SPECTROSCOPIC OF THE FORMATION

OF ASSOCIATE BETWEEN IN MICRO

Marta Szymula, Stanisław Radzki*, Department of Radiochemistry

*Department of M. Curie-Skłodowska University,

INVESTIGATION EQUILIBRIUM VITAMIN C AND VITAMIN EEMULSIONS

Edyta Mazur and Urszula Kubićand Colloid Chemistry Inorganic ChemistryM.C. Skłodowska Sq. 2, 20-031 Lublin, Poland

PURPOSE

The main purpose of our studies included examination of association of water-soluble antioxidant ascorbic acid (vitamin C, H2A, AA) and hydrophobic α-tocopherol (α-T) in microemulsions.

It was found that activity of antioxidants depends not only on their molecular structure but also on the reaction environment. We chose microemulsion as a medium of antioxidants activity studies, having in mind the fact that many substances of hydrophilic and hydrophobic character (e.g. antioxidants) can be solved or solubilized in such a systems.

We also took into account the idea that the design of microscopic molecular assemblies which mimic the microenvironment present in the biological systems can contribute a great deal to the understanding of naturally occurring processes.

REACTIVE FORMS OF OXYGEN (ROS)

Radiationion

Ultrasounds

Smoke of cigarette

NAME

SYMBOL

NAME

SYMBOL

Tlen singlet

21O

Radical alkoxy

RO

Ozon

3O

Radical peroxide

ROO

Radical hydroxyperoxide

(=radical anion hydroxyperoxide )

2OH

Peroxide (=hydroxyperoxide)

ROOH

Radical anion peroxide

O

2

Oxygen dioxide

22OH

Radical hydroxyl

OH The most reactive chemical creature

VITAMIN C OXIDATION REACTION

O

OH OH

H

O

CH2OHOHH

O

O O

H

O

CH2OHOHH

+2H+

-2H+

+2e-

-2e-

L-ascorbic acid

L-dehydroascorbic acid

The absorption spectrum of L-ascorbic acid dissolved in water at pH 2.0 reveals a λmax of 243nm (ε=10000 L mol-1 cm-1) which undergoes a red shift to 265nm (ε=16 500 L mol-1 cm-1) when pH goes up to 7.0 as a result of ionization of the C-3-OH proton.

-TOCOPHEROL, VITAMIN E FAT-SOLUBLE VITAMIN

O

OH

CH3

CH3

CH3

CH3

CH3

CH3CH3

CH3

The activity of the E-vitamers is associated with the phenolic hydroxy group, which readily undergoes oxidation.

-TOCOPHEROL OXIDATION REACTION

O

CH3

CH3

CH3

CH3

OH

R

O

CH3

CH3

CH3

CH3

O

R

O

CH3

CH3

CH3

OCH3

OH

R

+

Utlenianie

Redukcja

+H2O

-H2O

α-Tocopherol oxidation by strong oxidizers leads to chroman-5,6-chinon

α-Tocopherol oxidation by week oxidizers leads to α-tokopherylo-p-chinon

MEMBRANE CELL MODELSOLUBILIZATION

D. Chiras, Human

Biology

ZWIĄZEKZWIĄZEKPOLARNYPOLARNY

MICELE ODWRÓCONEMICELE ODWRÓCONE

ZWIĄZEK NIEJONOWYZWIĄZEK NIEJONOWY

MICELE NORMALNEMICELE NORMALNE

ZWIĄZEK AMFOFILOWYZWIĄZEK AMFOFILOWY

SOLUBILIZATION

Microemulsions and liquid crystals are the most popular delivery systems for functional cosmetics and pharmaceutical ingredients. Aggregated systems of self-assembling molecules are able to prevent chemical degradation of the active ingredient.

Solubilization – the bringing into solution of insoluble organic substances be surfactant solution above cmc. The process involves incorporation of solubilizate into the surfactant micelle.

ANTIOXIDANTS OF VARIOUS HYDROPHILIC/HYDROPHOBIC CHARAKTER

VITAMIN CH2O

H2O

H2O

H2O

H2O

H2O

H2O

VITAMIN E

OIL

L-Ascorbic acid is easily dissolved in the microemulsion region of SDS, pentanol, water system

CALCULATIONS OF EQUILIBRIUM CONSTANTS FOR α-TOCOPHEROL BINDING TO ASCORBIC ACID

nAAAAAAAA )T-(...)T-()T-(T- T-2

T-

]T-][)T-([

])T-([

1

n

nn AA

AAK

][]T-[......]T-[]T-[1

]T-[.........]T-[]T-[0

212

211

212

212110 AAKKKKKK

KKKKKKKA

nn

nnnn

A - absorbance 0 - molecular absorbance coefficient for the starting propyl gallate 1 and K1, 2 and K2, ... , etc. - molecular absorbance coefficient an association constants for complexes with stoichiometry 1:1, 1:2, ... , etc., respectively [AA0] and [-T] - analytical concentration of ascorbic acid and α-tocopherol

The values of the association constants K [L mol-1] for ascorbic acid with α-tocopherol associates in various microemulsions

 

 

Solution composition

System K [L·mol-1]

6% SDS, 1% pentanol 93% water O/W

λ 264 nm; 26 846±16%

λ 246 nm; 25 834±24%

6% SDS, 22% pentanol 72% water bicontinous

λ 264 nm; 26 773±37%

λ 250 nm; 26 420±30%

6% SDS, 77% pentanol 17% water W/O

λ 264 nm; 106 300±6%

λ 250 nm; 82 620±7%

CONCLUSIONS•α-Tocopherol forms 1:1 molecular complexes with ascorbic acid, which appears to be due to the hydrogen bond.

•The associate formed were decomposed with time.

•Evolution of absorption spectra during the study of molecular complex formation goes in three steps through well-defined isosbestic points.

•The association constants were calculated using the curve-fitting procedure.

Consuming more antioxidants helps provide the body with tools to neutralize harmful free radicals.

200 220 240 260 280 300 320 340

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

1% pentanol 6% SDS93% water

Wavelenght [nm]A

bso

rb

an

ce

Vitamin C + vitamin E

264 nm

292 nm

202-212 nm

200 220 240 260 280 300 320 340

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

22% pentanol 6% SDS 72% water

Wavelenght [nm]

Ab

so

rb

an

ce

Vitamin C + vitamin E

264 nm

292 nm

202- 230 nm

200 220 240 260 280 300 320 340

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

77% pentanol 6% SDS 17% water

Wavelenght [nm]

Ab

so

rb

an

ce

Vitamin C + vitamin E

264 nm

292 nm

202- 230 nm

Vitamin C + vitamin E

0 5 10 15 20 25

0.0

0.5

1.0

1.5

2.0

Vitamin E CM.

105

Ab

so

rb

an

ce

77% pentanol 6% SDS17% water

264 nmRsq = 0.991

K = 106300±6%

250 nmRsq = 0.999

K = 82020±7%

Vitamin C + vitamin E

0 5 10 15 20 25

0.0

0.5

1.0

1.5

2.0

Vitamin E CM.

105

Ab

so

rb

an

ce

1% pentanol 6% SDS93% water

264 nmRsq = 0.918

K = 26846±16%

246 nmRsq = 0.958

K = 25834±24%

Vitamin C + vitamin E

0 5 10 15 20 25

0.0

0.5

1.0

1.5

2.0

Vitamin E CM.

105

Ab

so

rb

an

ce

22% pentanol 6% SDS72% water

264 nmRsq = 0.842

K = 26773±37%

250 nmRsq = 0.883

K = 26420±30%

200 220 240 260 280 300 320 340

0

1

2

3

4

Wavelenght [nm]A

bso

rb

an

ce

1% pentanol 6% SDS 93% water

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Ab

so

rb

an

ce

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

220 nm, 0 h 264 nm, 0 h 292 nm, 0 h

De Job's plot for the vitamin C and vitamin E system

x vitamin E

200 220 240 260 280 300 320 340

0

1

2

3

4

Wavelength [nm]

Ab

so

rb

an

ce

22% pentanol 6% SDS 72% water

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Ab

so

rb

an

ce

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4 220 nm, 0 h 264 nm, 0 h 292 nm, 0 h

De Job's plot for the vitamin C and vitamin E system

x vitamin E

200 220 240 260 280 300 320 340

0

1

2

3

4

Wavelength [nm]

Ab

so

rb

an

ce

x vitamin E

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Ab

so

rb

an

ce

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

220 nm, 24 h264 nm, 24 h292 nm, 24 h

De Job's plot for the vitamin C and vitamin E system

77% pentanol 6% SDS 17% water

200 220 240 260 280 300 320 340

0

1

2

3

4

Wavelenght [nm]A

bso

rb

an

ce

1% pentanol 6% SDS 93% water

x vitamin E

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Ab

so

rb

an

ce

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

220 nm, 24 h264 nm, 24 h292 nm, 24 h

De Job's plot for the vitamin C and vitamin E system

200 220 240 260 280 300 320 340

0

1

2

3

4

Wavelength [nm]

Ab

so

rb

an

ce

x vitamin E

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Ab

so

rb

an

ce

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

220 nm, 24 h264 nm, 24 h292 nm, 24 h

De Job's plot for the vitamin C and vitamin E system

22% pentanol 6% SDS 72% water

200 220 240 260 280 300 320 340

0

1

2

3

4

Wavelength [nm]

Ab

so

rb

an

ce

x vitamin E

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Ab

so

rb

an

ce

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

220 nm, 24 h264 nm, 24 h292 nm, 24 h

De Job's plot for the vitamin C and vitamin E system

77% pentanol 6% SDS 17% water