Medicinal Plants as a Source of New Therapeutic Products: Genus Mentha and the Potential Antimicrobial Activity of Extracts and Essential Oils

The empirical use of plants in the treatment of diseases is a widespread practice since ancient times. Many recent studies concerning plants from genus Mentha, in form of essential oils and extracts, have aimed to show the therapeutic potential of various species found in many regions throughout the world. Particularly, the antimicrobial effects against various infectious agents, like bacteria, fungi and protozoa, have been studied. The aim of this review was to present a comprehensive and detailed investigation of current data on the activity of different species of plants, from the genus Mentha, against various microorganisms that cause human diseases. In this study, different aspects were included such as the region of origin of the researched plants, growing conditions, mode of action and activity of plant compounds, alone or in combination. Although the great potential in the antimicrobial activity of Mentha spp. has been shown, there are important factors that can interfere with the expected therapeutic effects, which need to be better understood. Among these, the growing conditions, species, seasonal aspects and mechanism of extraction of the plants compounds were described. Such factors appear to be decisive for the presence of the therapeutic effect and for the toxicity levels. However, there is still much to clarify about the mechanisms of action of these compounds, their toxicity, mode of action and therapeutic applicability against infections in various sites of the human body.