João Batista Neves DaCosta

COMPOSTOS ORGANOFOSFORADOS PENTAVALENTES: HISTÓRICO, MÉTODOS SINTÉTICOS DE PREPARAÇÃO E APLICAÇÕES COMO INSETICIDAS E AGENTES ANTITUMORAIS

This paper is a review of the history, synthesis and application of organophosphorus compounds, especially of those of pentavalent phosphorus, such as phosphoramidates, phosphorothioates, phosphonates and phosphonic acids with insecticide and anticancer activities. The organophosphorus compounds with agrochemical applications show great structural variety, They include not only insecticides, but also fungicides, herbicides, and others. The large variety of commercially available organophosphorus pesticides is remarkable. Even more interesting is the high efficiency of some organophosphorus compounds as anticancer agents such as cyclophosphamide and its derivatives.

SYNTHESIS, CHARACTERIZATION, MOLECULAR MODELING AND BIOLOGICAL ACTIVITY AGAINST ARTEMIA SALINA OF NEW SYMMETRICAL BISPHOSPHORAMIDATES

A series of N,N′-bis(dialkylphosphoryl)diamines were prepared by Todd-Atherton reaction of dialkylphosphites with symmetrical diamines in a biphasic system. They were characterized by IR, 1 H-NMR, 13C-NMR and mass spectroscopy. Compounds with butoxy groups, isobutoxy groups and isopropoxy groups on the phosphorus atoms showed the lowest LD50 values when tested against Artemia salina. All other compounds that showed LD50 values higher than 363 ppm are considered non toxic. The results of a molecular modeling study suggest that the biological activity of the compounds may be related to AChE inhibition. Contrary to classical organophophorus AChE inhibitors, the compounds synthestized in this study do not possess a good leaving group, which suggests that they may act only as reversible inhibitors.

Synthesis and Characterization of New Symmetrical Bisphosphonates

In order to search for new chelating agents, widely employed methodologies in the chemistry of organophosphorus compounds such as the Michaelis-Arbuzov and Michaelis-Becker reactions were used to synthesize new bisphosphonates in high yields. The importance of the synthesis of these compounds resides in their potential capability of complexing different metals, all the more so because bisphosphonates have been widely employed in the diagnosis and therapy of several bone diseases, such as osteoporosis and hypercalcemia, as extracting agents for alkaline, alkaline earth, and transition metals, and also as reaction catalysts. All bisphosphonates synthesized were characterized by IR, 1 H-NMR, 13 C-NMR, 31 P-NMR, and mass spectroscopy.

Diastereoselective Synthesis of New Dialkylphosphorylhydrazones

A series of 22 dialkylphosphorylydrazones (dialkyl ester, N′-[(1E)-(R1 phenyl)methylene]-phosphorohydrazidic acid), 20 of them new, along with three new N,N′-bis (diisobutylphosphorylthioamide)diamines (bis-[diisobutyl ester), N-thioxomethylene]-, diamine)phosphora-midic acid, were prepared and characterized by IR, 1H NMR, 13C NMR, 31P NMR, and mass spectrometry. The analysis of 1H NMR, 13C NMR, 31P NMR, and NOE spectra confirmed the observation of the single diastereoisomer E in the synthesis of dialkylphosphorylydrazones. The results of a molecular modeling study performed in order to investigate the mechanism of the synthesis of dialkylphosphorylydrazones are in agreement with the experimental results, i.e., the favored formation of diastereoisomer E over Z.

Synthesis, characterization, and biological activity of a new class of dialkylphosphorylhydrazone derivatives of isatin

Sixteen dialkylphosphorylhydrazones were synthesized by condensation of phosphorylhydrazines with substituted isatins. Products were characterized by FTIR, 1H-NMR, 13C-NMR, and 31P-NMR. Fungicidal activities of these compounds against Rhizoctonia solani and Fusarium oxysporum were also evaluated. Some compounds inhibited the growth of Rhizoctonia solani and Fusarium oxysporum by 43% and 51%, respectively. These compounds exhibited no effects on germination of lettuce seeds (Lactuca sativa L).

Dialkylphosphorylhydrazones as potent tyrosinase inhibitors

Nineteen dialkylphosphorylhydrazones with different substituents at the aromatic ring were evaluated as potential tyrosinase inhibitors, which could then be used as efficient agents in the control of pigmentation disorders. The inhibition activity was measured by a modified Patil and Zucker UV-Vis method. Briefly, the assays were carried out with solutions containing phosphate buffer, L-3,4-dihidroxyphenylalanine (L-DOPA), (EDTA), tyrosinase and varying concentrations of organophosphorus compounds. The formation of dopachromone was determined by monitoring the absorbance at 475 nm. Three compounds were found to be the most active compounds of the series (IC50 = 105 ± 20 µmol L-1), (IC50 = 127 ± 16 µmol L-1) and (IC50 = 188 ± 27 µmol L-1), being three to seven times more active than ascorbic acid (IC50 = 730 µmol L-1), used as a standard. The most active compound is only 1.5 times less potent than the commercial kojic acid (IC50 = 69.4 µmol L-1). This study may lead to the discovery of potent agents against very important pigmentation disorders including hyperpigmentation.

Síntese, caracterização e estudo da atividade inibitória de novas dialquilfosforilarilidrazonas sobre o crescimento de tripanossomatídeos

A new series of dialkylphosphorylhydrazones was synthesized through the condensation of aromatic aldehydes with different phosphorylhydrazines. All synthesized compounds were characterized by IR, 1H-NMR, 13C-NMR and 31P-NMR spectroscopies. The in vitro investigation of the activity of these compounds against Leishmania amazonensis promastigotes and epimastigotes of T. cruzi, showed an efficient inhibition of proliferation, at non toxic concentrations to mammalian cells. The results have shown some derivatives as potential antiparasitic agents against trypanosomatids.