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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
* [email protected]

INTRODUCTION
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 falciparum. 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 CONCLUSIONS
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 ACKNOWLEDGEMENTS
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 REFERENCES
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Source: http://lem.iq.usp.br/workshop/ws2006/abstracts/p_ws_OteloVA.pdf