In vitro and in vivo antimalarial activity of ferrochloroquine, a ferrocenyl analogue of chloroquine against chloroquine-resistant malaria parasites.

Previous studies have shown that ferrochloroquine (FQ) exhibited an antimalarial activity against Plasmodium spp. The present work confirmed this activity, described the curative effect on P. vinckei and investigated the FQ toxicity in vitro and in vivo. The in vitro and in vivo growth inhibition of P. falciparum and P. berghei N, respectively, showed that FQ antimalarial activity was 1.5-10 times more potent than chloroquine. FQ completely inhibited the in vivo development of both chloroquine-susceptible and resistant P. vinckei strains and protected mice from lethal infection at a dose of 8.4 mg kg(-1) day(-1) given for 4 days subcutaneously or orally. This curative effect was 5-20 times more potent than chloroquine, according to the strains' resistance to chloroquine. At this curative dose, no clinical changes were observed in mice up to 14 days after the last administration. Nevertheless, the acute toxicity and lethality of ferrochloroquine seemed to be dependent on gastric surfeit. The FQ security index determined in vitro confirmed that it might be a promising compound.

Novel ferrocenic artemisinin derivatives: synthesis, in vitro antimalarial activity and affinity of binding with ferroprotoporphyrin IX.

Following our search for novel compounds with high antimalarial activity, a series of artemisinin (QHS) derivatives containing a ferrocenic nucleus was prepared and tested in vitro against Plasmodium falciparum strains. Two new metallocenic derivatives (1 and 3) were found as potent as QHS. All compounds showed a capacity to bind with ferroprotoporphyrin IX. A decrease in the Soret band absorbance of ferroprotoporphyrin IX, resulting from the addition of different drugs concentrations, was shown. The association stoichiometry of compounds to ferroprotoporphyrin IX appears to be 1:2 at equilibrium, with an intermediate 1:1 complexation. These results appear to strengthen the role of adducts between artemisinin derivatives and heme in generation of artemisinin radicals. Such interaction of artemisinin ferrocenyl derivatives with ferroprotoporphyrin IX and its biological significance could form a basis in future drug development.

Synthetic ferrocenic mefloquine and quinine analoguesas potential antimalarial agents.

A few years ago we proposed a strategy for the synthesis of new ferrocene-chloroquine analogues replacing the carbon chain of chloroquine by hydrophobic ferrocenyl moieties. Now, this strategy has been applied to the antimalarial amino-alcohols class to afford new potentially active analogues of mefloquine and quinine bearing a substituted ferrocenic group. The pathway used for the synthesis of the mefloquine analogues includes the coupling of an aminomethyl substituted ferrocene carboxaldehyde with a lithio quinoline compound. On the other hand, the synthesis of quinine analogues was ensured by the 'inverse' reaction of a lithio aminomethyl ferrocene with a quinoline carboxaldehyde. The configurations of each diastereoisomer were unambiguously determined by spectroscopic data. The mechanistic interpretations were fully discussed. Ferrocenyl analogues of mefloquine and quinine exhibited a lower antimalarial activity than mefloquine and quinine themselves. Comparing optical isomers, those isomers dissimilar to ferrocenyl derivatives presented better antimalarial activities than those similar to ferrocenyl.

Synthesis and antifungal activity of a ferrocene-fluconazole analogue.

A novel ferrocene fluconazole analogue was synthesized and its antifungal properties investigated against yeast strains of medical importance, including those intrinsically resistant to fluconazole. In vitro tests revealed a slight increase in fungal growth and a reversal of the effect of fluconazole at minimal inhibitory concentrations.

Synthesis and antimalarial activity in vitro of potential metabolites of ferrochloroquine and related compounds.

In man, the two major metabolites of the antimalarial drug chloroquine (CQ) are monodesethylchloroquine (DECQ) and didesethylchloroquine (di-DECQ). By analogy with CQ, the synthesis and the in vitro tests of some amino derivatives of ferrochloroquine (FQ), a ferrocenic analogue of CQ which are presumed to be the oxidative metabolites of FQ, are reported. Desmethylferrochloroquine 1a and didesmethylferrochloroquine 2 would be more potent against schizontocides than CQ in vitro against two strains (HB3 and Dd2) of Plasmodium falciparum. Other secondary amino derivatives have been prepared and proved to be active as antimalarial agents in vitro, too.

In vitro antimalarial activity of a new organometallic analog, ferrocene-chloroquine.

The in vitro activities of new organometallic chloroquine analogs, based on 4-amino-quinoleine compounds bound to a molecule of ferrocene, were evaluated against chloroquine-susceptible, chloroquine-intermediate, and chloroquine-resistant, culture-adapted Plasmodium falciparum lineages by a proliferation test. One of the ferrocene analogs totally restored the activity of chloroquine against chloroquine-resistant parasites. This compound, associated with tartaric acid for better solubility, was highly effective. The role of the ferrocene in reversing chloroquine resistance is discussed, as is its potential use for human therapy.

Synthesis and antimalarial activity in vitro and in vivo of a new ferrocene-chloroquine analogue.

The antimalarial activities of ferrocenic compounds mimicking chloroquine and active upon chloroquine-resistant strains of Plasmodium falciparum were evaluated. Four 7-chloro-4-[[[2-[(N,N-substituted amino)methyl]ferrocenyl]methyl]amino]quinoline derivatives have been synthesized; one of them, 1a, showed high potent antimalarial activity in vivo on mice infected with Plasmodium berghei N. and Plasmodium yoelii NS. and was 22 times more potent against schizontocides than chloroquine in vitro against a drug-resistant strain of P. falciparum.