The Potential of and Extracts as Biobased Agents for the Conservation of Cultural Heritage Metals.

BACKGROUND/OBJECTIVES: Biocorrosion, driven by microbial colonization and biofilm formation, poses a significant threat to the integrity of metal artifacts, particularly those composed of copper and its alloys. , a bacterial species that reduces nitrates, plays a key role in this process. This study explores the potential of two metabolite-rich plant extracts, and , as sustainable biobased inhibitors of microbial-induced corrosion (MICOR).

METHODS

The antibacterial and antibiofilm activities of the extracts were evaluated using minimal inhibitory concentration (MIC) assays, time-kill kinetics, and biofilm prevention and removal tests on copper, bronze, and brass samples. Spectrophotometric and microbiological methods were used to quantify bacterial growth and biofilm density.

RESULTS

Both extracts exhibited significant antibacterial activity, with MIC values of 8.3% (/). demonstrated superior bactericidal effects, achieving reductions of ≥3 log in bacterial counts at lower concentrations. In antibiofilm assays, both extracts effectively prevented biofilm formation and reduced established biofilms, with exhibiting greater efficacy against them. The active metabolites-anthraquinones, phenolics, flavonoids, and tannins-likely contribute to these effects.

CONCLUSIONS

These findings highlight the dual role of and extracts as both corrosion and biocorrosion inhibitors. The secondary metabolite profiles of these plants support their application as eco-friendly alternatives in the conservation of metal cultural heritage objects.