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Anti‐ Acanthamoeba Activities of Silica Nanoformulated Quercetin Compound Derived From Annona muricata L. Leaves

Year: 2026

Type: article

Abstract: Acanthamoeba spp., free‐living amoebae (FLA), are the causative agents of Acanthamoeba keratitis (AK) and granulomatous amoebic encephalitis (GAE). These diseases have limited treatment options; therefore, drug discovery remains a critical priority. This study evaluated the leaf extract of Annona muricata L., which contains quercetin, formulated in silica nanoparticles against Acanthamoeba species. The anti‐ Acanthamoeba effect of the nanoformulation was determined by its MIC and percentage viability. Scanning electron microscopy confirmed the nanocompound‐directed effect on trophozoites and cysts. The nanoquercetin exhibited anti‐ Acanthamoeba activity, showing greater effectiveness against the trophozoites of Acanthamoeba polyphaga ATCC 30461 (AP) (MIC > 2 mg/mL) compared to cysts (MIC > 8 mg/mL) and against A. triangularis WU19001 (AT) trophozoites (MIC > 4 mg/mL) compared to cysts (MIC > 8 mg/mL). It also showed reduced activity against Acanthamoeba castellanii ATCC 30010 (AC3) trophozoites (MIC > 4 mg/mL) compared to cysts (MIC > 8 mg/mL) and A. castellanii ATCC50739 (AC5) trophozoites (MIC > 4 mg/mL) compared to cysts (MIC > 8 mg/mL). The anti‐ Acanthamoeba activity of A. muricata on all four species was compared to chlorhexidine, which had MIC values of 0.008 mg/mL for AC3 and AT trophozoites and 0.016 mg/mL for AC5 and AP trophozoites. For cysts, chlorhexidine exhibited MIC values of > 0.0128 mg/mL for AC3 and AP, 0.032 mg/mL for AC5, and 0.064 mg/mL for AT. All MIC values demonstrated inhibition of Acanthamoeba species with reduced viability exceeding 90%. SEM findings revealed morphological changes in Acanthamoeba , indicating parasitic inhibition. Quercetin‐loaded silica nanoparticles demonstrated anti‐ Acanthamoeba activity with low cytotoxicity. This indicates the potential of quercetin as a nano‐enhanced natural therapeutic or contact lens‐care agent. This study is limited by its in vitro design, small parasite strain panel, and potential nanoparticle variability. This highlights the need for in vivo validation, ocular/contact lens model testing, and formulation optimization for improved cysticidal efficacy.

Source: Scientifica

DOI: 10.1155/sci5/5902580