Cinnamaldehydes potential inhibitory effect towards planktonic and biofilm of oral bacteria

Oral biofilms act as the mediator for caries. Biofilm was formed from interaction between bacteria which was known as polymicrobial. The defense system of polymicrobial was difficult to penetrate by antibiotic. The discovery of new candidate for polymicrobial biofilms can be essential challenge to be studied. The purpose of this study was to investigate antibacterial and antibiofilm activity of cinnamaldehyde on monospecies and polymicrobial oral biofilms including Streptococcus sanguinis, Streptococcus mutans, Lactobacillus acidophilus and Actinomyces viscosus. Antibacterial was conducted with microdilution method. Antibiofilm assay consisted of biofilm inhibition formation and biofilm degradation in intermediate phase and mature phase. A minimum biofilm inhibition concentration (MBIC<inf>50</inf>) which caused 50 inhibition and a minimum biofilm eradication concentration (MBEC<inf>50</inf>) which caused 50 degradation were tested using crystal violet and read on a microplate reader 595 nm wavelength. A Confocal Laser Scanning Electron Microscope (CLSM) were used to study biofilm cell viability. Cinnamaldehyde showed antibacterial effect against S. sanguinis, S. mutans, L. acidophilus and A. viscosus, as well as inhibitory effect against A. viscosus in intermediate phase and degradation effect against S. sanguinis, S. mutans, L. acidophilus and A. viscosus in intermediate phase and mature phase. The result of CLSM indicated that the number of viable bacteria (green colonies) after treatment with cinnamaldehyde was less than the number of viable bacteria in the negative control both in monospecies and polymicrobial biofilms tested. Based on the result, the study can be concluded that cinnamaldehyde had antibacterial and antibiofilm activity on monospecies and polymicrobial biofilms. © 2020 Elsevier B.V., All rights reserved.