Amebicidal activity of plant extracts from Southeast Asia on Acanthamoeba spp.

Chu, Dan-My T.; Miles, Howard; Toney, Denise M.; Ngyuen, Chi; Marciano‐Cabral, Francine

doi:10.1007/s004360050480

Cited by 41 publications

(24 citation statements)

References 28 publications

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“…A variety of drugs has been clinically tested, but none of these agents has proven to be effective against all the isolates of Acanthamoeba (Chu et al 1998). Some successful treatment regimens have included propamidine isothionate and dibromopropamidine, although the disease may sometimes still progress in patients treated with these compounds (Auran et al 1987;Binder 1989;Aksozek et al 2002).…”

Section: Resultsmentioning

confidence: 99%

In vitro evaluation of the amebicidal activity of Pterocaulon polystachyum (Asteraceae) against trophozoites of Acanthamoeba castellanii

et al. 2008

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The crude extract and hexane, dichloromethane, and methanol fractions obtained from the aerial parts of Pterocaulon polystachyum (Asteraceae) were assayed against Acanthamoeba castellanii, a free-living ameba that causes acute amebic keratitis. Because of its capacity to form cysts, some strains of this protozoan are excellent opportunists and therapy resistant, necessitating a search for new drugs in order to develop more dynamic therapies that make it easier for patients to maintain long-term treatment. In this context, plants with medicinal properties have been analyzed. The broad-spectrum activity against a range of pathogenic fungi shown by extracts of P. polystachyum, together with the use of antifungal drugs as antiprotozoals, made it important to evaluate the amebicidal activity of these plant extracts against A. castellanii. The greatest activity was observed in the treatment with the hexane fraction, which lysed approximately 66% and 70% of the trophozoites in 48 and 72 h, respectively, preventing encystment.

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Section: Resultsmentioning

confidence: 99%

In vitro evaluation of the amebicidal activity of Pterocaulon polystachyum (Asteraceae) against trophozoites of Acanthamoeba castellanii

et al. 2008

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“…Susceptibility tests in vitro of Acanthamoeba isolates against a number of antimicrobial agents have been reported. Extracts of medicinal plants including Ipomoea sp., Kaempferia galanga, and Cananga odorata showed acanthamoebicidal activities (Chu et al 1998). Several other drugs exhibited amoebicidal or amoebistatic effects against Acanthamoeba trophozoites and cysts in vitro.…”

Section: Discussionmentioning

confidence: 99%

Acanthamoebicidal activity of Fusarium sp. Tlau3, an endophytic fungus from Thunbergia laurifolia Lindl.

et al. 2008

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A fungal endophyte identified as Fusarium sp. Tlau3 was isolated from fresh twig of Thunbergia laurifolia Lindl., a Thai medicinal plant collected from the forest of Chiang Mai Province, Northern Thailand. The fungus was grown on a medium containing yeast extracts and sucrose. The fungal metabolites were isolated from the culture broth by dichloromethane extraction, isooctane/methanol then n-butanol/water partitions, and fractionation with Sephadex LH 20 column chromatography. Acanthamoebicidal fractions were found to induce the formation of large contractile vacuole (LCV) in trophozoites of an Acanthamoeba clinical isolate, leading to cell lysis under isotonic and hypotonic conditions within 1 h. In hypertonic condition, LCV formation was also induced but without cell lysis. Acridine orange staining of the treated cells revealed increased intracellular acidity, implying an increased proton pumping or a vacuolar proton-ATPase (V-ATPase) stimulation. Scanning electron microscopy showed cell membrane damage with intact cytoplasmic organelles. Our finding has indicated that contractile vacuoles of Acanthamoeba trophozoites are the primary target of the amoebicidal substance(s) from this endophytic fungus.

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“…However, conflicting results have been reported. Ketoconazole, pentamidine, hydroxystilbamidine, paromomycin, 5-fluorocytosine, polymyxin, sulfadiazine, trimethoprim-sulfamethoxazole, azithromycin, and extracts of medicinal plants have been indicated as being active against Acanthamoeba in vitro, but no direct evidence has been obtained that these agents are efficacious in individuals with GAE (49,67,82,126,339,377,398,400,401,429,444). Therapeutic agents have also been tested in experimental animals.…”

Section: Treatment Of Acanthamoeba Infections Disseminated Acanthamoementioning

confidence: 99%

Acanthamoebaspp. as Agents of Disease in Humans

2003

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Acanthamoeba spp. are free-living amebae that inhabit a variety of air, soil, and water environments. However, these amebae can also act as opportunistic as well as nonopportunistic pathogens. They are the causative agents of granulomatous amebic encephalitis and amebic keratitis and have been associated with cutaneous lesions and sinusitis. Immuno compromised individuals, including AIDS patients, are particularly susceptible to infections with Acanthamoeba. The immune defense mechanisms that operate against Acanthamoeba have not been well characterized, but it has been proposed that both innate and acquired immunity play a role. The ameba's life cycle includes an active feeding trophozoite stage and a dormant cyst stage. Trophozoites feed on bacteria, yeast, and algae. However, both trophozoites and cysts can retain viable bacteria and may serve as reservoirs for bacteria with human pathogenic potential. Diagnosis of infection includes direct microscopy of wet mounts of cerebrospinal fluid or stained smears of cerebrospinal fluid sediment, light or electron microscopy of tissues, in vitro cultivation of Acanthamoeba, and histological assessment of frozen or paraffin-embedded sections of brain or cutaneous lesion biopsy material. Immunocytochemistry, chemifluorescent dye staining, PCR, and analysis of DNA sequence variation also have been employed for laboratory diagnosis. Treatment of Acanthamoeba infections has met with mixed results. However, chlorhexidine gluconate, alone or in combination with propamidene isethionate, is effective in some patients. Furthermore, effective treatment is complicated since patients may present with underlying disease and Acanthamoeba infection may not be recognized. Since an increase in the number of cases of Acanthamoeba infections has occurred worldwide, these protozoa have become increasingly important as agents of human disease

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Amebicidal activity of plant extracts from Southeast Asia on Acanthamoeba spp.

Cited by 41 publications

References 28 publications

In vitro evaluation of the amebicidal activity of Pterocaulon polystachyum (Asteraceae) against trophozoites of Acanthamoeba castellanii

In vitro evaluation of the amebicidal activity of Pterocaulon polystachyum (Asteraceae) against trophozoites of Acanthamoeba castellanii

Acanthamoebicidal activity of Fusarium sp. Tlau3, an endophytic fungus from Thunbergia laurifolia Lindl.

Acanthamoebaspp. as Agents of Disease in Humans

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