Phenolic compounds of dark and clear honeys from Trás-os-Montes of Portugal were extracted with
Amberlite XAD-2 and evaluated for their antioxidant and antimicrobial activities. The antioxidant effect
was studied using the in vitro test capacity of scavenge the 2,2-diphenyl-1-picryhydrazyl (DPPH) free
radical and of reducing power of iron (III)/ferricyanide complex. The antimicrobial activity was screened
using three Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus, Staphylococcus lentus) and
three Gram-negative bacteria (Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli). The
results obtained from the partial identification of honey phenolic compounds by high-performance liquid
chromatography with a diode array detector showed that p-hydroxibenzoic acid, cinnamic acid, naringe-
nin, pinocembrin and chrysin are the phenolic compounds present in most of the samples analyzed. Anti-
oxidant potential was dependent of honey extract concentration and the results showed that dark honey
phenolic compounds had higher activity than the obtained from clear honey. In the biological assays,
results showed that S. aureus were the most sensitive microrganisms and B. subtilis, S. lentus, K. pneumo-
niae and E. coli were each moderately sensitive to the antimicrobial activity of honey extracts. Neverthe-
less, no antimicrobial activity was observed in the test with P. aeruginosa.
