In vitro activity of some natural honeys against Entamoeba histolytica and Giardia lamblia trophozoites

Considering the potentiality of honey in combating diseases, the present study was carried out aiming to assess the in vitro antiprotozoal activity of several honeys (Ziziphus spina-christi, Acacia nilotica, Acacia seyal, and Cucurbita maxima) against Entamoeba histolytica and Giardia lamblia by employing the sub-culture method. All the tested honeys inhibited the growth of trophozoites, and the level of inhibition varied according to the assayed concentrations and incubation times. Acacia seyal honey had completely stopped motility of E. histolytica trophozoites at a concentration ≤ 50 µg/ml after incubation for 72 h. Ziziphus spina-christi, Acacia seyal, and Acacia nilotica honeys had completely inhibited the growth of Giardia lamblia trophozoites at concentration ≤ 200 µg/ml after 72 h. These inhibitory activities were similar to that of Metronidazole™ which showed IC₅₀ = 0.27. The mammalian cytotoxicity of these honeys against normal Vero cell line which determined by applying MTT method verified the nontoxicity of the examined honeys. Also the proximate composition of the samples indicated compliance with the natural honey standards. The findings of the study indicate the need for in vivo studies and further investigations to identify active principles with antiprotozoal activities from natural honeys.