13

Trong c th thng gp 2 trng thi ascothic t do v lin kt.

*Tnh cht: L mt cht c v chua, khng mi, tinh th trng, tan trong nc, bn trong mi trng trung tnh v axit, khng bn trong kim. - Chu c nhit 1000C pH trung tnh hay axit. - D b oxy ha bi oxy khng kh, khi c mt ca Fe,Cu.. s tng nhanh s oxy - ha. S oxy ha cng xy ra khi c enzim oxy ha vitamin C ( thc vt). - Vitamin C tn ti, v chuyn ha thun nghch 2 dng oxy ha v kh * Tc ng sinh hc: Ngi v ng vt nu lu khng c n rau v hoa qu ti s b mc bnh scorbut. Triu chng in hnh ca bnh ny l hin tng hoi huyt qun, gy chy mu nim mc li, da, trong bp tht v.v... Rng b yu, lung lay d rng, xng gin v d gy. Ngoi ra cn nhng bin chng ng tiu ho (gim dch v v acid), tim v nhiu ri lon trong chuyn ho ng lipid, protein ca c th. + Vai tr sinh ho hc ch yu ca acid ascorbic l s tham gia qu trnh oxy ho hon nguyn, ngi ta tn thy hai loi enzym: ascorbin - reductase v ascorbin - oxvdase tham gia qu trnh oxy ho - hon nguyn cht glutation (C10H17N3SO6).

+ Acid ascorbic xc tc s vn chuyn hydrogen gia NAD.H2 hoc FAD.H2 vi h thng cytocrom. + Acid ascothic c tc dng kch thch hot ng ca enzym aconitase trong chu trnh Krebs, do n gin tip nh hng ti s chuyn ho glucose: Thiu vitamin C s tng hp v tch lu glycogen gan v c gim. st rt r, lc ny ta thy enzym hexokinase hot ng rt yu. +Vitamin C c lin quan cht ch i vi s trao i protein, c bit l protein ca cc m chng nh gn, xng... s c mt ca vitamin C cn thit cho s hnh thnh colagen - protein c s ca m lin kt, t procolagen, thiu vitamin C s lng colagen gim qu 2 ln so vi mc bnh

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thng Do vitamin C nh hng ti qu trnh lnh vt thng v gi bn thnh mch. + vitamin C cn nh hng n s hot ng sn sinh adrenalin ca tuyn thng thn hoc adrenocorticotropin ca tuyn yn. N c tc dng gi cho adrenalin khi b oxy ho v nng cao cm th ca tuyn thng thn i vi adrenocorticotropin. * Nhu cu v ngun vitamin C Acid'ascorbic c tng hp nhiu loi vi sinh vt, cy ci, ng vt. Nga, ln, gia cm vn cn vitamin C Ring tru, b, d, cu c kh nng t tc hon ton. Vitamin C bi tit ra ngoi theo nc tiu, m hi v c di dng CO 2 hi th, cng lao ng cng cao th nhu cu v vitamin C cng ln, cc trng thi bnh l nh st hoc c thai c th cng i hi tng lng vitamin C trong khu phn. Hin tng gim vitamin C trong mu, trong nc tiu, trong dch v c coi l nhng triu chng ng k v lm sng ca nhiu bnh. Vitamin C c gan, thn; mu, sa, bp ci, c chua, hnh, t, cam chanh, l tng...

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