Anti-Bacterial Properties of Cannabigerol Toward Streptococcus mutans

Abstract

Streptococcus mutans (S. mutans) is a gram-positive facultatively anaerobic bacterium and the most common pathogen associated with tooth caries. The organism is acid tolerant and can undergo physiological adaptation to function effectively in acid environments such as carious dental plaque. Some cannabinoids have been found to have potent anti-microbial activity against gram-positive bacteria. One of these is the non-psychoactive, minor phytocannabinoid Cannabigerol (CBG). Here we show that CBG exhibits anti-bacterial activities against S. mutans. CBG halts the proliferation of planktonic growing S. mutans, which is affected by the initial cell density. High-resolution scanning electron microscopy showed that the CBG-treated bacteria become swollen with altered membrane structures. Transmission electron microscopy provided data showing that CBG treatment leads to intracellular accumulation of membrane structures. Nile red, DiOC2(3) and laurdan staining demonstrated that CBG alters the membrane properties, induces membrane hyperpolarization, and decreases the membrane fluidity. CBG-treated bacteria showed increased propidium iodide uptake and reduced calcein AM staining, suggesting that CBG increases the membrane permeability and reduces the metabolic activity. Furthermore, CBG prevented the drop in pH caused by the bacteria. In summary, we present here data showing the mechanisms by which CBG exerts its anti-bacterial effect against S. mutans.

Anti-Biofilm Activity of Cannabigerol against Streptococcus mutans

“…This is demonstrated by the reduced metabolic activity observed after treating preformed biofilms with CBG. Previous data show that CBG induces an immediate membrane hyperpolarization and increases the membrane rigidity, which is followed by an increase in the membrane permeability [34]. These effects of CBG might contribute to the reduced metabolic activity of preformed biofilms.…”

“…The present study shows that the cannabinoid CBG exerts strong anti-biofilm activities towards S. mutans at a concentration as low as 2.5 µg/mL and, thus, is a potential drug in preventing dental caries. The same concentration was found to inhibit the planktonic growth of S. mutans [34], suggesting that some of the effects on biofilm formation is due to its direct anti-bacterial activity. This is demonstrated by the reduced metabolic activity observed after treating preformed biofilms with CBG.…”

“…These effects of CBG might contribute to the reduced metabolic activity of preformed biofilms. CBG also prevented the drop in pH caused by S. mutans that correlated with the reduced bacterial growth [34].…”

“…The glass specimens were washed again with DDW and allowed to dry at room temperature. The specimens were then mounted on a metal stub and sputter coated with iridium and visualized by a highresolution scanning electron microscope (Magellan XHR 400L, FEI Company, Hillsboro, OR) [34]. Three specimens from each treatment group were prepared and examined under SEM to evaluate the effect of CBG on biofilm formation.…”

“…We have demonstrated that CBG has an anti-quorum sensing effect against Vibrio harveyi [33]. Furthermore, we have shown that CBG exerts anti-bacterial effects towards planktonic S. mutans [34]. Here, we tested the potential use of CBG as an anti-biofilm agent against S. mutans biofilms as a mean to combat dental plaque.…”