Quantitative Assessment of Antimicrobial Activity of PLGA Films Loaded with 4-Hexylresorcinol

Abstract

Profound screening and evaluation methods for biocide-releasing polymer films are crucial for predicting applicability and therapeutic outcome of these drug delivery systems. For this purpose, we developed an agar overlay assay embedding biopolymer composite films in a seeded microbial lawn. By combining this approach with model-dependent analysis for agar diffusion, antimicrobial potency of the entrapped drug can be calculated in terms of minimum inhibitory concentrations (MICs). Thus, the topical antiseptic 4-hexylresorcinol (4-HR) was incorporated into poly(lactic-co-glycolic acid) (PLGA) films at different loadings up to 3.7 mg/cm2 surface area through a solvent casting technique. The antimicrobial activity of 4-HR released from these composite films was assessed against a panel of Gram-negative and Gram–positive bacteria, yeasts and filamentous fungi by the proposed assay. All the microbial strains tested were susceptible to PLGA-4-HR films with MIC values down to 0.4% (w/w). The presented approach serves as a reliable method in screening and quantifying the antimicrobial activity of polymer composite films. Moreover, 4-HR-loaded PLGA films are a promising biomaterial that may find future application in the biomedical and packaging sector.

Formulation of Antimicrobial Tobramycin Loaded PLGA Nanoparticles via Complexation with AOT

“…Systems that deliver their payloads at a predetermined rate and control the level of active ingredient within target tissues above the minimum effective level for prolonged periods help to reduce the dosing frequency (and concomitantly problems with patient compliance), which offer economic, environmental, health and societal impacts. There is a market need for delivery systems with sustained release of polar antimicrobials capable of eradicating bacterial growth in patients with weak immune systems [62,63,64,65,66,67,68]. Here we describe one method of loading high levels of antimicrobials in PLGA nanoparticles and demonstrate their efficacy against P. aeruginosa in vitro, using transient drug–polymer interactions for encapsulation and slow-release, and we envisage such systems to have potential for the treatment of respiratory infections [69,70].…”

“…There is a market need for the development of drug delivery systems and sustained release of polar antimicrobials capable of eradicating bacterial growth in patients with weak immune system [62,63,64,65,66,67,68]. Here we describe one method of loading high levels of antimicrobials in PLGA nanoparticles and demonstrate their efficacy against P. aeruginosa in vitro, using transient drug-polymer interactions for encapsulation and slow-release.…”

The use of 4-Hexylresorcinol as antibiotic adjuvant

“…4-hexylresorcinol (4-HR) (Fig 1) is a synthetic derivative used as topical drug in antibacterial oral gargles and throat lozenges. [25] Recently, an incorporation of 4-HR within PLGA polymer composite films was proposed as a strategy to obtain biomedical and packaging products with antimicrobial properties. [25] In food industry, 4-HR is frequently used as a preservative and to prevent browning.…”

“…[25] Recently, an incorporation of 4-HR within PLGA polymer composite films was proposed as a strategy to obtain biomedical and packaging products with antimicrobial properties. [25] In food industry, 4-HR is frequently used as a preservative and to prevent browning. [26] The widespread use in food industry and the antiseptic activity of 4-HR give rise to the assumption that 4-HR might be a safe adjuvant for antibiotic combination therapies.…”

Bactericidal activity of hexylresorcinol lozenges against oropharyngeal organisms associated with acute sore throat

“…In vitro studies have found that hexylresorcinol has antibacterial activity against a range of species when in solution and when embedded in biopolymer composite films [18,19]. The antibacterial effects of hexylresorcinol in vivo may be mediated through several mechanisms including reducing bacterial adherence to the pharynx, inhibiting bacterial biofilm formation, disrupting bacterial cell chain formation, and modifying cell surface hydrophobicity [20].…”