title: Chitosan-propolis nanoparticle formulation demonstrates anti-bacterial activity against Enterococcus faecalis biofilms.
abstract: Propolis obtained from bee hives is a natural substance with antimicrobial properties. It is limited by its insolubility in aqueous solutions; hence ethanol and ethyl acetate extracts of Malaysian propolis were prepared. Both the extracts displayed antimicrobial and anti-biofilm properties against Enterococcus faecalis, a common bacterium associated with hospital-acquired infections. High performance liquid chromatography (HPLC) analysis of propolis revealed the presence of flavonoids like kaempferol and pinocembrin. This study investigated the role of propolis developed into nanoparticles with chitosan for its antimicrobial and anti-biofilm properties against E. faecalis. Bacteria that grow in a slimy layer of biofilm are resistant to penetration by antibacterial agents. The use of nanoparticles in medicine has received attention recently due to better bioavailability, enhanced penetrative capacity and improved efficacy. A chitosan-propolis nanoformulation was chosen based on ideal physicochemical properties such as particle size, zeta potential, polydispersity index, encapsulation efficiency and the rate of release of the active ingredients. This formulation inhibited E. faecalis biofilm formation and reduced the number of bacteria in the biofilm by ~90% at 200 μg/ml concentration. When tested on pre-formed biofilms, the formulation reduced bacterial number in the biofilm by ~40% and ~75% at 200 and 300 μg/ml, respectively. The formulation not only reduced bacterial numbers, but also physically disrupted the biofilm structure as observed by scanning electron microscopy. Treatment of biofilms with chitosan-propolis nanoparticles altered the expression of biofilm-associated genes in E. faecalis. The results of this study revealed that chitosan-propolis nanoformulation can be deemed as a potential anti-biofilm agent in resisting infections involving biofilm formation like chronic wounds and surgical site infections.
authors.affiliation: School of Postgraduate Studies, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia.
authors.forename: Teik Hwa
authors.initials: TH
authors.lastname: Ong
authors.affiliation: Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia.
authors.forename: Ebenezer
authors.initials: E
authors.lastname: Chitra
authors.affiliation: Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia.
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Ramamurthy
authors.affiliation: Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia.
authors.forename: Rajinikanth Paruvathanahalli
authors.initials: RP
authors.lastname: Siddalingam
authors.affiliation: School of Pharmaceutical Sciences, Universiti Sains Malaysia, Gelugor, Penang, Malaysia.
authors.forename: Kah Hay
authors.initials: KH
authors.lastname: Yuen
authors.affiliation: Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia.
authors.forename: Stephen Periathamby
authors.initials: SP
authors.lastname: Ambu
authors.affiliation: Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia.
authors.forename: Fabian
authors.identifier: http://orcid.org/0000-0001-7297-5948
authors.initials: F
authors.lastname: Davamani
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects; D048271:Chitosan / Q000737:chemistry*; D013293:Enterococcus faecalis / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D011429:Propolis / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D011429:Propolis; D048271:Chitosan