mannich-bases and pyronaridine

2,5-Dichloro-4-methyl-benzo[c][2,7]naphthyridine (1) reacted with aromatic amines selectively by substitution at the 5-position to yield the amidines 2. The 4-aminophenol 2c could also be synthesized by cleavage of the ether 2b. The structure of 2c was proved by X-ray crystal analysis. Aminomethylation of 2c yielded the amodiaquine analogue 3. The mono- and bisaminomethylated derivatives 4 and 5 were obtained by reaction of compound 1 with phenol Mannich base hydrochlorides. Compounds 3-5 were tested in vitro for antimalarial activity using chloroquine-sensitive and resistant Plasmodium-falciparum strains. The highest activities were shown by the pyronaridine-type compounds 5a and 5b with IC50 values of approximately 200 nM.

Topics: Amodiaquine; Animals; Antimalarials; Crystallography, X-Ray; Mannich Bases; Naphthyridines; Plasmodium falciparum; Quinones; Spectrophotometry, Infrared; Spectrophotometry, Ultraviolet

The ethyl 4-chlorobenzofuro[3,2-b]pyridine-3-carboxylate (2) reacted with the hydrochlorides of the mono- and bis-phenol Mannich bases 3 to yield the amodiaquine and pyronaridine analogues 4. The chloroquine analogue 6 was formed by melting 2 with the novaldiamine base (5) in phenol. The most active compound 4c inhibited the growth of the malaria parasite Plasmodium falciparum with an IC50 of 500 nM.

Topics: Amines; Amodiaquine; Animals; Antimalarials; Benzofurans; Chemical Phenomena; Chemistry, Physical; Mannich Bases; Naphthyridines; Plasmodium falciparum

We have compared the ex vivo antimalarial activity of 12 new quinoline di-Mannich base compounds containing the 7-dichloroquinoline or 7-trifluoromethylquinoline nucleus with amodiaquine, chloroquine, and pyronaridine using the Saimiri-bioassay model. Each compound was administered orally (30 mg/kg of body weight) to three or more noninfected Saimiri sciureus monkeys, and serum samples were collected at various times after drug administration and serially diluted with drug-free (control) serum. In vitro activity against the multidrug-resistant K1 isolate of Plasmodium falciparum was determined in serum samples by measuring the maximum inhibitory dilution at which the treated monkey serum inhibited schizont maturation in vitro. Of the 12 Mannich bases tested, 8 were associated with levels of ex vivo antimalarial activity in serum greater than those of amodiaquine, chloroquine, or pyronaridine 1 to 7 days after drug administration. Further studies were carried out with four of these compounds, and the results showed that the areas under the serum drug concentration-time curves for the four compounds were between 7- and 26-fold greater than that obtained for pyronaridine. Activity against four multidrug-resistant strains of P. falciparum was also much greater in serum samples collected from monkeys after administration of these four compounds than in serum samples collected after administration of pyronaridine or chloroquine. These findings suggest that these four quinoline Mannich base compounds possess a very marked and prolonged antimalarial activity and that further studies should be performed to determine their value as antimalarial drugs.

Topics: Amodiaquine; Animals; Antimalarials; Chloroquine; Mannich Bases; Microbial Sensitivity Tests; Naphthyridines; Plasmodium falciparum; Quinolines; Saimiri; Structure-Activity Relationship

The activities of Mannich base antimalarials, including pyronaridine, have been explored against drug-sensitive (Plasmodium berghei N) and chloroquine-resistant (Plasmodium yoelii NS) rodent malaria parasites in vivo. Lines of these parasites have been developed with resistance to pyronaridine, amodiaquine, or WR 228,258. The responses and patterns of cross-resistance of these lines to Mannich bases and other blood schizontocides are inconsistent. It is concluded that some Mannich bases may prove still to be of value inthe treatment of chloroquine-resistant Plasmodium falciparum infection.

Topics: Aminoquinolines; Amodiaquine; Animals; Antimalarials; Drug Resistance; Malaria; Mannich Bases; Mice; Naphthyridines; Plasmodium berghei; Plasmodium yoelii