Investigating the biological properties of carbohydrate derived fulvic acid (CHD-FA) as a potential novel therapy for the management of oral biofilm infections.
BACKGROUND
A number of oral diseases, including periodontitis, derive from microbial biofilms and are associated with increased antimicrobial resistance. Despite the widespread use of mouthwashes being used as adjunctive measures to control these biofilms, their prolonged use is not recommended due to various side effects. Therefore, alternative broad-spectrum antimicrobials that minimise these effects are highly sought after. Carbohydrate derived fulvic acid (CHD-FA) is an organic acid which has previously demonstrated to be microbiocidal against Candida albicans biofilms, therefore, the aims of this study were to evaluate the antibacterial activity of CHD-FA against orally derived biofilms and to investigate adjunctive biological effects.


METHODS
Minimum inhibitory concentrations were evaluated for CHD-FA and chlorhexidine (CHX) against a range of oral bacteria using standardised microdilution testing for planktonic and sessile. Scanning electron microscopy was also employed to visualise changes in oral biofilms after antimicrobial treatment. Cytotoxicity of these compounds was assessed against oral epithelial cells, and the effect of CHD-FA on host inflammatory markers was assessed by measuring mRNA and protein expression.


RESULTS
CHD-FA was highly active against all of the oral bacteria tested, including Porphyromonas gingivalis, with a sessile minimum inhibitory concentration of 0.5%. This concentration was shown to kill multi-species biofilms by approximately 90%, levels comparable to that of chlorhexidine (CHX). In a mammalian cell culture model, pretreatment of epithelial cells with buffered CHD-FA was shown to significantly down-regulate key inflammatory mediators, including interleukin-8 (IL-8), after stimulation with a multi-species biofilm.


CONCLUSIONS
Overall, CHD-FA was shown to possess broad-spectrum antibacterial activity, with a supplementary function of being able to down-regulate inflammation. These properties offer an attractive spectrum of function from a naturally derived compound, which could be used as an alternative topical treatment strategy for oral biofilm diseases. Further studies in vitro and in vivo are required to determine the precise mechanism by which CHD-FA modulates the host immune response.
Infection and Immunity Research Group, Glasgow Dental School, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, 378 Sauchiehall Street, Glasgow G2 3JZ, UK. gordon.ramage@glasgow.ac.uk.
Leighann
L
Sherry
Emma
E
Millhouse
David F
DF
Lappin
Colin
C
Murray
Shauna
S
Culshaw
Christopher J
CJ
Nile
Gordon
G
Ramage
D000704:Analysis of Variance; D001419:Bacteria / Q000187:drug effects*; D001578:Benzopyrans / Q000494:pharmacology* / Q000627:therapeutic use* / Q000633:toxicity; D018441:Biofilms / Q000187:drug effects*; D002461:Cell Line, Transformed / Q000187:drug effects; D002710:Chlorhexidine / Q000494:pharmacology / Q000627:therapeutic use; D015169:Colony Count, Microbial; D003773:Dental Plaque / Q000188:drug therapy*; D015536:Down-Regulation; D004847:Epithelial Cells / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D056747:Immunomodulation; D018836:Inflammation Mediators; D016209:Interleukin-8 / Q000096:biosynthesis; D010518:Periodontitis / Q000188:drug therapy / Q000382:microbiology; D018709:Statistics, Nonparametric
D001578:Benzopyrans; D018836:Inflammation Mediators; D016209:Interleukin-8; D002710:Chlorhexidine; C005023:fulvic acid