XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
333
T9: P–7
Vibrational studies of steroid hormone and anti-cancer drug
Makunda M. Borah
1
, and Gomti Devi Thongam
1
1
Department of Physics, North-Eastern Regional Institute of Science and Technology, Nirjuli-
791109, Arunachal Pradesh, India, e-mail: tgdevi26@gmail.com
Cancer is human related disease which is of major concern in today’s world. Furthermore
Estrogen, due to the proliferation of cells in uncontrollable manner leads to breast cancer. Anti-
estrogen drugs are available to block the action of Estrogens and thereby preventing the
proliferation of breast cancer cell. Estradiol is a hormone responsible indirectly for such type of
dreadful disease [1] and Tamoxifen is an anti-cancer drug [2] for the treatment of breast cancer.
Study of these two molecules can unveil the properties of these molecules and their interacting
environment. In the present study the vibrational properties of Estradiol, Tamoxifen molecules
and in their interacting states have been studied using spectroscopic techniques such as FTIR
and Raman respectively. The optimized geometrical structure and vibrational frequencies of the
molecules in monomer and dimer states have been computed using DFT method. The basis set
has been taken as b3lyp/6-31+g(d,p) [3]. The Raman spectra of Estradiol and Tamoxifen are
shown fig.1 and fig.2 respectively. SERS spectra of the molecules are also recorded and
compare with normal Raman spectra.
0
1000
2000
3000
4000
0
1000
2000
3000
4000
R
am
an
I
nt
en
si
ty
Wave number(cm
-1
)
Estradiol experimental(Raman)
0
1000
2000
3000
1000
1200
1400
1600
1800
R
am
an
in
te
ns
ity
Wave number(cm
-1
)
Tamoxifen experimental (Raman)
Fig. 1.
Fig. 2.
The stable geometrical parameters and vibrational wave numbers were calculated based on
potential energy distribution (PED) using vibrational energy distribution analysis (VEDA)
program. NBO analysis is carried out to confirm the charge transfer and bond formation
between the molecules.
Keywords: peak frequency; estradiol; DFT
Acknowledgment
The author is thankful to DST India for the FIST facility provided to Physics Department, NERIST.
References
[1] V. Khmelnytskyy, Ukrainskii biokhimicheskii zhurnal 80 (2008) 82.
[2] T. Citrate. NCI. August 26, 2015. Retrieved 28 November 2015.
[3] J.P. Merrick, D. Moran, L. Radom, J. Phys. Chem. A 111 (2007) 11683.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
334
T9: P–8
Optimization of sulfonylureas geometry in respect to experimental
FT-IR bands applied in identification of their cyclodextrin complex
Mikołaj Mizera
1
, and Judyta Cielecka-Piontek
1
1
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Poznan University of Medical
Sciences, Grunwaldzka 6, 60-780 Poznań, Poland, e-mail: mikolajmizera@gmail.com
Support of experimental FT-IR spectra analysis with theoretically computed bands gained
popularity thanks to spread of quantum chemical methods like Density Functional Theory or
semiempirical parametrized models. The noticeable drawback of modelling molecules is
unreliable result depending on its conformation which, in experimental sample, is not necessary
the lowest energy one. The possible answer for the issue is optimization of molecule in respect
to similarity of its theoretical spectrum to experimental one. The method could be adopted to
analysis of complex FT-IR spectra involving cyclodextrins – API systems.
The aim of the study was to develop theoretical approach able to optimize geometry of
molecules in respect to similarity to the experimental FT-IR spectra. The method was applied
for the case of investigation of sulfonylureas in complexes with cyclodextrins.
The following derivative free optimization methods including Powell method, Differential
Evolution as well as derivative based methods including Broyden–Fletcher–Goldfarb–Shanno
(BFGS) and Conjugate gradient were used in order to optimize torsional angles of molecule. On
each step of optimization torsional angles were varied resulting in new geometries. Each
geometry was locally optimized using MOPAC 2016 package implementing Parametrization
Model 7 and FT-IR peaks were calculated. The cost function was distance measure between
main experimental and theoretical peaks in spectra in respect to torsional angles. All routines
were implemented in Python 2.7 environment with SciPy v0.19.0 and openbabel 2.3.0 libraries.
Experimental samples were β-cyclodextrin complexes with three sulfonylureas: gliclazide,
glimepride and glibenclamide as well as their physical mixtures and pure substances. Complexes
were prepared with co-precipitation methods. The identification of β-cyclodextrin complexes
was conducted using DSC method. FT-IR spectrum of each sample was recorded in KBr tablets
and analyzed with support of presented theoretical approach.
The study showed that energy of molecule does not correlate with similarity of computed
spectra with experimental one. Optimization of torsional angles in respect to spectra similarities
allowed to reduce calculated distance between theoretical and experimental spectra.
Theoretically modelled low energy conformer of isolated molecule does not reflect the
actual conformation in experimental sample. Presented method of torsional angles optimization
was able to optimize initial low-energy conformation of three investigated sulfonylureas in order
to acquire theoretical spectrum fitted to experimental one. With support of presented theoretical
methods changes in experimental spectra of sulfonylureas in complexed systems could be
assigned to calculated normal modes of API and thus get more detailed insight into interacting
domains of cyclodextrins and sulfonylurea.
Keywords: derivatives of sulfonylurea; cyclodextrins; theoretical approach; Fourier-transform infrared
Acknowledgment
The scientific work was funded from the budget resources for science in the years 2015-2018 as a research
project within the program "Diamond Grant".
This research was supported in part by PL-Grid Infrastructure.
Dostları ilə paylaş: |