Phenolic acids content and antioxidant capacity of commercially available Melissa officinalis L. teas in Bulgaria

The Lemon balm (Melissa officinalis L.) is an important aromatic and medicinal plant from Lamiaceae family. Its leaves and essentials oils are used in folk medicine for the treatment of fevers and colds, hyperthyroidism, headaches and toothaches. Melissa officinalis is a rich source of volatile oil, flavonoid glycosides and derivatives of caffeic acid (rosmarinic acid). The aim of current study was to evaluate and compare the polyphenol content and antioxidant activity of infusions prepared from commercially available lemon balm brands on Bulgarian market. The total polyphenol content was established to be in range from 18.17 +/- 0.04 to 64.17 +/- 0.52 mg GAE/g dw, the total derivatives of caffeic acid from 3.80 +/- 0.05 to 21.66 +/- 0.10 mg CAE/g dw, caffeic acid content from 0.16 +/- 0.01 to 0.97 +/- 0.03 mg/g dw and rosmarinic acid between 2.4 +/- 0.02 and 23.1 +/- 0.5 mg/g dw, respectively. In vitro radical scavenging activity was evaluated by DPPH method (106.31 +/- 9.87 - 553.51 +/- 46.04 mM TE/g dw) and the metal reducing antioxidant potential was established by CUPRAC method (321.32 +/- 14.39 - 1476.63 +/- 11.32 mM TE/g dw). As a result the consumption of M. officinalis infusions could be recommended as a good preventive and therapeutic source of biologically active substances with potential benefit effects.