Figura 1 Structura vitaminei C

COOH COOH O C=O

C=O                            C-OH HO C-OH O

H C-OH enolizare C-OH ciclizare O sau C-OH

H C-OH HC-OH H₂O HO HC

HO- CH HO-CH HO-CH HO-CH

CH₂OH CH₂OH CH₂OH CH₂OH

Acid 2-ceto- Acid 2,3-dienol- γ-lactona Acid ascorbic

L-gulonic L-gulonic (Acid ascorbic) (γ-lactona acidului

L-gulonic)

Figura 2 Structura acidului dehidroascorbic

O=C O=C

C-OH O O=C O

C-OH -2H O=C

HC +2H HC

HO-CH HO-CH

CH₂OH CH₂OH

Acid ascorbic Acid dehidroascorbic

Figura 3 Structura acidului idonic

HOOC - CH - CH - CH - CH - CH₂OH

OH OH OH OH

Figura 4 Degradarea acidului ascorbic si dihidroascorbic

COOH

O=C O=C COOH COOH

C-OH O oxidare O=C O oxidare O=C +H₂O Acid oxalic

C-OH O=C energica O=C

HC lenta HC +H₂O HC-OH +1/2 O₂ COOH

HO-CH HO-CH HO-CH HC-OH

CH₂OH CH₂OH CH₂OH HO-CH

COOH

Acid Acid L-dehidro- Acid L-diceto- Acid L-treonic

asorbic ascorbic gulonic

incalzire H O

C

CO₂ C

HC O

CH

HC

Furfurol

Figura 5 Structura moleculara a vitaminelor A si a derivatilor acestora

17 16 19 20

H₃C CH₃ CH₃ CH₃

Referat: Tratamentul complex al luxatiei recidivante de rotula: orthopedic sau chirurgical? Lucrare: Articulatia genunchiului - meniscurile genunchiului

1 7 9 11 13 15

2 6 8 10 12 14 CH₂OH

Vitamina A₁ (Retinol)

CH₃

4 18

CH₂OH

Vitamina A₂ (3,4-Dehidroretinol)

CH₂

CH₂OH    Vitamina A₃

Neovitamina A₁ (Neovitamina A₃)

CH₂ OH (13 cis-Retinol)

O

C                 Retinal (Retinen)

H

COOH      Acid retinoic

O

C                 - Dehidroretinal

H

COOH      Acid 3,4 - dehidroretinoic

Figura . .

C₁₉H₂₇-CH=CH-H₂₇C₁₉

β - caroten

β - caroten O₂+saruri

oxigeneaza biliare

O

2C₁₉H₂₇-C

H

Retinaldehid-                  Retinal Oxidare (retinaloxidaza)

reductaza NADPH+H⁺ +1/2 O₂

NADP⁺

C₁₉H₂₆-CH₂-OH                            C₁₉H₂₇-COOH

Retinol Acid retinoic

Figura . .Principalele carotenoide provitaminice A

β - caroten

α - caroten

Figura . .. Izomerul Neovitamina A_a

CH₂OH

13 - cis - Retinol

(Neovitamina A_a)

Figura . .. Structura moleculara a chitolului CH₃ H₃C

CH₃ CH₃ CH₃ OH

CH₃ OH CH₃ CH₃ CH₃

CH₃

Figura . . . . . . . . . . . .

2H₂O                                              carotenhidroxilaza

C₁₉H₂₇-CH=CH-H₂₇C₁₉ C₁₉H₂₇- CH- CH-H₂₇C₁₉

OH OH

β - caroten Derivat hodroxilat

NADP⁺

O + NADPH + H⁺

C₁₉H₂₇-CH₂OH + C₁₉H₂₇-C C₁₉H₂₇-CH₂OH

H

Retinol                              Retinal +O Retinol

C₁₇H₂₇-COOH

Acid retinoic

Figura . . Schema simplificata a procesului vederii

RODOPSINA

Intuneric Lumina

Fotoizomerizare

OPSINA

11-cis-Retinal all-Trans- Retinal

Oxidare Reducere

Izomerizare

11-cis-Retinol all-Trans-Retinol

Sange