Novel aqueous oil-in-water emulsions containing extracts of natural coniferous resins are strongly antimicrobial against enterobacteria, staphylococci and yeasts, as well as on bacterial biofilms

Abstract

Aims: The aim of this study was to examine the antimicrobial properties of novel aqueous natural rapeseed oil/saline emulsions containing different soluble components of spruce resin. Methods and Results: The composition of aqueous resin emulsions was analysed by GC-MS and their antimicrobial properties were studied with challenge tests and with turbidometric assays. The emulsions were strongly antimicrobial against common Gram-positive and Gram-negative bacteria (including MRSA) as well as common yeasts. Furthermore, they inhibited the biofilm formation and eradicated the microbial biofilms on tested microbes. Characteristic for the emulsions was the presence of oxidized resin acids. Other main components present in emulsions, such as lignans and coumaric acids, were not antimicrobial, when tested separately. Conclusions:The results indicated that the oxidized resin acids were the antimicrobial components in the emulsions. Also, there appears to be a stoichiometric relationship between the number of resin acid molecules and the number microbe cells in the antimicrobial action. Significance and Impact of the Study: The fact that these solutions do not contain abietic acid, which is the main allergenic compound in resins, suggests that these solutions would be suitable, well-tolerated antimicrobials for various medical applications. The aqueous formulation will also allow the expansion of the use of these emulsions in from medical applications to the food preservatives and disinfectants. IntroductionCreams or salves based on natural resins collected from trunks ("callus" resin) of Norway spruce (Picea abies), have been used as home-made remedies for skin wounds and infections for hundreds of years (Cowan 1999;Kalemba and Kunicka 2003;Mahady 2005;Rautio et al. 2007;Sipponen 2013). The water-insoluble main resin acids (e.g. abietic acids or dehydroabietic acid) in coniferous resins have been shown to be antimicrobial and antifungal in several previous studies (S€ oderberg et al. 1990;Savluchinske Feio et al. 1999;Rautio et al. 2007Rautio et al. , 2012Sipponen and Laitinen 2011). However, the poor solubility in water limits their applicability as microbicidal agents, or as modern liquid antiseptics (Peng and Roberts 2000;Keeling and Bohlmann 2006).A novel method to disperse the partially soluble components of natural coniferous resins into water makes the manufacturing of aqueous resin emulsions possible. However, this might lead to the loss antimicrobial properties due to the exclusion of resin acids. In this study, we examined the retained antimicrobial activities of two 136

Bactericidal efficiency of preparation based on essential oils used in aerosol disinfection in the presence of poultry

“…Thus, the action of ultraviolet light to enhance the bactericidal action of bioaerosol without the addition of disinfectant substances was insufficient for reliable disinfection, but the addition of titanium dioxide (TiO 2 P25) and zinc oxide (ZnO) significantly increased the effectiveness of the aerosol (Rodrigues-Silva et al, 2017). These are the essential oils that guarantee high activity of complex preparations against grampositive and gram-negative bacteria, multi-resistant forms of pathogens (MRSA), biofilms, and yeast (Haapakorva et al, 2018). Complexes of metal nanoparticles with essential oils are promising disinfectants and bactericides.…”

Antimicrobial properties of rosin acids-loaded nanoparticles against antibiotic-sensitive and antibiotic-resistant foodborne pathogens

“…To reduce cytotoxicity of RA-NPs, structural modification of RA can be undertaken with view of improving on their safety [11]. Furthermore, acute toxicity tests on mice would Data are reported as average ± standard deviation among different strains for each species.…”

“…Despite the potential of RA as antimicrobials, intrinsic hydrophobicity makes their use as modern aqueous-based antiseptics difficult [9][10][11]. Furthermore, when incorporated in high doses, RA are known to exert topical toxic effects [12].…”

“…Furthermore, when incorporated in high doses, RA are known to exert topical toxic effects [12]. Recent attempts to increase the solubility of rosinic acids in water have been conducted by preparing aqueous oil-in-water emulsions [11], with substantial antimicrobial effects against bacteria and yeasts, including methicillin-resistant S. aureus.…”

Pinoresinol stimulates keratinocyte proliferation and downregulates TNF‐α secretion in peripheral blood mononuclear cells: An experimental in vitro study

“…Shortly, callus resin collected from trunks of Norway spruce ( P. abies ) was dissolved in RY, glycerol (GLY), or 1,3‐propanediol (DI) and transferred further to saline to reach a stable oil‐in‐water emulsion. 2 RO was prepared similarly by using the tall oil rosin instead of the “callus” resin. These dispersions were used at various dilutions in the experiments.…”