350
Volume 5, Issue 10: Special Issue
(EJAR)
ISSN: 2181-2020
MPHAPP
THE 6TH INTERNATIONAL SCIENTIFIC AND PRACTICAL
CONFERENCE
“
MODERN PHARMACEUTICS: ACTUAL
PROBLEMS AND PROSPECTS
”
TASHKENT, OCTOBER 17, 2025
in-academy.uz
SYNTHESIS OF GALACTOMANNAN DIALDEHYDE DERIVATIVES AND
INVESTIGATION OF THEIR PHYSICAL AND CHEMICAL PROPERTIES
Amonova D.M
1
.
Boydedaev A.A
1
.
Karimov M. Sh
1
.
Kalonova M.O
1
.
Muhitdinov B.I
1
.
Turaev A.S
1
.
Huang Y
2
.
Wang H
2
1
Institute of Bioorganic Chemistry, Uzbekistan Academy of Sciences, Tashkent city, Republic
of Uzbekistan
2
Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai city, China
e-mail: amonovadilnoza@gmail.com
https://doi.org/10.5281/zenodo.17337447
Galactomannan is a polysaccharide mainly composed of D-mannose and D-galactose, linked
by α-1,4 and
-1,6 glycosidic bonds. These connections define the structure of the polysaccharide
and influence its physicochemical properties. The structure can vary, with different branching from
galactose residues affecting its overall characteristics. Dialdehyde derivatives of galactomannan are
novel compounds formed through oxidation or chemical modification. These derivatives enhance the
polymer's rigidity, solubility, and mechanical strength. They can also react with primary amino
groups, forming imino (azomethine) bonds and Schiff bases, which are significant in various
applications. This study explores the production of low molecular weight galactomannan dialdehyde
derivatives, their reaction conditions, and their physicochemical properties.
In this study, we developed and characterized dialdehyde derivatives through the periodate
oxidation of low molecular weight galactomannan, obtained by depolymerizing guar galactomannan
at a concentration of 20 mg/ml in distilled water. A freshly prepared 0.2 N sodium periodate (NaIO
4
)
solution was added, maintaining a galactomannan to sodium periodate molar ratio of 1:0.1-1.0. The
reactions took place in the dark at 40°C for 1 to 24 hours. To stop the reaction, 0.5 ml of ethylene
glycol was added. The resulting product was precipitated with 96% (v/v) ethanol (1:5 ratio), washed
four times with 70% (v/v) ethanol to remove impurities, dialyzed in the dark, filtered, and lyophilized
to obtain the final product. The structures of the galactomannan dialdehyde derivatives were analyzed
using IR and
13
C NMR spectroscopy.
In the IR spectroscopy studies, the dialdehyde derivatives of galactomannan exhibited
absorbance characteristic of N-H and O-H stretching vibrations in the range of 3200-3600 cm⁻¹.
Signals related to H–C–H (-CH₂-) and C=O (aldehyde) stretching vibrations were observed at 2820-
2950 cm⁻¹ and 1732 cm⁻¹, respectively. Absorbances in the 1300-1400 cm⁻¹ region correspond to the
deformational vibrations of C–H bonds, while those at 1060 cm⁻¹ are attributed to the valence
vibrations of C–O–C bonds in the glucopyranose ring. Absorbances at 894 cm⁻¹ are characteristic of
the β-(ManC1−O−ManC4) glycosidic bonds between mannose residues in the polymer chain.
Additionally, absorbances corresponding to the Man(C6)−O−Gal(C1) glycosidic bonds between
mannose and galactose residues were identified at 870 cm⁻¹. In the
13
C NMR spectrum, signals with
high intensity corresponding to the hemiacetal and gem-diol forms of polysaccharides were identified
in the ranges of 87-98 ppm. Specifically, in the range of 80.10-80.17 ppm, high-intensity signals
correspond to the carbon atoms ManC2 and ManC3 in the hemiacetal and gem-diol forms,
351
Volume 5, Issue 10: Special Issue
(EJAR)
ISSN: 2181-2020
MPHAPP
THE 6TH INTERNATIONAL SCIENTIFIC AND PRACTICAL
CONFERENCE
“
MODERN PHARMACEUTICS: ACTUAL
PROBLEMS AND PROSPECTS
”
TASHKENT, OCTOBER 17, 2025
in-academy.uz
respectively. This indicates that the periodate oxidation in galactomannans primarily occurs at the
carbon atoms ManC2 and ManC3.
This study developed low molecular weight galactomannan dialdehyde derivatives and
thoroughly investigated their properties. The obtained galactomannan dialdehydes were analyzed
using IR and
13
C NMR spectroscopy techniques. The IR spectroscopy results indicated that the C=O
(aldehyde) stretching was observed at 1732 cm⁻¹. The
13
C NMR spectrum confirmed the unique
characteristics of the galactomannan structure, showing that the periodate oxidation occurred at the
ManC2 and ManC3 carbon atoms. The resulting dialdehyde derivatives play a crucial role in
enhancing the polymer's rigidity, solubility, and mechanical strength, creating new opportunities for
their use in various industrial and biological applications.
