Evaluation of Biosynthesized Berberis vulgaris-loaded gold nanocomposites: in vitro cytotoxicity and anti-giardial efficacy against giardia intestinalis

Giardiasis is a common parasitic disease that remains a major global health concern, largely because of rising drug resistance and the adverse effects linked to existing therapeutic options. To address this urgent need for novel therapeutic strategies, we explored the potential of Berberis vulgaris, a traditionally recognized medicinal plant, and its biosynthesized gold nanocomposites (BV-AuNPs) as anti-giardial agents. Initially, a comprehensive phytochemical characterization of B. vulgaris root bark was performed, revealing a diverse spectrum of bioactive constituents, including phenolic compounds, flavonoids, and various volatile metabolites, which likely contribute to its established traditional medicinal applications. We then successfully developed BV-AuNPs using an environmentally friendly green synthesis approach. Our characterization studies, employing UV-Vis, FT-IR, and TEM, confirmed the successful formation of stable, predominantly spherical gold nanoparticles with an average size of 10 nm, indicating the plant extract’s role in both reduction and stabilization. In our in vitro assessments, we observed that BV-AuNPs exhibited significantly enhanced antioxidant activity compared to the raw B. vulgaris extract. More critically, we evaluated their anti-giardial efficacy against Giardia intestinalis. Both the B. vulgaris extract and BV-AuNPs demonstrated dose-dependent mortality against G. intestinalis cysts and trophozoites. Notably, BV-AuNPs consistently showed superior efficacy, achieving 96.41% cyst mortality and 93.2% trophozoite mortality at 150 µg/mL, comparable to the efficacy of metronidazole at a much lower concentration (25 µg/mL). Furthermore, we extended our evaluation to an in vivo murine model. Here, BV-AuNPs significantly reduced fecal cyst counts by 72.2% and intestinal trophozoite load by an impressive 90%, surpassing the efficacy of the raw extract and demonstrating strong therapeutic potential. Our results demonstrate that the nano-formulation markedly enhances the anti-giardial activity of B. vulgaris, likely through improved bioavailability and targeted delivery of its bioactive compounds. These findings provide a foundation for developing a more effective and safer therapeutic strategy for giardiasis.