TIỂU LUẬN SINH HOÁ

8/7/2019 TIU LUN SINH HO

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OH

CH3

S

N

CH3

OH

NH2

CH3

CH3

NH2

N

N

S

N+

OH

TIU LUN SINH HO A TI:

1. M u:- Nm 1910, Funk phn lp c vitamin B1 u tin t tiu b ca go,

sau t men bia.- 1931 William v Windaus tm thy cng thc chnh xc ca vitamin B1.- 1936 nhm cc nh khoa hc thnh cng tng hp ra vitamin B1:

Andersad v Westphanl, ri Jansen v Williams.

2. Ni dung:2.1.Cu to:Vitamin B1 cn c gi l thiamine hay anerien, c to nn t mt vng

thiazol v t mt vng pyrimidine lin kt vi nhau bng nhm methylen. N ccu to nh sau:

2-methyl 5-oxymethyl 4-metyl 5-oxyethyl-thiazolaminpyrimidin

Vitamin B1 (thiamine) Dng mui thiamine chlorideV cng vi nhm amin trong phn t vitamin B1 cn c nguyn t S cho nnngi ta gi n l thiamine (do ting hy lp thion l lu hunh).

2.2. Tnh cht vt l- Vitamin B1 c mi ging mi men bia, tn ti di dng tinh th mutrng, tan nhiu trong nc, mt t tan trong alcol.

- Rt nhy cm:+Vi nhit v b phn hu phn ln khi lm chn (100oC) hoc khi x l

trong l vi sng. Ngc li khi lm lnh hm lng ca n s khng thay itrong thc n.

+ Vi tc nhn oxy ho tt c cc thay i ca lng oxy ho dn n mthot tnh sinh hc.

+ Vi tnh Acid ca mi trng: Bn (hot tnh khng b gim khi un

nng trong dung dch c pH = 3, 140

o

C).+ Vi s ion ho.

1

N

N

NH2

CH3

N+

S

CH3

OH

Cl-


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CH3

CH3

NH2

N

N

S

N+

OH

aseDecarboxyl

CH3CH

O

CH3 C

O

SHCO

OHCCH3

O

.CoA

LTPP

C

O

OHCCH3

O

Acetyl-CoA

+ N b ph hu hon ton bi qu trnh ra thc phm.- V c tnh, vitamin B1 khng c v phn ng c hi ca vitamin ny

thuc loi him, c th dng liu ln n 500mg mi ngy.

2.3.Tnh cht ho hc- tr nn hot ng, vitamin B1 phi c lin kt vi nhiu phn t P

(phn b rng trong t bo dng hot ng coenzyme-thiamine-pyrophosphate(carbosylase)).

Coenzyme-thiamine-pyrophosphate (cacbonsylase)

- Thiaminpyrophosphate tham gia vo phn ng: decarboxyl ho,decarboxylase, cc ketose acid, cng nh phn gii v tng hp cc - ketoseacid (nh cc ng ketose)

Pyruvic acid Acetaldehyde

Pyruvic acid- Nit ca vng thiazol c cc tnh cht kim v n c th kt hp vi HCl

to thnh mui trong cng thc trnh by trn ngha l dng mui caammonium base 4 ln th (thiamine chlorid), vitamin B1 tn ti trong mitrng acid. i vi mi trng trung tnh mi trng kim vitamin B1 c cutrc khc rt c trng: Vng thiazol b ph v; khi trong phn t thiaminxut hin nhm aldehyde v nhm sulfulhydryl (-SH) t do.

Thiamine (dng c nhm aldehyl v nhm SH t do)

-Phn ng to thiocrome:

2

N+

S

CH3

CH2CH2OP2O6H

N

NCH3

NH2

OH

SH

CH3

N

CH3

NH2

N

N

O

CO2

NADH+ + H+NAD+ +C0ASH


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CH3

NCH3 N

N

S

N

OHO

NH2

CH3

CH3 N

N

S

N

OH

Thiamine

Thiocrome

- Phn ng vi thuc th diazo cho dung dch phc cam.

2.4. Tc dng sinh l:Vitamin B1 rt cn thit i vi qu trnh sinh trng v pht trin ca c

th.- Thiu vitamin B1 trong c th s gy ra:

+ Tim mch b tn thng, h thng thn kinh b xo trn.+ Bnh thiu vitamin B1 cn gi l bnh Beri-beri (bnh t ph), xut hin

khi c th thiu nghim trng vitamin B1 trong khong 3 thng. c trng bicc triu chng vim dy thn kinh ngoi vi v ri lon tim mch.

C 2 dng:Beri-beri kh biu hin thn kinh ngoi vi nh ri lon cm gic

chi, gim phn x,c th b teo c gy lit 2 chn.

Beri-beri t vi triu chng kh th khi gng sc, tim p nhanh,nh trng ngc, ph, gi chung l suy tim, c th gy ti t vong.+ Hi chng Wernicke - korsakoff: L mt hi chng thn kinh - tinh thn

hay gp bnh nhn nghin ru gy thiu vitamin B1 nng ko di. Cc c mt b yu, bnh nhn kh nhn ln hoc nhn sang hai bn, c khi mt phnghng v mt mi, c khi mt b chng git nhn cu v ngi lo o. Cc biuhin tinh thn thng l gim trm trng kh nng nh v hc nhng cc qutrnh t duy khc li t b nh hng. C khi bnh nhn qun hn nhng chuynva xy ra trong ngy nhng li ba ra nhng chuyn qua.

+ phng, tr bnh Beri-beri, nn n go mi, bo qun tt, khng b

mc hng. Chn loi ch xay xt 1 ln (theo tiu chun 100 kg thc ly 70 kggo). Khng nn n go xay xt qu trng. Cn n thm nhng thc phm cnhiu vitamin B1 hng ngy nh u tng, u xanh, u en, u trng, lc,vng, tht (b, ln), bu dc, gan (b, ln), lng trng, rau ti nh (gincm, dip, x lch, gi u xanh, u c ve, u a, u H Lan, ti). Hay ta cth dng thuc tim. Tuy nhin khi dng ng tim c th b d ng a nsc phn v c th b t vong. Nn lu , khi dng vitamin B1 liu cao hocdng ng tim l cha bnh ch khng phi b sung theo kiu h trdinh dng thng thng, nh dng ng tim tr thiu ht vitamin B1nng.

2.5. Tc dng sinh ho:

3

N

Fe3

H2


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C

O

OHCCH

3

O

OH

N+

S

CH3

CH2CH

2OP

2O6H

N

NCH3

NH2

CH

CH3

2C O

OH

N+

S

CH3

CH2CH2OP 2O6H

N

NCH3

NH2

CH

CH3

- Thiaminpyrophosphate l nhm hot ng ca enzyme c hiu xc tc sphn gii pyruvic acid trong c th, khi thiu vitamin B1 pyruvic acid s tch lytrong c th gy c cho h thng thn kinh.

+

pyruvic acid

Thiaminepyrophosphate

Hp cht trung gian

+ CO2

Oxyethylthiaminpyrophosphate

- Vitamin B1 gi vai tr ch o trong chuyn ha nng lng, nht l

chuyn ha glucid, vitamin B1 cho php v iu ha kh nng s dng glucid.

Nu t chc thiu vitamin B1 th kh nng chuyn ha glucid s khng v

glucose, thc n chnh ca t bo thn kinh cng b thiu. Vitamin B1 khng tc

ng trc tip, nhng ging nh tt c cc vitamin nhm B, n c chuyn i

thnh coenzym, c bit nh qu trnh can thip ca magesi. V th nhu cu

vitamin B1 i vi c th t l thun vi nhu cu nng lng

- Tc ng n chc nng ca cc m thn kinh ph thuc vo lng glucose

hp thu vo c th. Ngoi ra n cn ng vai tr dn truyn xung thn kinh ti

h thn kinh trung ng (no, ty sng) cng nh h thn kinh ngoi bin (mng

li thn kinh ni lin h thn kinh trung ng vi c v cc ni tng), kch

thch hot ng tr c v tr nh, tham gia tng hp cht bo.

- Nhn t ngon ming: kch thch s to thnh mt loi enzyme tham gia vo

qu trnh ng ho thc n, kch thch cm gic thm n.

4

N+

S

CH3

CH2CH2OP2O6H

N

NCH3

NH2
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2.6.Chu trnh Vitamin B1

- Hp thu v chuyn ho: Thiamine c hp thu ch yu phn hng hitrng ca rut non. Nu ch mt phn nh thiamine c n vo, n s c hpthu bi mt c ch vn chuyn tch cc ph thuc Natri

- Coenzym TPP (tin thn ca thiamine trong c th) khng i qua cmng t bo, tr mng hng cu. TPP trong thc phm phi c kh

phosphoryl thnh thiamine trc khi c c th hp thu. Sau TPP li cto thnh t thiamine v phosphat trong t bo.

- Ngi trng thnh cha 30 70 mg thiamine, khong 80% trong s dng TPP. Mt na thiamin ca c th nm trong c. C th khng c ngun dtr thiamin c hiu, tuy nhin mc thiamin trong c, no, gan, thn c th tnggp i trong qu trnh iu tr. Trong thi gian thiu ht thiamine, mc ti thiu

trong cc m trn c th h xung cn mt na bnh thng, tr m no.Thiamin c bi tit khi c th di dng thiamine - acid acetic v mt scht khc sn sinh trong qu trnh chuyn ho.

2.7. Ch nh, nhu cu s dng - ngun cung cp vitamin B

2.7.1. Ch nh s dng:

- Vitamin B1 c ch nh s dng trong cc trng hp sau:

+Ngi gi hoc ngi n theo ch khng cn i.

+ Trong tt c cc trng hp ri lon hp th, bnh tiu ha hoc bnh

gan, dng thuc hp ph hoc bong nim mc d dy.

+ Trong tt c nhng trng hp nn ma, tiu chy.

+ Khi qu trnh bi tit tng : i tho nht hay i tho ng, iu tr li

tiu ko di. c bit, trong i tho ng, B1 to iu kin d dng cho

qu trnh ng ha glucose.- Nhu cu B1 tng ln lc c thai.

+ Ng c ru mn tnh.

+ Nhng ngi ung nhiu caf hoc nhng ngi n c ti (mt vi

enzym ca c ti ph hy B1).

+ Nhng tr em b bnh di truyn v chuyn ha B1.

+ Nhng bnh nhn b Beriberi.

+ B1 cn c ch nh i km (hoc khng) vi B6 v B12 iu trdy thn kinh b vim trong au thn kinh ta, au lng, vo c, au dy

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thn kinh, thng tn thn kinh (chn p hay ct dy thn kinh).

+ Ngun dinh dng khng bo m nhu cu.

+ Ri lon hp thu vitamin h tiu ha (nh ngi dng thuc gim cn

theo c ch gim thiu lng cht bo hp thu rut c th b thiu vitamin tan

trong du).

2.7.2. Nhu cu:

- Nhu cu vitamin B1 c lin quan trc tip n lng ng bt (nh

cm ta n hng ngy). n nhiu tinh bt go s cn nhiu vitamin B1 chuynha tinh bt thnh cht dinh dng

- Tnh theo nng lng ca khu phn. C 1000 kcal n vo th nhu cu

vitamin B1 l 0,4 mg. i vi vitamin B1, nhu cu cn hng ngy khong

1,5mg.

2.7.3. Ngun cung cp:

Vitamin B1 c trong cc ht ng cc, da, tht nc, lng trng, gan, thn.

Ngun vitamin B1 trong mt s thc phm:Ht u tng: 0,54 mg%Ht u xanh: 0,7 mg%Vng: 0,3 mg%Rau cn ty: 0,06 mg%Rau dn: 0,08 mg%

Rau khoai lang: 0,13 mg%Rau ngt: 0,07 mg%Bi: 0,04 mg%Chui : 0,04 mg%

Nho: 0,05 mg%Tht ln nc: 0,9 mg%Tim ln: 0,32 mg%Sa m: 0,12 mg%

2.8. Du hiu thiu, tha v b sung Vitamin B1

2.8.1. Du hiu thiu:

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- Khi thiu vitamin B1 (Thiamin) gy hng lot cc ri lon nh t b, hihp, to bn, khng ngon ming, chn n, n khng tiu, gim nhu ng tiuha(do gim tit acid dch v), ri lon tiu ha, ...

2.8.2. Du hiu tha:- Khng c triu chng khi tha vitamin B1- Hin nay, khng c nguy c qu liu vitamin, v li c tnh ca

vitamin B1 rt yu. Do ngi ta ch nhn rng, liu cao ch c th gy litiu.

2.8.3. Cch b sung:- Khi b bnh beri beri, s b sung thuc vitamin s lm gim nhanh cc

triu chng. Thuc vitamin B1 c dng hin nay l loi thng phm honton tng hp, dng dng mui thiamin clorhydrat, bromhydrat hay nitrat.

- Tim hoc ung vitamin B1- Cung cp qua ngun thc phm giu vitamin B1 hng ngy.

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TIỂU LUẬN SINH HOÁ