# Antimicrobials from Medicinal Plants: An Emergent Strategy to Control Oral Biofilms
## 6 The Most Promising Medicinal Plant Extracts in the Control of Oral Biofilms
[PERSON] et al. [9] used a chemical fraction of _C. sativum_ essential oil as an antibacterial against _S. mutans_ UA 159, at a concentration of 31.2 mg\(\cdot\)mL\({}^{-1}\), being able to inhibit the growth of _S. mutans_ biofilms by more than 95%. The fatty alcohol 1-decanol is one of the major components found in _C. sativum_ essential oil, and it has been described as an antibacterial and antibiofilm agent [136; 137]. _Copaifera pubiflora_ Benth. is a flowering plant whose oleoresin is widely used in Brazilian medicine due to its anti-inflammatory, analgesic, and antimicrobial properties [138; 139; 140]. In a study performed by [PERSON] et al. [141], oleoresin from _C. pubiflora_ was used as an alternative agent for the removal of oral pathogenic biofilms. This work showed satisfactory data regarding the antimicrobial activity of the used extract against microorganisms normally present in the oral cavity, which included _S. sanguinis_ ATCC 10556 and _P. micra_ clinical isolate (CI), and it was able to eliminate more than 99.9% of preformed biofilms of these species, at a concentration of 50.0 \(\upmu\cdot\)mL\({}^{-1}\). The antimicrobial effect of _C. pubiflora_ oleoresin was attributed to the presence of ent-hardwickitic acid, which was found to be the main compound present in this plant [142]. _Cymbopogon citratus_ (DC.) Stapf, in turn, usually known as lemon grass, is a perennial aromatic plant that is cultivated in tropical and sub-tropical regions [143]. Its essential oil has been found to have many different biological properties, including anxiolytic, antibacterial and antibiofilm incomes [144; 145; 146]. When it comes to oral health, it has been shown that _C. citratus_ exerts an antibiofilm effect on pathogenic bacteria from the oral cavity. As an example, 93.0% of growth inhibition of _S. mutans_ biofilms was obtained at a concentration of 1.00 \(\upmu\cdot\)mL\({}^{-1}\) of _C. citratus_ essential oil [147]. In another study, the essential oil from this plant, at a concentration of 0.100 \(\upmu\cdot\)mL\({}^{-1}\), led to a reduction of more than 95% of _S. mutans_ ATCC 35668 preformed biofilms [148]. In addition, _C. citratus_ oil was tested against _S. mutans_ ATCC 35,688 and _L. acidophilus_ ATCC 4356 single-species biofilms, also inhibiting their growth by more than 95%, although at higher concentrations (26.1 mg\(\cdot\)mL\({}^{-1}\) and 13.2 mg\(\cdot\)mL\({}^{-1}\), respectively). Regarding its chemical composition, the compounds that are usually found in _C. citrattus_ essential oil are citral and myrcene, which are described to have good antimicrobial properties [149]. _Eucalyptus globulus_ Labill is an evergreen tree native to Australia whose leaves have been widely used in pharmaceutical products, given their antimicrobial and antioxidant properties [150]. [PERSON] et al. [151] reported that the _E. globulus_ ethanolic extract exhibited up to 99% eradication activity against _P. gingivalis_ JCM 12257 at a minimum biofilm eradication concentration (MBEC) of 49.1 ug\(\cdot\)mL\({}^{-1}\), and _S. mutans_ NBRC13955 at a MBEC of 393 ug\(\cdot\)mL\({}^{-1}\). The extracts of _Eucalyptus_ species were found to equally contain antimicrobial compounds, such as macrocarpals, eucalyptus and 1,8-cineol [152; 153]. Macrocarpal A, B and C are phloroglucinol derivatives referred to inhibit virulence factors of the periodontopathic bacteria _P. gingivalis_, including specific cysteine proteinases, which appear to be essential for the growth and survival of this bacterium in the periodontal pocket [152]. The presence of specific groups of bioactive compounds can also influence the progression stages of the oral bacterial biofilm's formation. _Derris reticulata_ Craib, a climbing medicinal plant used in folk medicine [154], has prenylated flavanones as its main constituents, whose presence has been linked to several pharmacological outcomes, particularly antibacterial activity [154; 155]. According to [PERSON] et al. [155], the ethanolic extract from stems of _D. reticulata_ was able to inhibit _S.