Semisynthesis of Antitrypanosomal p-Quinone Analog Possesing the Komaroviquinone Pharmacophore.

A p-quinone analog having the komaroviquinone pharmacophore fused with a more conformationally flexible cycloheptane ring, was semisynthesized from natural demethlsalvicanol isolated from Perovskia abrotanoides via four steps in 26% overall yield. The IC50 for the antitrypanosomal activity of the analog was 0.55 µM.

In vitro antitrypanosomal activity of some phenolic compounds from propolis and lactones from Fijian Kawa (Piper methysticum).

During our search to discover new antitrypanosomal compounds, eight known plant compounds (three phenolic compounds and five kawa lactones) were evaluated for in vitro activity against Trypanosoma brucei brucei. Among them, we found two phenolic compounds and three kawa lactones possessing an α-pyrone influenced antitrypanosomal property. In particular, ß-phenethyl caffeate, farnesyl caffeate and dihydrokawain exhibited high or moderate selective and potent antitrypanosomal activity in vitro. We detail here the antitrypanosomal activity and cytotoxicities of the compounds, in comparison with two commonly used antitrypanosomal drugs (eflornithine and suramin). Our findings represent the first report of the promising trypanocidal activity of these compounds.

In vitro antitrypanosomal activity of bis(bibenzyls)s and bibenzyls from liverworts against Trypanosoma brucei.

During the course of our screening program to discover new antitrypanosomal compounds, 17 known plant aromatic compounds [12 bis(bibenzyls)s and 5 bibenzyls] were evaluated for in vitro activity against Trypanosoma brucei brucei. Sixteen compounds were found to exhibit antitrypanosomal activity. In particular, three compounds, marchantin A (1), plagiochin A (5) and 2(R)-2-isopropenyl-6,7-dihydroxy-4-(2-phenylethyl)dihydrobenzofuran (16) demonstrated moderate selective and potent antitrypanosomal activities in vitro. We detail here the antitrypanosomal properties and cytotoxicities of the compounds in comparison with two commonly used therapeutic drugs, eflornithine and suramin. Our finding represents the first report of the promising trypanocidal activity of these compounds. The research also provides valuable insight into structure-activity relationships and the possible mode of action of the compounds.

In vitro antimalarial activity of prenylated flavonoids from Erythrina fusca.

Ethyl acetate (EtOAc) extract from the stem bark of Erythrina fusca showed a antimalarial activity against the multi-drug-resistant strain (K1) of Plasmodium falciparum, and six flavonoids, lupinifolin (1), citflavanone (2), erythrisenegalone (3), lonchocarpol A (4), liquiritigenin (5), and 8-prenyldaidzein (6), were isolated from the extract. Diprenylated flavanone 4 showed a notable antimalarial activity (IC(50); 1.6 microg/mL); however 1 and 3 did not show the activity, even though these compounds possessed prenylated substitution.

Antimalarial activity of biflavonoids from Ochna integerrima.

During the screening of antimalarial substances, the 80% EtOH extract from the outer bark of Ochna integerrima Merr. (Ochnaceae) was shown to have a good anti-malarial activity (IC50 value: 6.5 microg/mL) whereas extracts from the inner barks of O.integerrima showed no antimalarial activity. Biflavanone (1), which had not been found previously from a natural plant source, was isolated as a potent antimalarial active ingredient (IC50 value: 80 ng/mL) from the extract of the outer barks. The stereoisomer of 1 ( = compound 2) was also isolated from this plant; however, its activity was significantly lower than that of 1.