Advances in biological activities of essential oils

Essential oils (EOs), which are secondary metabolites of plants, have volatile and natural characteristics. The biological activities of EOs have been increasing interest for many years, and the number of studies in the literature has increased in parallel with this interest. Although their antimicrobial activities are more common than other biological activities, some areas still need research. In the first stage of this chapter, the known antimicrobial activities of EOs will mainly be evaluated under the titles such as usage of EOs in combinations and encapsulation of EOs. Further, synergistic, additive, or antagonistic interactions of EO combinations will also be associated with their chemical compositions. In the second part, the review will focus on new and remarkable biological activities of EOs such as angiotensin-converting enzyme inhibitory potential, α-amylase and α-glucosidase inhibition potential, and xanthine oxidase inhibition potentials of essential oils. While the antihypertensive activity was correlated with the inhibition of the angiotensin-converting enzyme, antidiabetic activity has been associated with the inhibition of amylase and glucosidase activities. Moreover, inhibition of the xanthine oxidase enzyme prevents overproduction of uric acid and thus hyperuricemia. This situation is associated with antigout activity.