• Parasites, Hosts and Diseases
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• 제61권4호
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• pp.449-454
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• 2023

Free-living amoebae (FLA) rarely cause human infections but can invoke fatal infections in the central nervous system (CNS). No consensus treatment has been established for FLA infections of the CNS, emphasizing the urgent need to discover or develop safe and effective drugs. Flavonoids, natural compounds from plants and plant-derived products, are known to have antiprotozoan activities against several pathogenic protozoa parasites. The anti-FLA activity of flavonoids has also been proposed, while their antiamoebic activity for FLA needs to be emperically determined. We herein evaluated the antiamoebic activities of 18 flavonoids against Naegleria fowleri and Acanthamoeba species which included A. castellanii and A. polyphaga. These flavonoids showed different profiles of antiamoebic activity against N. fowleri and Acanthamoeba species. Demethoxycurcumin, kaempferol, resveratrol, and silybin (A+B) showed in vitro antiamoebic activity against both N. fowleri and Acanthamoeba species. Apigenin, costunolide, (-)-epicatechin, (-)-epigallocatechin, rosmarinic acid, and (-)-trans-caryophyllene showed selective antiamoebic activity for Acanthamoeba species. Luteolin was more effective for N. fowleri. However, afzelin, berberine, (±)-catechin, chelerythrine, genistein, (+)-pinostrobin, and quercetin did not exhibit antiamoebic activity against the amoeba species. They neither showed selective antiamoebic activity with significant cytotoxicity to C6 glial cells. Our results provide a basis for the anti-FLA activity of flavonoids, which can be applied to develope alternative or supplemental therapeutic agents for FLA infections of the CNS.

• Journal of Microbiology and Biotechnology
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• 제27권8호
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• pp.1401-1408
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• 2017

Petiveria alliacea L. (Phytolacaceae) is a medicinal plant with a broad range of traditional therapeutic properties, including the treatment of dysentery and intestinal infections caused by protozoan parasites. However, its effects against Entamoeba histolytica have not been reported yet. We investigated the antiamoebic activity present in the leaves of P. alliacea Antiamoebic activity was evaluated in methanolic and aqueous extracts, as well as in the hexanic, methanolic, and EtOAc fractions. The P. alliacea methanolic extract showed a better antiamoebic activity than the aqueous extract with an $IC_{50}=0.51mg/ml$. Likewise, the hexanic fraction was the most effective fraction, showing a dose-dependent activity against E. histolytica, with an $IC_{50}=0.68mg/ml$. Hexanic subfraction 12-19 showed the highest antiamoebic activity at 0.8 mg/ml, producing 74.3% growth inhibition without any toxicity in mammal cells. A major component in subfraction 12-19 was identified as isoarborinol, which produced 51.4% E. histolytica growth inhibition at 0.05 mg/ml without affecting mammal cells. The P. alliacea leaf extract has antiamoebic activity that can be attributed to a major metabolite known as isoarborinol.