Melissa officinalis L. (lemon balm) is normally consumed as infusions and presents therapeutic properties such as sedative, carminative and antispasmodic, being also included in some pharmaceutical preparations. The phenolic profiles of different samples of lemon balm prepared as infusions were evaluated by HPLC-DAD-ESI/MS. The profiles were compared in order to understand the differences between cultivated, in-vitro cultured and commercial (bags and granulated) samples. All the samples showed a similar phenolic profile, presenting differences only in the quantities found of each compound. Rosmarinic acid was the most abundant compound, being higher in commercial samples, especially in tea bag sample (55.68 mg/g of infusion) and lower in in-vitro cultured sample (15.46 mg/g). Moreover, dimers, trimers and tetramers of caffeic acid were identified and quantified for the first time in lemon balm. Only one flavonoid, luteolin-3’-O-glucuronide was found in all the samples, ranging from 8.43 mg/g in commercial granulate sample to 1.22 mg/g in in-vitro cultured sample. Overall, cultivated and in-vitro cultured samples presented the lowest amounts of phenolic compounds (59.59 and 30.21 mg/g, respectively); otherwise, commercial samples showed the highest contents (109.24 mg/g for tea bag and 101.03 mg/g for granulate sample). The present study shows that infusion of lemon balm can be a source of phenolic compounds, known for their bioactive effects.
PEst-OE/AGR/UI0690/2011 for financial support to CIMO. L. Barros thanks to FCT, POPH-QREN and FSE for her grant (SFRH/BPD/4609/2008). The GIP-USAL is financially supported by the Consolider-Ingenio 2010 Programme (FUN-C-FOOD, CSD2007-00063). M. Dueñas thanks the Spanish “Ramón y Cajal”
