Dissertação mest., Engenharia Biológica, Universidade do Algarve, 2009In this work it was determined the antioxidant, neuroprotective and anti-hyperglycemic
activity of methanol (MeOH), hexane and water extracts made from two species of
Mediterranean oaks, Quercus suber L. (cork oak) and Quercus ilex L. (holm oak), and
Ceratonia siliqua L. (carob tree). Additionally, a phytochemical evaluation was made.
The extracts were made from different organs or products namely leaves, fruits, pulps,
germ flour, gum and stem bark from carob tree and leaves and acorns from Quercus
species. Samples were collected from mature trees growing in the Algarve. Acorns from
cork oak were also sampled in Alentejo, to check for the influence of geographic origin
on the biological activities of the extracts. Moreover, a thermal treatment (‘dry
roasting’) at 200 ºC was applied to a part of the acorn samples, and compared to the
results obtained in samples dried at 50 ºC. The chemical profile varied in all the
parameters, the MeOH extracts were richer in phenolic compounds, which were present
in higher amounts in leaves (Quercus species), and in leaves and stem bark (carob tree).
Acorns had a considerable amount of phenolics and lipids. There was a great variation
in the major compound between samples. Methanol extracts from leaves, acorns and
stem bark exhibited an interesting antioxidant activity. The leaf extracts from the two
species had a high inhibitory activity against acetylcholinesterase and
butyrylcholinesterase. The extracts had no relevant activity against α-amylase, but a
potent inhibitory activity on α-glucosidase from baker’s yeast. Altogether, these results
indicate that leaves and stem bark from carob tree, and acorns from cork oak and holm
oak have bioactive compounds useful in the prevention/treatment of the above
mentioned disorders. Further research is needed in order to identify the bioactive
compounds, trough a bio-guided fractioning of the extracts
