Amoebicidal effects against Acanthamoeba castellanii and DNA-protective activities of natural remedies derived from Turkish medicinal plants

Acanthamoeba infections represent significant public health concerns, particularly Acanthamoeba keratitis (AK) and granulomatous amoebic encephalitis (GAE). Despite chemical-based therapies, these infections often show limited therapeutic success. There is a pressing need for alternative treatments, and medicinal plants have emerged as a promising source of natural therapeutics due to their efficacy and sustainable properties.

Urtica dioica, Hedera helix, and Chenopodium album ethanol extracts were prepared from leaves collected in Ordu, Turkey. Plant material was freeze-dried, ground, and extracted in ethanol, with final extracts adjusted to 45 mg/ml. Various concentrations were tested on Acanthamoeba castellanii trophozoites for 24, 48, and 72 h, assessing viability via Trypan Blue staining. Cytotoxicity was evaluated in HeLa cells using the MTT (3-(4, 5-dimetiltiazol-2-il)-2,5-difeniltetrazolium bromide) assay. DNA protection was tested by incubating plant extracts with pBR322 plasmid DNA, followed by electrophoresis.

The extracts exhibited dose-dependent amoebicidal activity, with IC₅₀ values of 12.5, 28, and 9.8 mg/ml at 72 h, with the highest concentration (45 mg/ml) demonstrating the most substantially effect. Cytotoxicity assays revealed IC₅₀ values of 3.372, 1.735, and 2.417 mg/ml for HeLa cells. Additionally, the plant extracts exhibited protective effects against hydroxyl radical-induced DNA damage in pBR322 plasmid DNA, similar to the DNA-protective agent Torolox. These findings suggest that U. dioica, H. helix, and C. album ethanol extracts have significant potential as therapeutic agents for Acanthamoeba infections and cancer, offering a natural and sustainable alternative.