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THE INTERACTION OF THE HEME GROUP WITH CHLOROQUINE,
CHLORPROMAZINE AND DESIPRAMINE INVESTIGATED BY UVVIS
AND RESONANCE RAMAN SPECTROSCOPIES
Vanessa A. Otelo1, Antonio C. Sant’Ana2, Carla M. S. Menezes1, Dalva L. A. Faria2*
1 LAPEN – Faculdade de Ciências Farmacêuticas, Universidade de São Paulo
2 LEM – Instituto de Química, Universidade de São Paulo
Most of P. falciparum
strains have shown
band.3 When the laser line is within the Q bands
resistance to chloroquine (CQ), taken as the
non-totally symmetric modes are also enhanced,
ideal antimalarial.1 Intrinsic antiplasmodic
activity was observed when modulating agents
In all Raman spectra of heme in the presence
were assayed with Brazilian CQ-resistant P.
of CQ there is a broadening of the bands
. Tricyclic modulating agents as
indicating a possible weak π interaction. In CPZ
chlorpromazine (CPZ) and desipramine (DSP)
and DSP such interaction is less favorable due
show stereo-electronic resemblance with CQ.
to a lack in molecular planarity. The band at
The similar features suggest the interaction of
1373 cm-1 do not undergo any shift indicating
these tricyclic compounds with the heme group,
that the charge density at the FeIII site is
which is the probable site of the action of CQ.
preserved4 with the three compounds. A band at
To understand the kind of interaction of these
403 cm-1 is enhanced in the association with
species with heme group, associations with each
compound were studied by ultraviolet-visible
coordination of these tricyclic compounds with
FeIII by displacement of the chloride ligand.
These data may be related to more localized electronic charge in the N and S cyclic atoms as
RESULTS AND DISCUSSION
well as by the inherent angular planes of these tricyclic compounds, as indicated by AM1 semi-
empiric calculations (Spartan’02 Linux).
investigated in phosphate buffer (pH=7.4). The compounds and heme concentrations were 0.2
mM and 0.1 mM, respectively. In the case of Raman experiments only the spectra of heme
interaction of heme with CQ occurs through π
clouds due to the high charge delocalization.
The N and S cyclic atoms from CPZ and DSP
interactions take place, characterized by the
species represent possible coordination sites at
decrease in the intensities of the heme bands,
heme FeIII atom. The displacement of chloride
without any change in the frequencies. The
by CPZ and DSP as ligand of heme group does
Soret bands assigned to monomer and dimer
not affect significantly the charge density on the
heme species show change in their relative
intensities indicating that the monomer-dimer
equilibrium is affected by the interaction with
The authors thank CNPq, FAPESP and CAPES
observed in the visible region, undergo an
for financial support and grant of scholarships.
increase in the intensities (hyperchromism) in
the association, suggesting a change in the
1 Snow, R.W; Guerra, C.A.; Noor, A.M.; Myint,
, 2005, 434
The RR spectra were obtained in the Q band
2 Menezes, C.M.S., Ferreira, E.I. Drug Des. Rev.,
region with excitation at 632.8 nm and in the
Soret band region with the 514.5 and 488.0 nm
3 Choi, S., Spiro, T.G., Langry, K.C., Smith, K.M. J.
laser lines. Significant differences in such
Am. Chem. Soc.
, 1982, 104
spectra can be observed due to the enhancement
4 Spiro, T.G., Terner, J. Pure Appl. Chem.
, 1983, 55
of the totally symmetric A1g modes when 145.
exciting radiation are in resonance with Soret
BIOGRAPHICAL SKETCH Provide the following information for the Senior/key personnel and other significant contributors in the Follow this format for each person. DO NOT EXCEED FOUR PAGES. Professor, Department of Physical Medicine and eRA COMMONS USER NAME (credential, e.g., Rehabilitation, Professor, Department of Pediatrics IO N/TRAINING (Begin with baccalaureate or other initial
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