Seasonal Variation in Chemistry and Biological Activity of Monarda fistulosa L

Monarda fistulosa L., also known as wild bergamot or bee balm, is considered a prized medicinal plant by many Native Americans. Referred to as “sweet leaf”, it is one of the Muskogee Seven Sacred Medicines. It is used to treat everything from skin rashes and dermatitis to insect bites and sunburn. This study reports on the chemistry and biological activity of the essential oil and hydroalcoholic extracts obtained from blooming and senescent flower heads and aerial plant parts of Monarda fistulosa. A GC/MS comparison of the blooming and senescent flower essential oils showed increased levels of p-cymene and thymoquinone and decreased levels of thymol and γ-terpinene in the senescent flowers. In addition, the senescent flower essential oil demonstrated stronger anti-inflammatory activity than the other extracts in a 5-lipoxygenase inhibition assay. HPLC analysis also showed differences between the chemistry of non-volatile compounds from hydroalcoholic extracts of the fresh and senescent flowers. Based on traditional use and the positive results of this study, Monarda fistulosa shows promise as a natural ingredient for skin care.