The aim of this study was to assess, using the DPPH assay, the antioxidant activity of several substances that could be proposed to immediately revert the problems caused by bleaching procedures. The percentage of antioxidant activity (AA%) of 10% ascorbic acid solution (AAcidS), 10% ascorbic acid gel (AAcidG), 10% sodium ascorbate solution (SodAsS), 10% sodium ascorbate gel (SodAsG), 10% sodium bicarbonate (Bicarb), Neutralize® (NE), Desensibilize® (DES), catalase C-40 at 10 mg/mL (CAT), 10% alcohol solution of alpha-tocopherol (VitE), Listerine® (LIS), 0.12% chlorhexidine (CHX), Croton Lechleri (CL), 10 % aqueous solution of Uncaria Tomentosa (UT), artificial saliva (ArtS) and 0.05% sodium fluoride (NaF) was assessed in triplicate by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical assay. All substances exhibited antioxidant activity, except for CL. AAcidS, AAcidG and VitE exhibited the highest AA% (p<0.05). On the contrary, CHX, NE, LIS and NaF showed the lowest AA% (p<0.05). In conclusion, AAcidS, AAcidG, SodAsS, SodAsG and VitE presented the highest antioxidant activity among substances tested in this study. The DPPH assay provides an easy and rapid way to evaluate potential antioxidants.

Propolis is a resinous hive product collected by honeybees from various plant sources. It has a complex chemical composition, constituted by various phenolic compounds. Extracts of increasing polarity (n-hexane, chloroform, and ethanol) were obtained from a sample of red propolis from the state of Alagoas. Assays were carried out for determination of contents of phenolics, along with antibacterial and antioxidant activities. The EEP, fractions and sub-fractions showed strong biological activities and were related with phenolic the content compounds contents. The sub-fractions were more bioactive than the EEP and fractions, demonstrating that the antioxidant and antibacterial activities are not a result of synergistic effect between the various chemical compounds in propolis.

Resumen 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 IC₅₀ 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. Se estudio el contenido de compuestos fenólicos, principales flavonoides y la actividad antioxidante de tés procesados e infusiones herbarias. Los compuestos fenólicos totales fueron determinados por el método de Folin-Ciocalteu y variaron desde N.D. hasta 46,46 ± 0,44 mg/g GAE. Los flavonoides fueron investigados por HPLC y la miricetina, quercetina y kaempferol fueron identificados en té negro, verde y en infusión de manzanilla. La actividad antioxidante fue evaluada usando dos metodologías, DPPH y el método de decoloración del μ-caroteno (DBC). Utilizando el DBC, las actividades más elevadas fueron encontradas en las infusiones del té negro, del mate, de la hierba limón, de la manzanilla y del hinojo, mientras que las infusiones herbarias frescas presentaron las actividades más bajas. Utilizando el método de DPPH las infusiones herbarias frescas presentaron las actividades más altas. Las hojas procesadas con los valores más bajos IC₅₀ fueron el té verde y negro (147,63 y 288,60 μg/mL, respectivamente). Los resultados de esta investigación demuestran que las infusiones analizadas son una buena fuente de compuestos que presentan actividad antioxidante in vitro. Palabras clave: Infusión herbaria, té, fenólicos, flavonóides, DPPH, decoloración del β-caroteno