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Poly(anhydride-esters) comprised exclusively of naturally occurring antimicrobials and EDTA: antioxidant and antibacterial activities.

Carbone-Howell AL, Stebbins ND, Uhrich KE - Biomacromolecules (2014)

Bottom Line: The resulting polymers were characterized to confirm their chemical composition and understand their thermal properties and molecular weight.In vitro release studies demonstrated that polymer hydrolytic degradation was complete after 16 days, resulting in the release of free antimicrobials and EDTA.Antioxidant and antibacterial assays determined that polymer release media exhibited bioactivity similar to that of free compound, demonstrating that polymer incorporation and subsequent release had no effect on activity.

View Article: PubMed Central - PubMed

ABSTRACT
Carvacrol, thymol, and eugenol are naturally occurring phenolic compounds known to possess antimicrobial activity against a range of bacteria, as well as antioxidant activity. Biodegradable poly(anhydride-esters) composed of an ethylenediaminetetraacetic acid (EDTA) backbone and antimicrobial pendant groups (i.e., carvacrol, thymol, or eugenol) were synthesized via solution polymerization. The resulting polymers were characterized to confirm their chemical composition and understand their thermal properties and molecular weight. In vitro release studies demonstrated that polymer hydrolytic degradation was complete after 16 days, resulting in the release of free antimicrobials and EDTA. Antioxidant and antibacterial assays determined that polymer release media exhibited bioactivity similar to that of free compound, demonstrating that polymer incorporation and subsequent release had no effect on activity. These polymers completely degrade into components that are biologically relevant and have the capability to promote preservation of consumer products in the food and personal care industries via antimicrobial and antioxidant pathways.

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Disk diffusion assayresults for E. coli (A) and S. aureus (B) showing zonesof growth inhibition for 1:1 PBS/DMSO (a), extracted eugenol (b),extracted thymol (c), extracted carvacrol (d), free eugenol (e), freethymol (f), free carvacrol (g), and EDTA (h).
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fig5: Disk diffusion assayresults for E. coli (A) and S. aureus (B) showing zonesof growth inhibition for 1:1 PBS/DMSO (a), extracted eugenol (b),extracted thymol (c), extracted carvacrol (d), free eugenol (e), freethymol (f), free carvacrol (g), and EDTA (h).

Mentions: To ensure that polymer degradationproducts diffusing from the discs would cause clear zones of growthinhibition, the polymer was completely hydrolyzed and a specific bioactiveconcentration was prepared from extracted products and compared tothat of equivalent concentrations of free bioactives; the concentrationfor all bioactives was kept at 10 mg/mL (greater than the minimuminhibitory concentrations (MICs) to ensure a clear zone is observed)in 1:1 PBS/DMSO. S. aureus, a Gram-positivebacterium, and E. coli, a Gram-negativebacterium, were both evaluated, since both strains are commonly encounteredand often responsible for contamination of products leading to spoilage.38 As shown in Figure 5,the free phenols diffused from the discs and prevented bacterial growthon the agar. Both the free bioactives (e−g) and the extractedbioactives (b–d) exhibited nearly the same zones of inhibitionfor both strains (Table 1). Neither EDTA (h)nor PBS/DMSO (a) controls exhibited any activity against either strain.Carvacrol and thymol displayed greater activity compared to eugenol,which is expected owing to eugenol’s higher MICs against bothstrains.6 Overall, this assay shows thatthe methods used to process the bioactives used did not alter theirantibacterial activity upon release from polymer.


Poly(anhydride-esters) comprised exclusively of naturally occurring antimicrobials and EDTA: antioxidant and antibacterial activities.

Carbone-Howell AL, Stebbins ND, Uhrich KE - Biomacromolecules (2014)

Disk diffusion assayresults for E. coli (A) and S. aureus (B) showing zonesof growth inhibition for 1:1 PBS/DMSO (a), extracted eugenol (b),extracted thymol (c), extracted carvacrol (d), free eugenol (e), freethymol (f), free carvacrol (g), and EDTA (h).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4020595&req=5

fig5: Disk diffusion assayresults for E. coli (A) and S. aureus (B) showing zonesof growth inhibition for 1:1 PBS/DMSO (a), extracted eugenol (b),extracted thymol (c), extracted carvacrol (d), free eugenol (e), freethymol (f), free carvacrol (g), and EDTA (h).
Mentions: To ensure that polymer degradationproducts diffusing from the discs would cause clear zones of growthinhibition, the polymer was completely hydrolyzed and a specific bioactiveconcentration was prepared from extracted products and compared tothat of equivalent concentrations of free bioactives; the concentrationfor all bioactives was kept at 10 mg/mL (greater than the minimuminhibitory concentrations (MICs) to ensure a clear zone is observed)in 1:1 PBS/DMSO. S. aureus, a Gram-positivebacterium, and E. coli, a Gram-negativebacterium, were both evaluated, since both strains are commonly encounteredand often responsible for contamination of products leading to spoilage.38 As shown in Figure 5,the free phenols diffused from the discs and prevented bacterial growthon the agar. Both the free bioactives (e−g) and the extractedbioactives (b–d) exhibited nearly the same zones of inhibitionfor both strains (Table 1). Neither EDTA (h)nor PBS/DMSO (a) controls exhibited any activity against either strain.Carvacrol and thymol displayed greater activity compared to eugenol,which is expected owing to eugenol’s higher MICs against bothstrains.6 Overall, this assay shows thatthe methods used to process the bioactives used did not alter theirantibacterial activity upon release from polymer.

Bottom Line: The resulting polymers were characterized to confirm their chemical composition and understand their thermal properties and molecular weight.In vitro release studies demonstrated that polymer hydrolytic degradation was complete after 16 days, resulting in the release of free antimicrobials and EDTA.Antioxidant and antibacterial assays determined that polymer release media exhibited bioactivity similar to that of free compound, demonstrating that polymer incorporation and subsequent release had no effect on activity.

View Article: PubMed Central - PubMed

ABSTRACT
Carvacrol, thymol, and eugenol are naturally occurring phenolic compounds known to possess antimicrobial activity against a range of bacteria, as well as antioxidant activity. Biodegradable poly(anhydride-esters) composed of an ethylenediaminetetraacetic acid (EDTA) backbone and antimicrobial pendant groups (i.e., carvacrol, thymol, or eugenol) were synthesized via solution polymerization. The resulting polymers were characterized to confirm their chemical composition and understand their thermal properties and molecular weight. In vitro release studies demonstrated that polymer hydrolytic degradation was complete after 16 days, resulting in the release of free antimicrobials and EDTA. Antioxidant and antibacterial assays determined that polymer release media exhibited bioactivity similar to that of free compound, demonstrating that polymer incorporation and subsequent release had no effect on activity. These polymers completely degrade into components that are biologically relevant and have the capability to promote preservation of consumer products in the food and personal care industries via antimicrobial and antioxidant pathways.

Show MeSH