1 2 Antimicrobial, antiviral and antioxidant activities of ‘‘água-mel’’ fr Q1 om Portugal 3 Maria G. Miguel a,⇑ Q2 , Leonor Faleiro b , Maria D. Antunes a , Smail Aazza a , Joana Duarte b , Ana R. Silvério b 4 a Universidade do Algarve, IBB-Centro de Biotecnologia Vegetal, Faculdade de Ciências e Tecnologia, Edif. 8, Campus de Gambelas, 8005-139 Faro, Portugal 5 b Universidade do Algarve, IBB-Centro de Biomedicina Molecular e Estrutural, Faculdade de Ciências e Tecnologia, Edif. 8, Campus de Gambelas, 8005-139 Faro, Portugal 6 7 9 article info 10 Article history: 11 Received 24 November 2012 12 Accepted 4 February 2013 13 Available online xxxx 14 Keywords: 15 ‘‘Água-mel’’ 16 Phenols 17 Melanoidins 18 Biological properties 19 20 abstract 21 ‘‘Água-mel’’ is a honey-based product produced in Portugal for ancient times. Several attributes have 22 been reported to ‘‘água-mel’’ particularly in the alleviation of simple symptoms of upper respiratory tract. 23 Samples of ‘‘água-mel’’ from diverse beekeepers from different regions of Portugal were studied in what 24 concerns antimicrobial, antioxidant and antiviral properties. The amounts of phenol and brown pigment 25 were also evaluated and correlated with the antioxidant activities. A great variability on the levels of 26 these compounds was found among samples which were responsible for the variability detected also 27 on the antioxidant activities, independent on the method used. Generally, antioxidant activity correlated 28 better with brown pigments’ amount than with phenols’ content. The antimicrobial activity found for 29 ‘‘água-mel’’ samples confirm the virtues reported by popular findings. In addition, this work also reveals 30 the antiviral properties of ‘‘água-mel’’ evidenced by a decrease on the infectivity of the Qb bacteriophage. 31 Ó 2013 Elsevier Ltd. All rights reserved. 32 33 34 35 1. Introduction 36 A non-enzymatic reaction which occurs during baking, roasting, 37 broiling, and frying of food is responsible for the formation of fla- 38 vour compounds and brown pigments. For example, heat treatment 39 of food is used extensively to increase the palatability of food. The 40 brown pigments have a relative high impact on the quality of foods, 41 because the colour is a key factor in consumer acceptance. This 42 brown colour is attributed to the reaction between reducing carbo- 43 hydrates and amino acids or proteins, known as Maillard reaction. 44 During this reaction, there is the formation of a complex mix of di- 45 verse components of different molecular weights, including alde- 46 hydes, ketones, dicarbonyls, acryl amides, heterocyclic amines (all 47 of them contributing to flavour), melanoidins and advanced glyca- 48 tion endproducts (AGEs) (both being polymeric products formed at 49 the advanced steps of Maillard reaction) (Wang et al., 2011). Mela- 50 noidins are coloured compounds reported as possessing antioxi- 51 dant activity and other biological properties. According to a 52 recent review made by Wang et al. (2011), melanoidins present 53 capacity for scavenging free radicals and chelating metal ions in 54 in vitro assays. In vivo studies have revealed that a food melanoidin 55 containing pyrrolinone reductonyl-lysine present in bread crust, 56 caraffa malt, or pronyl bovine serum albumin decreased oxidative 57 stress and thiobarbituric acid reactive substances levels, and in- 58 creased tocopherol in the plasma of rats (Somoza et al., 2005). Anti- 59 microbial activity has been also described for melanoidins and they 60 can act as bacteriostatic or bactericidal, depending on the concen- 61 trations. At low concentrations, melanoidins exert a bacteriostatic 62 activity by the chelation of iron from the culture medium and at 63 high concentrations they are bactericidal by chelating magnesium 64 ions from the outer membrane, leading to a destabilization of the 65 inner membrane with the consequent release of intracellular mol- 66 ecules (Rufian-Henares and de la Cueva, 2009). 67 Honey is a source of high concentrations of reducing sugars 68 (glucose and fructose), also possessing free aminoacids and pro- 69 teins. The presence of these components is responsible for the 70 non-enzymatic browning commonly observed during prolonged 71 storage of honey, as well as when it is submitted to heating. The 72 formation of these brown pigments generally coincides with an in- 73 crease of antioxidant and antimicrobial activities (Brudzynski and 74 Kim, 2011, 2011a,b; Turkmen et al., 2006a,b). The high molecular 75 weight melanoidins were already recognised by Brudzynski and 76 Miotto (2011a,b) as being the main components responsible for 77 radical-scavenging ability of Canadian honeys. 78 A honey-based product known as ‘‘água-mel’’ is produced in 79 Portugal for ancient times. This product also produced in Sardinia 80 region (Italy) (Spano et al., 2008) is obtained from honeycombs 81 which still possessing residues of honey are crumbled and dipped 82 into warm water for separating waxes which are removed carefully 83 from the top. The remaining mixture (water, honey, pollen and 84 some propolis) is submitted to heat, until obtaining a brown, hon- 0278-6915/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fct.2013.02.007 Abbreviations: AAPH, 2,2 0 -Azobis-2-methyl-propanimidamide, dihydrochloride; ABTS, 2,2 0 -azino-bis(3-ethylbenzothiazoline-6-sulphonic acid; AGEs, glycation end- products; AU, absorption units; AUC, area under the curve; FL, fluorescein; ORAC, oxygen radical activity capacity; PFU, plaque-forming unit. ⇑ Corresponding author. Tel.: +351 289800900; fax: +351 289818419. E-mail address: mgmiguel@ualg.pt (M.G. Miguel). Food and Chemical Toxicology xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Food and Chemical Toxicology journal homepage: www.elsevier.com/locate/foodchemtox FCT 7144 No. of Pages 9, Model 5G 23 February 2013 Please cite this article in press as: Miguel, M.G., et al. Antimicrobial, antiviral and antioxidant activities of ‘‘água-mel’’ fr Q1 om Portugal. Food Chem. Toxicol. (2013), http://dx.doi.org/10.1016/j.fct.2013.02.007