Phytochemical Composition, Antioxidant and Antimicrobial Activity of Three Monarda Species: M. bradburiana L. C. Beck, M. × media Willd., and M. punctata L.

Plants of the genus Monarda receive growing interest as the sources of herbal raw materials with wide range of potential applications in food, cosmetics, and phytopharmaceutical industry. This study aimed to evaluate the differences in chemical characteristics and biological activity among different organs of plants representing three underinvestigated species of this genus: Monarda bradburiana L. C. Beck, Monarda × media Willd., and Monarda punctata L. The content of phenolic compounds and the antioxidant activity of leaves, stems, and inflorescences were determined. Essential oil (EO) content, composition, and antimicrobial activity were also examined. M. punctata leaves and inflorescences had the highest EO content (4.43% and 5.59%, respectively), with carvacrol as a dominant constituent. Leaf EO was also rich in thymoquinone (17.48%). In EOs of M. bradburiana and M. × media, thymol dominated. EOs inhibited the growth of all tested strains of microorganisms at a concentration of 0.625 µL × mL-1. The studied plant organs were rich in phenolic compounds, especially rosmarinic acid. M. bradburiana inflorescences were distinguished by high linarin content. Differences in flavonoid distribution seem to have special chemotaxonomic importance. Further research is needed to facilitate standardisation of the investigated plant organs as potential new herbal raw materials.