Antiamoebic activity

The antiamoebic activities of 2-imidazolylaminomethylenemalonate (1659) were investigated via in vitro and in vivo tests [84IJC(B)342]. 

Cimanga K, Kambu K, Tona L, Hermans N, Apers S, Totte J, Pieters L, Vlietinek AJ. Antiamoebic Activity of Iridoids from Morinda morindoides Leaves. Planta Medica. 2006 72 751-753. 

Emetine and cephaeline are both potent inhibitors of protein synthesis, inhibiting at the translocation stage. They display antitumour and antiviral as well as antiamoebic activity, but are too toxic for therapeutic use. In recent studies, O-methylpsychotrine has displayed fairly low effects on protein synthesis, but a quite potent ability to curb viral replication through inhibition of HIV-reverse transcriptase. This may give it potential in the treatment of AIDS. 

A number of N-(4-substituted benzyl)acetamides of the general formula 7 were synthesized, which showed promising antiamoebic activity. The most effective compounds of this series were 8 and 9 of which chlorphenoxamide, clefamide (9), was found to be useful in treating intestinal amoebiasis in human [15-18]. Replacement of the OH group in clefamide with OEt gives etofamide (10), which exhibited a high order of amoebicidal efficacy [19]. 

Vanadium compounds containing thiosemicarbazide- and hydrazide-derived ligands, such as 26 and 27 in Figure 5.15, exhibit antiamoebic activity against Entamoeba histolytica. This water-borne amoebic protozoan parasitises the human intestines and in some cases other visceral organs, especially the liver. It is the aetiological agent of amoebiasis (also known as amoebic dysentery) and thus responsible for amoebic colitis and intestinal and liver abscesses. Symptomatic patients typically suffer from abdominal pain, diarrhoea... 

Plant products have also played a significant role in the treatment of another parasitic disease, amoebiasis. The root and corm extracts of Cephaelis ipecuanhana were traditionally and empirically for the treatment of dysentry and the active ingredient emetine was isolated in 1817. It was not until 1912 that the antiamoebic activity of the alkaloid emetine was placed on a rational basis. Another product cepahaeline proved to be less active than its methyl ester emetine. In the early 1960s the derivative dehydroemetine was shown to be more active against E. histolytica and less toxic than the parent compound. 

The bisindole alkaloids macrocarpamine (323), macralstonine acetate (semisynthetic), and villalstonine (322) from A. angustifolia were found to possess significant in vitro antiamoebic activity against E. histolytica and P. falciparum, but were 4-8 times less potent than emetine against E. histolytica, and 15-50 times less potent than chloroquine against P. falciparum (240). Villalstonine and macrocarpamine were... 

Fig. 2.3 Some quinoxaline motifs with antiamoebic activity...

Abid M, Azam A (2006) Synthesis, characterization and antiamoebic activity of l-(thiazolo[4,5-b] quinoxaline-2-yl)-3-phenyl-2-pytazoline derivatives. Biootg Med Chem Lett 16 2812-2816. doi 10.1016/j.bmcl.2006.01.116... 

GHOSHAL s, KRISHNA PRASAD B N and LAKSHMi V (1996), Antiamoebic activity of Piper longum fruits against Entamoeba histolytica in vitro and in vivo ,J Ethnopharma-... 

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