Os complexos de platina são importantes no desenvolvimento de drogas anticancerígenas. Sua citotoxicidade pode ser afetada pelos ligantes abandonadores, devido ao mecanismo da reação de hidrólise que ocorre antes da ligação do complexo ao DNA. Os grupos não-abandonadores, como as diaminas lipofílicas, também podem afetar a velocidade de entrada do composto na célula. Neste trabalho é descrita a síntese de novos complexos de platina(II) contendo ligantes oxalato e derivados de etilenodiamina N-substituída por uma cadeia carbônica longa de tamanho variável. Os produtos foram caracterizados por análise elementar, espectroscopia de absorção na região do infravermelho e ressonância magnética nuclear de ¹H, 13C e 195Pt. A atividade biológica dos complexos foi investigada em linhagens de células tumorais (A549, B16-F1, B16-F10, MDA-MB-231) e não-tumorais (BHK-21 e CHO). O tamanho da cadeia carbônica afetou a citotoxicidade e os complexos com oxalato mostraram-se menos citotóxicos do que os análogos com cloretos.

Platinum complexes play an important role in the development of anticancer drugs. Their cytotoxicity can be influenced by the nature of the leaving ligands, due to the hydrolysis reaction that occurs prior to the binding of the platinum complex to DNA. Also, non-leaving groups such as lipophilic diamines may affect cellular uptake. In this work, we describe the synthesis of platinum(II) complexes having oxalato and long chain aliphatic N-alkyl ethylenediamines as ligands. The products were characterized by elemental analyses, infrared spectroscopy and ¹H, 13C and 195Pt NMR spectroscopy. Biological activity was assessed against tumor cell lines (A549, B16-F1, B16-F10, MDA-MB-231) and non-tumor cell lines (BHK-21 and CHO). The length of the carbon chain affects the cytotoxicity and the oxalato complexes were less cytotoxic than the respective chloride-containing analogues.

Different toxoplasma antigens were entrapped within liposomes and evaluated, in this form, for their ability to protect Swiss mice against toxoplasma infection: soluble tachyzoite antigen (L/TAg), tissue cyst (L/CAg), tachyzoite plus tissue cyst (L/TCAg) or purified antigen of tachyzoite (L/pTAg). The protein used in L/pTAg was purified from tachyzoites using a stage-specific monoclonal antibody which reacted at a molecular weight of 32 kD in SDS PAGE and silver stain using reduced condition. To compare the immuno-adjuvant action of liposomes and of Freund's Complete Adjuvant (FCA), another group of mice was immunized with soluble tachyzoite antigen (STAg) emulsified in FCA (FCA/TAg). Control groups were inoculated with (STAg) alone, phosphate-buffered saline (PBS), FCA with PBS (FCA/PBS) and empty liposomes (L/PBS). Mice were inoculated subcutaneously with these antigens six, four and two weeks before a challenge with 80 tissue cysts of the P strain of Toxoplasma gondii orally. All mice immunized with or without adjuvant showed a humoral response, as measured by Elisa. However, no correlation was found between antibody titer and protection against the challenge. All mice immunized with L/pTAg or L/TCAg survived (100), whereas 80% and 90% of mice from groups which received respectively PBS or FCA/PBS and L/PBS died. All mice immunized with antigens entrapped within liposomes (L/TAg, L/CAg, L/TCAg and L/pTAg) showed low numbers of intracerebral cysts.