Overview on Mentha and Thymus Polyphenols

Mentha and Thymus are important genera of the Lamiaceae family widely distributed in the entire World and commonly used in traditional medicine. Indeed, many species of the two genera have been credited with a large list of health-benefit effects, including antioxidant, anti-inflammatory, antimicrobial, analgesic, neuroprotective and anticarcinogenic. In turn, these properties have been associated to the polyphenolic composition of the plants. The present review summarizes the phenolic constituents found in Mentha and Thymus genera, as well as the main methods applied in their extraction, purification and identification. Reported species of Mentha and Thymus usually comprise derivatives of caffeic acid and distinct glycosidic forms of the flavonoids luteolin, apigenin, eriodictyol and naringenin. At present, the phenolic composition of many relevant plants of Mentha and Thymus is still unknown and thus, more studies are required for the adequate phenolic characterization of these two genera. In this context, the present implementation of faster and reliable analytical methodologies, as e.g. the chromatographic techniques hyphenated with mass spectrometry, will surely be an enormous tool in the upgrading of the missing information.