HPLC–DAD–ESI–MS analysis of the constituents of aqueous preparations of verbena and lemon verbena and evaluation of the antioxidant activity

Verbena and lemon verbena aqueous preparations were investigated for their content of constituents, especially polyphenols by HPLC/DAD/ESI/MS analysis because they are used worldwide as herbal teas. The main class of compounds of these plants were phenylpropanoids (from 16 to 120 mg/g of dried extract), being verbascoside the most abundant in all the preparations up to 97% of the total phenylpropanoids. Also iridoids, hastatoside and verbenalin together with flavonoids, mono- and di-glucuronidic derivatives of luteolin and apigenin were found. These simple preparations, especially that obtained from infusion of lemon verbena, could be lyophilized to obtain a powder having interesting technological properties to be used as ingredients of cosmetics, food supplements and herbal medicinal products do to the many biological properties of verbascoside. In addition, the antioxidant property of the lemon verbena infusion was evaluated by the DPPH test using Trolox as the reference compound.