Antifungal effect of different methyl and propyl paraben mixtures on the treatment of paper biodeterioration Eva Raquel Neves a , Stephan Scha ¨fer a , Alan Phillips b , Joa ˜o Canejo c , Maria Filomena Macedo a, * a Departamento de Conservaça ˜o e Restauro, Faculdade de Cieˆncias e Tecnologia, Universidade Nova de Lisboa, Monte da Caparica, 2829-516 Caparica, Portugal b Secça ˜o Auto ´noma de Biotecnologia, Faculdade de Cieˆncias e Tecnologia, Universidade Nova de Lisboa, Monte da Caparica, 2829-516 Caparica, Portugal c Departamento de Cie ˆncias dos Materiais, Faculdade de Cieˆncias e Tecnologia, Universidade Nova de Lisboa, Monte da Caparica, 2829-516 Caparica, Portugal article info Article history: Received 18 April 2008 Accepted 7 July 2008 Available online xxx Keywords: Paper Antifungal Parabens Cladosporium Penicillium corylophilum abstract With many important artistic works and documents made of paper, and thus susceptible to biodeteri- oration by fungi, research is required in an effort to replace toxic chemical products with other more benign ones. In this work the antifungal effect of methyl and propyl paraben mixtures at different concentrations was evaluated. The fungi used in the experiments were a Cladosporium species and Penicillium corylophilum, both of which are well known as paper-biodeteriorating fungi. The results demonstrate that a mixture of 0.5% methyl paraben and 1% propyl paraben, in 85% ethanolic solution, is the lowest concentration necessary to provide an efficient antifungal action. A deacidification agent, 5% calcium propionate, was added to this mixture to produce a multi-purpose formulation to treat acidi- fication and fungal contamination of paper documents. Tests carried out on paper samples before and after application of this mixture showed only a minor increase in yellowing and a slight decrease in tensile strength, while substantially raising the pH, and thus the alkaline reserve, and also a slight increase in the percentage of deformation. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Paper is the main material of large artistic and document collections. It is also the most significant carrier of information for many centuries. However, given its organic nature, paper suffers from biodeterioration. Fungi are an almost daily contaminant on paper collections. Infestation is fostered by inadequate storage and display conditions, which allow conidia dispersed in the air to fall on damp and dirty papers (Florian, 1997; Maggi et al., 2000; Lugauskas and Krikstaponis, 2004); mould growth starts when relative humidity and temperature are favourable for spore germination (Caneva et al., 1991). Microfungi are the main micro- organisms responsible for paper biodeterioration (Zyska, 1997, 2002; Adelantado et al., 2005). The activity of fungi on paper can produce several types of damage, such as different coloured stains (Szczepanowska and Lovett, 1992; Aranyanak, 1995; Arai, 2000), discolouration of pigments and inks, and changes in the chemical and physical properties of the paper (Caneva et al., 1991; Nitte ´ rus, 2000). Traditionally, conservators used fungicidal treatments that involved toxic and potentially damaging chemicals to inhibit fungus growth on paper. Some studies propose replacing these traditional antifungal agents with others that are less toxic (Der- sarkissian and Goodberry,1980; Fabbri et al.,1997; Bubiniene ` , 1999; Rakotonirainy et al., 1999; Ricelli et al., 1999; Silva et al., 2006). Nowadays, antifungal agents with low toxicity and high efficacy are already used in the cosmetic, food, and pharmaceutical industries. Parabens (p-hydroxybenzoates) are one of the most common antifungal and preservative agents used in these industries (Ras- togi, 2000; Perlovich et al., 2005; Zhang et al., 2005). Parabens are already largely studied, possess minimal side effects, and have low costs associated with them (Reynolds, 1996; Doron et al., 2001). They are generally used in combination, the most common combination being methyl and propyl parabens (Soni et al., 2005). Paper documents and artistic works containing cellulose also suffer from the acidification process. This is due to the degradation of cellulose that generates aliphatic acids such as acetic, formic, oxalic, and lactic acids, when aging. Nowadays, deacidification treatment is a usual procedure in paper conservation. Manual treatments are normally by baths with aqueous solutions of alka- line salts (calcium or magnesium carbonate or calcium hydroxide) (Dupont et al., 2002; Cheradame et al., 2003; Sundholm and Tah- vanainen, 2003; Zappala ` and Stefani, 2005). However, there are paper documents and artistic works with water susceptible media and inks that make these procedures useless. Therefore it is necessary to improve non-aqueous deacidification treatments. There are some studies that show the possibility of using new * Corresponding author. Tel./fax: þ351 21 294 83 22. E-mail address: mfmd@fct.unl.pt (M.F. Macedo). Contents lists available at ScienceDirect International Biodeterioration & Biodegradation journal homepage: www.elsevier.com/locate/ibiod ARTICLE IN PRESS 0964-8305/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.ibiod.2008.07.011 International Biodeterioration & Biodegradation xxx (2008) 1–6 Please cite this article in press as: Neves E. R., et al., Antifungal effect of different methyl and propyl paraben mixtures on the treatment of..., International Biodeterioration & Biodegradation (2008), doi:10.1016/j.ibiod.2008.07.011