# Antimicrobials from Medicinal Plants: An Emergent Strategy to Control Oral Biofilms
## 6 The Most Promising Medicinal Plant Extracts in the Control of Oral Biofilms
mutans_ biofilms, respectively. Previous reports showed that _Psidium_ sp. and _Mentha_ sp. extracts, as well as their mixtures, have antibacterial and anti-adherence activities against _S. sanguinis_ and _S. mutans_ in single species biofilms [168; 169]. Moreover, the phenolic profile of _Mangifera_ sp. extract revealed that quinic acid, benzophenone _C_-glycosic isomer, benzophenone _C_-glycoside and quercetin-3-_O_-glucose were its main compounds, while in the _Mentha_ sp. extract, methyl 2-[cyclohex-2-en-l-yl(hydroxy)-methyl]-3-hydroxy-4-(2-hydroxyethyl)-3-methyl-5-oxopclimate was mainly found [170], all presenting inhibiting virulence properties of _S. mutans._  
_Myrtus communis_ L. is an important aromatic and medicinal plant species from the Mediterranean area, widely used for culinary, cosmetic, pharmaceutical, therapeutic, and industrial purposes [171]. Antimicrobial and antioxidant proprieties of _M. communis_ have been reported in numerous studies [172]. [PERSON] et al. [173] described the antibiofilm activity of hydroethanolic extracts from its leaves against the oral pathogens _S. mutans_ ATCC 25175, _S. oralis_ (CI), _S. mitis_ (CI), and _R. dentocariosa_ (CI). Curiously, the hydroethanolic extract of _M. communis_ produced a significant (_p_ < 0.05) inhibition in all tested oral pathogens biofilms. MBEC values, assigned to the lowest concentration of each antimicrobial agent that is able to eradicate preformed biofilms, ranged between 40 mg\(\cdot\)mL\({}^{-1}\) (_S. oralis_ and _S. mitis_) and 120 mg\(\cdot\)mL\({}^{-1}\) (_S. mutans_ and _R. dentocariosa_). In a previous study, the same authors were able to identify gallic acid derivatives, tannins, myricetin, and quercetin derivatives as the most abundant phenolic compounds in the hydroalcoholic extract of _M. communis_[174]. The authors also refer that the antibiofilm properties of _M. communis_ have been directly correlated with its phenolic compounds' arrangement. _Rhodiola rosen_ L. is medicinal plant that has been used due to its therapeutic properties and as a potential source of antimicrobial, antioxidant, anti-inflammatory agents, among others [175; 176]. This plant has been recognized to present a broad spectrum of biological activities mainly attributed to its major phytochemical compounds, which include phenylethanes and phenylpropanoids (rosavin, salidoside, rosin, cinnaryl alcohol, and tyrosol) [175; 177]. In a study performed by [PERSON] et al. [178], the _R. rosen_ root ethanolic extract inhibited the biofilm formation of _S. mutans_ UA159 by 95%, at a concentration of 0.50 \(\upmu\)g\(\cdot\)mL\({}^{-1}\), with the highest reduction of EPS synthesis being observed at the same concentration. _R. rosen_ also suppressed the expression of virulence genes and QS system as well as the enzymatic activity of GTF proteins in both 0.25 \(\upmu\)g\(\cdot\)mL\({}^{-1}\) and 0.50 \(\upmu\)g\(\cdot\)ul\({}^{-1}\) concentration groups [178]. At a concentration of 0.12 \(\upmu\)g\(\cdot\)ul\({}^{-1}\), no significant cytotoxic effect was observed, and 0.50 \(\upmu\)g\(\cdot\)ul\({}^{-1}\) and 0.25 \(\upmu\)g\(\cdot\)ul\({}^{-1}\) slightly inhibited the cell proliferation [178]. _Rosmarinus officinalis_ L. is recognized as a fragment medicinal plant, native to the Mediterranean region and cultivated worldwide. In addition to its therapeutic and prophylactic effects, this plant is extensively used as a condition, food preservative and for ornamental purposes [179]. Extensive research has been developed regarding the characterization of the antibiofilm properties of this plant. [PERSON] et al. [151] found that the _R. officinalis_ ethanolic extract was able to eliminate _P. gingivalis_ JCM12257 and _S. mutans_ NBRC13955 biofilm formation at a concentration of 195.5 \(\upmu\)g\(\cdot\)mL\({}^{-1}\) and 97.8 \(\upmu\)g\(\cdot\)mL\({}^{-1}\), respectively. Additionally, the phytochemical profile of this medicinal herb was determined, and it showed that carnsc acid presented the lowest MBEC against _P.