Ricardo Gomes da Rosa

Acaricidal activity of limonene, limonene oxide and β-amino alcohol derivatives on Rhipicephalus (Boophilus) microplus

Limonene, limonene oxide and eight beta-amino alcohol derivatives obtained by synthesis were investigated for the effect on egg hatchability and mortality rates of newly hatched larvae of the cattle tick Rhipicephalus (Boophilus) microplus. At the doses between 10 microg/ml and 2.5 microg/ml all the compounds were highly lethal to the larvae and some of them showed activity at lower concentrations. The effect on the eggs hatchability was observed in all the treatments.

Synthesis and in vitro activity of limonene derivatives against Leishmania and Trypanosoma

The synthesis and in vitro activity of R(+)-Limonene derivatives against Leishmania and Trypanosoma cruzi strains are reported. Seven compounds have shown better in vitro activity against Leishmania (V.)braziliensis than the standard drug pentamidine. Additionally, we have identified two promising new anti-T. cruzi limonene derivatives.

Studies on the experimental variables effects on rhodium catalyzed hydroformylation of unsaturated fatty esters and comparison of [RhH(CO)(PPh3)3] and [RhCl3.3H2O] as starting catalytic precursors

Hydroformylation experiments were performed with technical-grade methyl oleate (MO) and soybean oil (SO) using [RhH(CO)(PPh3)3] and [RhCl3.3H2O] (double bond/Rh = 745) as catalyst precursors modified or not by triphenylphosphine. [RhH(CO)(PPh3)3] shows 100% conversion and 80-91% selectivity to aldehydes in only 4h for both substrates under mild conditions (100 °C, 40 bar, CO/H2 = 2:1, ligand/Rh = 10:1). Despite the rapid isomerisation of the soybean oil, producing trans isomers and conjugated dienes, no effects were observed on its further conversion to aldehydes. The reaction of soybean oil conducted with pure [RhCl3.3H2O] produced only conjugated dienes, and when this precursor was modified with triphenylphosphine (ligand/Rh = 10:1) no reaction was observed at all. Curiously, yellow crystals corresponding to the complex [Rh(Cl)(CO)(PPh3)2] were quantitatively isolated at the end of the reaction .

Synthesis of limonene β-amino alcohol derivatives in support of new antileishmanial therapies

A series of seven limonene beta-amino alcohol derivatives has been regioselectively synthesised in moderate to good yields. Two of these compounds were found to be significantly effective against in vitro cultures of the Leishmania (Viannia) braziliensis promastigote form in the micromolar range. The activities found for 3b and 3f were about 100-fold more potent than the standard drug, Pentamidine, in the same test, while limonene did not display any activity. This is the first report of antileishmanial activity by limonene beta-amino alcohol derivatives.

Hidroformilação do oleato de metila catalisada por complexos de ródio

In this work, we describe the hydroformylation of methyl oleate catalyzed by several rhodium complexes. Parameters including total pressure, phosphorous/rhodium and CO/H2 ratio, temperature and phosphorous ligands were scanned. Total conversion of the starting double bonds was achieved while maintaining excellent selectivity in aldehydes.