Contents lists available at ScienceDirect Trends in Food Science & Technology journal homepage: www.elsevier.com/locate/tifs Review Impact of curcumin nanoformulation on its antimicrobial activity Anderson Clayton da Silva a , Priscila Dayane de Freitas Santos a , Jéssica Thais do Prado Silva a , Fernanda Vitória Leimann a , Lívia Bracht b , Odinei Hess Gonçalves a,* a Post-Graduation Program of Food Technology (PPGTA), Federal University of Technology - Paraná, Via Rosalina Maria dos Santos, 1233, Postal Code 87301-899, Campo Mourão, Brazil b Biochemistry Department, Maringá State University, Av. Colombo, 5.790, Postal Code 87020-900, Maringá, Brazil ARTICLE INFO Keywords: Curcuma longa Encapsulation Nanonization ABSTRACT Background: Curcumin is a yellow-orange, hydrophobic compound extracted from Curcuma longa and widely used by oriental cultures. It displays numerous biological activities and shows antimicrobial activity against both Gram-positive and Gram-negative bacteria, as well as yeasts and molds. However, its low water solubility de- creases its bioavailability and hinders its industrial use. Curcumin may be modified by micro/nanoencapsulation or nanonization (transformation in nanometric crystals) techniques, to improve its water solubility and dis- persibility and potentiate its biological properties. Furthermore, encapsulated curcumin may be applied to foods as a preservative, to increase the product's shelf life. Scope and approach: In this work, the recent developments in the antimicrobial activity of micro- and nano- formulations (nano/microparticles, capsules and nanocrystals) of curcumin are comprehensively reviewed. Also, the most common methods applied for antimicrobial determination are listed and discussed, highlighting the conflicting results of inhibitory concentration that may be found by each technique. Key findings and conclusions: When evaluating the antimicrobial properties of curcumin, it becomes important to determine the actual gains from encapsulation because these techniques are usually expensive and may lead to the degradation of curcumin during the encapsulation steps. Attention must be paid when choosing the most suitable experimental method to determine the antimicrobial activity of encapsulated curcumin because minimum inhibitory concentration values may vary significantly. 1. Introduction Curcumin is the main product from extraction of Curcuma longa rhizome, being widely used by Asian pharmacology and medicine (particularly in China and India), due to its various biological activities and intrinsic low toxicity (Deshpande et al., 1998; Kumavat et al., 2013; Qureshi, Shah, & Ageel, 1992; Shlar et al., 2015). Commercial extracts typically contain a mixture of curcuminoid derivatives, and typical values are 5.69–2.86% curcumin, 1.47% demethoxycurcumin and 1.36% bisdemethoxycurcumin (Li, Yuan, Deng, Wang, & Yang, 2011) (Fig. 1). Studies of curcumin have demonstrated diverse biological properties, such as antiproliferative (Dubey, Sharma, Narain, Misra, & Pati, 2008) and chemopreventive (Duvoix et al., 2005)effects, cyto- toxicity to certain cell lines (Lal, Gupta, Thavaselvam, & Agarwal, 2013), anti-inflammatory (Rocha et al., 2014), antioxidant (Carvalho, Takeuchi, Geraldine, Moura, Célia, et al., 2015), antimutagenic (Fernández-Bedmar & Alonso-Moraga, 2016), anti-amyloid (Mathew et al., 2012), wound healing (Krausz et al., 2015), neuroprotective (Mythri & Bharath, 2012), biofilm formation inhibition (Hu, Huang, & Chen, 2013) and antimicrobial activity (suitable references are given later). However, the practical applications of curcumin are often limited by its low water solubility and sensitivity to alkaline conditions, heat, light, metal ions, enzymes, oxygen and ascorbic acid, among others (Paradkar, Ambike, Jadhav, & Mahadik, 2004; Paramera, Konteles, & Karathanos, 2011). In this sense, curcumin is a promising candidate for the development of new natural materials, such as micro/nanoparticles and nanocrystals, to enhance its stability against aforementioned fac- tors and harness biological properties (Shlar et al., 2015; Wang, Tan, Zhong, Chen, & Wang, 2011). The antimicrobial property of curcumin is well-known and the mechanism involves the interaction with the essential cell division in- itiating protein FtsZ. The bacterial cytoskeleton is necessary for growth and cellular division, while the FtsZ protein is involved in bacterial cell https://doi.org/10.1016/j.tifs.2017.12.004 Received 25 January 2017; Received in revised form 22 November 2017; Accepted 9 December 2017 * Corresponding author. E-mail addresses: andersonclayton19@hotmail.com.br (A.C.d. Silva), pri_day13@hotmail.com (P.D.d.F. Santos), jessicathais92@gmail.com (J.T.d.P. Silva), fernandaleimann@utfpr.edu.br (F.V. Leimann), lbracht@gmail.com (L. Bracht), odinei@utfpr.edu.br (O.H. Gonçalves). Trends in Food Science & Technology 72 (2018) 74–82 Available online 14 December 2017 0924-2244/ © 2017 Elsevier Ltd. All rights reserved. T