Anti-Giardia Activity of Pistacia atlantica Hydroalcoholic Extract Against Giardia lamblia Cysts

Giardiasis is a globally common protozoan disease with significant public health impact, causing diarrhea, nausea, weight loss, bloating, and abdominal pain. Current treatments face limitations including drug resistance and adverse effects, highlighting the need for alternative therapeutic agents. This study evaluated the cysticidal effects of hydroalcoholic extracts from the fruits and leaves of Pistacia atlantica subsp. Kurdica against Giardia lamblia cysts in vitro.

G. lamblia cysts (1 × 10⁴/mL) were exposed to five concentrations of leaf and fruit extracts (0.25-4 mg/mL) for 12, 24, and 48 h at 37 °C. Saline buffer was the negative control and metronidazole (0.25-4 μg/mL) the positive control. Cyst viability was assessed by 0.1% eosin exclusion staining. All assays were performed in triplicate.

The leaf extract demonstrated significant concentration- and time-dependent cysticidal activity at all time points (P < 0.05), reaching 70-80% cyst mortality at 2-4 mg/mL after 48 h. The 0.25 mg/mL concentration showed no significant effect at 12 h (P > 0.05). The fruit extract showed no cysticidal activity at any concentration or time point (P > 0.05). Metronidazole was potent at all concentrations and time points (P < 0.0001), with the leaf extract showing comparable efficacy (P > 0.05).

The leaf extract of P. atlantica exhibited significant in vitro cysticidal activity against G. lamblia in a concentration- and time-dependent manner, comparable to metronidazole, while the fruit extract showed no activity. Further studies on trophozoite stages, phytochemical characterization, cytotoxicity, and animal models are needed before therapeutic conclusions can be drawn.