Anti-intestinal protozoan activities of 1-hydroxy-2-hydroxymethylanthraquinone from Coptosapelta flavescens

ObjectiveTo investigate the antiprotozoal activity of medicinal plant extracts and isolated active compounds from the most active plant.MethodsTwenty one medicinal plants with ethnobotanical use in Thailand, which were claimed to have anti-diarrhoeal or anti-parasitic activity, were screened for their anti-intestinal protozoan activity against Entamoeba histolytica (E. histolytica) and Giardia intestinalis (G. intestinalis). The most active compound was isolated and tested against E. histolytica and G. intestinalis.ResultsAn acetone extract of Coptosapelta flavescens was the most active against both E. histolytica and G. intestinalis (minimal inhibitory concentration=125 and 15.63 μg/mL, respectively). Two anthraquinones and one naphthoquinone were isolated. The compound 1-hydroxy-2-hydroxymethylanthraquinone was the most active chemical against E. histolytica and G. intestinalis with minimal inhibitory concentration values of 20 and 2.5 μg/mL, respectively. In time killing assay, the percentage of viable G. intestinalis, when compare to control, after expose to compound 1-hydroxy-2-hydroxymethylanthraquinone showed significantly (P<0.05) lower than when exposed to a standard drug, metronidazole, at 6 and 12 h of incubation time. While for E. histolytica, its activity was comparable to metronidazole.ConclusionsThese observations provide preliminary evidence that 1-hydroxy-2-hydroxymethylanthraquinone from Coptosapelta flavescens can be considered to be a potential anti-parasitic agent against E. histolytica and G. intestinalis infections.