Essential Oils as Natural Biocides in Conservation of Cultural Heritage

Abstract

Essential oils (EOs) have been known for a long time, and they are used in several fields such as medicine and aromatherapy, as well as in the food and pharmaceutical industries. In the last decade, EOs have also been applied to contrast the biodeterioration of cultural heritage, representing a powerful resource in green conservation strategies. In this study, an integrated approach based on microscopic observation, in vitro culture, and molecular investigation was preliminarily employed to identify biological systems colonizing wooden artworks. In order to contrast the biodeterioration processes induced by fungal colonization (Aspergillus flavus) or insect infestation (Anobium punctatum), wooden artworks were exposed to the volatile compound of Origanum vulgare or Thymus vulgaris essential oils (EOs), the chemical composition of which was determined by GC–MS using both polar and apolar columns. Artwork exposure was performed in ad-hoc-assembled “clean chambers.” Evaluating the effects on biological systems, the compatibility with artwork constitutive materials, and the lack of negative effects on human health and environmental pollution, the use of EOs as a valid alternative to traditional biocides must be considered.

Essential Oils Extracted from Different Species of the Lamiaceae Plant Family as Prospective Bioagents against Several Detrimental Pests

“…There is also ongoing progress in the search for pesticidal effects of essential oils extracted from different plant species for pest management strategies [7][8][9][10][11]. Furthermore, essential oils have been assayed as alternatives to commercial pesticides for the green conservation of cultural assets [12,13].…”

The Control of Cultural Heritage Microbial Deterioration

“…The principal chemotypes identified were thymol and carvacrol. Recently, volatile compounds of the same essential oils, O. vulgare and T. vulgari , were used to combat the biodeterioration processes induced by the fungus Aspergillus flavus on wooden artworks [ 88 ]. To this end, the researchers developed ad hoc structures to expose wooden artifacts to the volatile compounds, avoiding any negative impact on the environment and on the operator’s health.…”

Present and Future Perspectives for Biocides and Antifouling Products for Stone-Built Cultural Heritage: Ionic Liquids as a Challenging Alternative

“…There is an increasing interest in the use of natural or biologically derived products that can act as biocides for cultural heritage purposes [33,34].…”

“…• microbial by-products such as zoosteric acid, capsaicin, extracellular enzymes, hydrolases, usnic acid, parietin, or bacterial extract (e.g., Bacillus) [34]; • whole microorganisms against microorganisms [11,35]; • plant extracts such as essential oils [33,36,37], alone or embedded in sol/gel matrix to enhance their performance (Urzì, unpublished data).…”

“…The natural origin of plant extracts as biocides limits their outdoor application. Indoors or in hypogean environments, they have been successfully used to some extent [33]. However, as reported by Fidanza and Caneva, there is a lack of adequate information as to specific efficacy of biodeteriogens at low doses, the durability of the treatment, or eventual interference with material substrates [39].…”