Comparative study of antifungal activity of three herbal essential oil of Thymus, Lavender, and Boswellia on paper

Fungi play a significant role in the deterioration of cultural heritage. Due to their high enzyme activity, fungi are able to inhabit and destroy the various materials used for historical objects. Because of the cellulose structure of the paper, paper works in archival documents are very vulnerable to damage by microorganisms, including fungi, and they are always faced with the problem of biodeterioration. Considering the harmful effects of using chemicals on paper works as well as their toxic effect on museum curators and conservators in museum collections and libraries, it is very necessary to find a suitable alternative to deal with destructive fungi. In this regard, the use of herbal essential oils has always been considered. Considering the diversity and abundance of medicinal plants in our country, Iran, in this study, the antifungal effect of the essential oils of three plants including Thymus, Lavender, and Boswellia was evaluated against two common fungal strains isolated from historical documents, including Penicillium and Aspergillus niger. Also, the possible physical and chemical effects of these essential oils on paper were studied to determine which essential oil can be the most suitable option for the decontamination of paper documents.The results obtained in this study confirm that the three investigated essential oils have antifungal activity. But based on the dose required for antimicrobial activity, it can be said that thymus essential oil has more antifungal activity than lavender and Boswellia essential oil. Due to the thymus’s high antimicrobial effect and also the absence of adverse effects on pH and physical properties on paper, it can be a suitable and promising option for protecting paper documents against fungal biodeterioration.