Bioactivity of oregano methanolic extracts and essential oils is well known. Nonetheless, reports using
aqueous extracts are scarce, mainly decoction or infusion preparations used for therapeutic applications.
Herein, the antioxidant and antibacterial activities, and phenolic compounds of the infusion, decoction
and hydroalcoholic extract of oregano were evaluated and compared. The antioxidant activity is related
with phenolic compounds, mostly flavonoids, since decoction presented the highest concentration of
flavonoids and total phenolic compounds, followed by infusion and hydroalcoholic extract. The samples
were effective against gram-negative and gram-positive bacteria. It is important to address that the hydroalcoholic
extract showed the highest efficacy against Escherichia coli. This study demonstrates that the
decoction could be used for antioxidant purposes, while the hydroalcoholic extract could be incorporated
in formulations for antimicrobial features. Moreover, the use of infusion/decoction can avoid the toxic
effects showed by oregano essential oil, widely reported for its antioxidant and antimicrobial properties.
Foundation for Science and Technology (FCT, Portugal) for N. Martins grant (SFRH/BD/87658/2012), L. Barros researcher contract under “Programa Compromisso com Ciência – 2008” and financial support to the research centre CIMO (strategic project PEst-OE/AGR/UI0690/2011).
