4. Conclusions
The EO of the E. calycina presented a high yield and,
predominantly, consisted of sesquiterpene compounds. Fractionation
enabled the separation of oxygenated and non-oxygenated
sesquiterpenes. The antimicrobial activity against oral bacteria
showed that the EO obtained high activity against anaerobic Gramnegative
bacteria P. nigrescens and P. gingivalis, and moderate or no
activity for other bacteria. This observation was similar for fraction
F1, which contained sesquiterpene hydrocarbon. Therefore,
the properties of these compounds can be determinants of the
action of the oil against the tested bacteria. F3 and F4, composed
of oxygenated sequiterpenes, showed high activity for all bacteria,
except A. naeslundii. The EO and its fractions indicated a higher
selectivity against oral bacteria and lower toxicity towards HeLa
cells when the growth of the microorganisms was inhibited at low
concentrations. Thus, the high yield of the EO and the results of
antimicrobial activity found for E. calycina make it promising for
the treatment of oral bacteria.