Antioxidant activity and phenolic composition of herbal infusions consumed in Brazil

Processed tea and herbal infusions were studied for their phenol content, antioxidant activity and main flavonoids. Total phenolics were determined by Folin–Ciocalteu method and ranged from N.D. to 46.46 ± 0.44 mg/g GAE. Flavonoids were investigated by HPLC, and myricetin, quercetin, kaempferol were identified in black, green, and chamomile tea. Antioxidant activity was evaluated using two methods: DPPH and β-carotene bleaching test (BCB). Using the BCB, the highest activities were found for infusions of black tea, mate, lemongrass, chamomile, and fennel; whereas fresh herbal infusions presented the lowest activities. Using the DPPH method, fresh herbal infusions presented the highest activities. Processed leaves with the lowest IC 50 values were green and black tea (147.63 and 288.60 µg/mL, respectively). The results of this research show that the infusions studied are good source of compounds presenting antioxidant activity in vitro.