Transcript Presentation

Saratov Fall Meeting 2015
OPTICAL PROPERTIES
OF CHITOSAN IN AQUEOUS
SOLUTIONS
OF L- AND D-ASCORBIC ACIDS
Olga N. Malinkina*1,2, Anna B. Shipovskaya1,2, Olga F. Kazmicheva2
[email protected]
1 - Institute of Chemistry, Saratov State University
2 - Research and Education Institution of Nanostructures and Biosystems,
Saratov State University
Abstract
For most biologically active compounds there is a
close correlation between biological activity and
their spatial structure, which is used to establish by
the optical methods, in particular spectropolarimetry,
based on the phenomenon of optical isomerism.
In this study optical activity of chitosan solutions in
different solvents by spectropolarimetric method
was investigated.
It was found that the spectra of optical rotation of
chitosan solutions in ascorbic acid in significantly
different in magnitude and sign from chitosan
solutions in other solvents.
FACTORS INFLUENCING on the OPTICAL ACTIVITY
for Low Molecular Substances
for Macromolecular Substances
Quantum-mechanical theory of
optically isotropic and anisotropic
media
Semi-empirical
methods of calculation
Optical purity
Concentration Temperature
Nature of the solvent Wavelength
The configuration of a chiral center
 INTERFERENCE of the CHIRAL
CENTERs of the CHAINs
 CHAIN CONFORMATION
(MOLECULAR STRUCTURE)
 STEREOREGULARITY
(COPOLYMERS)
3
• Biospecificity
• Optical activity
• Biocompatibility
• The ability to form polyelectrolyte complexes
• Antioxidant properties
4
5
Formula
Structural
formula
L-Ascorbic Acid
γ-lactone 2,3dihydro-L-gulonic
C6H8O6
acid
М,
at. un.
рК
+23
176
*
D-Ascorbic Acid
γ-lactone 2,3dihydro-D-gulonic
acid
Identification,
using
Е300
antioxidant
4.1
11.8
–23
D-Lactic Acid
α-hydroxypropionic acid
C3H6O3
*
90
Succinic Acid
ethan-1,2dicarboxylic acid
C4H6O4
118
Е270
preservative
Е363
antioxidant
3.8
–2.6
4.2
5.6
−
Biot’s
Law
(deg·ml·dm-1·gram -1)
or
(deg·cm2·decagram -1)
α – measured angle of optical rotation of the solution, degree
α0 – measured angle of optical rotation of the solvent, degree
Сп – polymer concentration in solution, g/dl
l – pathlength, dm
The spectra of the optical activity of the
solutions were recorded on an automatic
spectropolarimeter PolAAr 3001 by Optical
Activity Ltd (GB) in the wavelength range
λ = 365-589 nm
in a thermostated cell at 25°C.
6
Chitosan solution
in D-ascorbic acid
L - ascorbic acid
λ, nm
D - ascorbic acid
λ, nm
Chitosan solution
in L-ascorbic acid
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in different molar relationships
chitosan : ascorbic acid
1 - Chs : L-Asc A= 1 : 2
2 - Chs : L-Asc A= 1 : 1
1’ - Chs : D-Asc A= 1 : 2
2’ - Chs : D-Asc A= 1 : 1
λ, nm
8
СChs = 0.3 g/dl
СAcid = 1.0 – 10.0 g/dl
In the Ascorbic Acid
= +93
λ, nm
In the Succinic Acid
= – 14
In the Lactic Acid
= – 23
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Conclusions
• Optical properties of solutions of CHs in ascorbic, lactic and succinic
acids were studied by method of ORD.
• The essential differences in the values ​of specific optical rotation of
chitosan solution in different solvents were found.
• Values ​of specific optical rotation [α] 25λ for the chitosan solution in
ascorbic, lactic acid succinic acids were +93, -23 and -14 respectively.
• The no essential differences in the values ​of specific optical rotation of
chitosan solution in L- and D-ascorbic acids were found.
• The influence of molar ratio on the optical activity [α] of chitosan
solution of ascorbic acid was found.
• The interaction between chitosan and ascorbic acid is spatial different
from interaction with other organic and nonogranic acids.
• Perhaps this explains the synergistic effect high therapeutic action of
multicomponent systems based on chitosan and ascorbic acid.