In vitro amoebicidal effect of Aloe vera ethanol extract and honey against Acanthamoeba spp. cysts.

This study evaluated in vitro effect of different concentrations of Aloe vera (A. vera) ethanol extract and honey against Acanthamoeba spp. cysts in comparison with chlorhexidine (the drug of choice for treatment of Acanthamoeba infection) at different incubation periods. Four different concentrations of the tested agents were used, 100, 200, 400, and 600 µg/ml for A. vera ethanol extract and 25, 50, 100, and 200 µg/ml for honey. Isolated Acanthamoeba spp. cysts from keratitis patients were incubated with different concentrations of the tested agents as well as chlorhexidine 0.02% (drug control) for different incubation periods (24, 48, 72 h). After each incubation period, the effect of A. vera extract and honey against Acanthamoeba cysts was assessed by counting the number of viable cysts, determining the inhibitory percentage and detecting the morphological alternations of treated cysts compared to non-treated and drug controls. Both A. vera ethanol extract and honey showed a concentration and time-dependent effect on the viability of Acanthamoeba cysts. In comparison with chlorhexidine (the drug control), A. vera ethanol extract possessed a potent cysticidal activity at all tested concentrations throughout different incubation periods, except for concentration 100 µg/ml which recorded the lower inhibitory effect. With increasing the dose of A. vera ethanol extract to 200, 400, 600 µg/ml, the recorded inhibitory percentages of Acanthamoeba cysts viability were 82.3%, 92.9% and 97.9% respectively, after 72 h compared to 76.3% of chlorhexidine. Similarly, honey at concentrations of 50-100 µg/ml gave higher inhibitory effect of 59% and 76.7%, respectively compared to chlorhexidine which showed an inhibitory percentage of 55.7% after 24 h. Meanwhile, the lowest tested concentration of honey (25 µg/ml) gave an inhibitory effect by 47.7-67% which was less than that of chlorhexidine throughout different incubation periods. With increasing the dose of honey to 200 µg/ml, the inhibitory effect was 98.9% after 72 h higher than that of chlorhexidine (76.9%). Using a scanning electron microscope, Acanthamoeba cysts treated by A. vera ethanol extract showed alternations in their shapes with flattening, collapsing, and laceration of their walls. Also, treated cysts by honey were highly distorted and difficult to identify because most of them were shrinkage and collapsed to a tiny size. On the other hand, chlorhexidine showed less structural and morphological changes of Acanthamoeba cysts. A. vera ethanol extract and honey had considerable cysticidal effects on Acanthamoeba cysts. They may give promising results for treatment of Acanthamoeba keratitis.

Effects of Thymus vulgaris ethanolic extract on chronic toxoplasmosis in a mouse model.

The current work was undertaken to investigate the potential effectiveness of Thymus vulgaris ethanolic extract (TVE) against Toxoplasma gondii infection in chronic experimental toxoplasmosis. To evaluate prophylactic effects, mice received 500 mg/kg TVE for 5 days before they were infected by an avirulent Me49 T. gondii strain. To investigate the therapeutic effects of the extract postinfection, daily treatment with TVE was initiated at 6 weeks postinfection and continued for 10 days. The following groups of animals were used as controls: uninfected/non-treated, infected/non-treated, and infected/treated with a combination of pyrimethamine and sulfadiazine. Brain cyst count and histopathological changes using H&E and Feulgen stains were used to evaluate the efficacy of TVE. The mean number of brain cysts was significantly decreased by 24 % in mice treated prophylactically with TVE. TVE also significantly reduced the mean number of brain cysts when administered to animals already chronically infected with T. gondii. The effect of TVE was comparable to that of treatment with a mixture of sulfadiazine and pyrimethamine (46 and 51 % reduction, respectively). Moreover, considerable amelioration of the pathological lesions in the brain and retina was observed. The results demonstrate the potential efficacy of T. vulgaris as a new natural therapeutic and prophylactic agent for use in the treatment of chronic toxoplasmosis.

In vitro amoebicidal activity of ethanol extracts of Arachis hypogaea L., Curcuma longa L. and Pancratium maritimum L. on Acanthamoeba castellanii cysts.

Acanthamoeba castellanii causes amoebic keratitis which is a painful sight-threatening disease of the eyes. Its eradication is difficult because the amoebas encyst making it highly resistant to anti-amoebic drugs, but several medicinal plants have proven to be more effective than the usual therapy. This study aimed to evaluate the in vitro amoebicidal activity of ethanol extracts of Arachis hypogaea L. (peanut), Curcuma longa L. (turmeric), and Pancratium maritimum L. (sea daffodil) on A. castellanii cysts. Acanthamoeba were isolated from keratitic patients, cultivated on 1.5% non-nutrient agar, and then incubated with different concentrations of plant extracts which were further evaluated for their cysticidal activity. The results showed that all extracts had significant inhibitory effect on the multiplication of Acanthamoeba cysts as compared to the drug control (chlorhexidine) and non-treated control, and the inhibition was time and dose dependent. The ethanol extract of A. hypogaea had a remarkable cysticidal effect with minimal inhibitory concentration (MIC) of 100 mg/ml in all incubation periods, while the concentrations of 10 and 1 mg/ml were able to completely inhibit growth after 48 and 72 h, respectively. The concentrations 0.1 and 0.01 mg/ml failed to completely inhibit the cyst growth, but showed growth reduction by 64.4-82.6% in all incubation periods. C. longa had a MIC of 1 g and 100 mg/ml after 48 and 72 h, respectively, while the concentrations 10, 1, and 0.1 mg/ml caused growth reduction by 60-90.3% in all incubation periods. P. maritimum had a MIC of 200 mg/ml after 72 h, while the 20-, 2-, 0.2-, and 0.02-mg/ml concentrations showed growth reduction by 34-94.3% in all incubation periods. All extracts seemed to be more effective than chlorhexidine which caused only growth reduction by 55.3-80.2% in all incubation periods and failed to completely inhibit the cyst growth. In conclusion, ethanol extracts of A. hypogaea, C. longa, and P. maritimum could be considered a new natural agent against the Acanthamoeba cyst.