The wood, bark, and leaves of Quercus species (Fagaceae)
are rich sources of ellagitannins and condensed tannins.
The aqueous extract of Quercus coccifera L. was reported
to show potent antimicrobial activity against Streptococcus
aureus, though no active principles were assigned.1 The
outer bark of Quercus suber L., which is a common tree of
the Mediterranean region, is well known as a material of
stoppers and corkboards used for insulation. The occurrence
of triterpenoids,2,3 lignins,4 tannins,4 and phenylpropanoids,5
besides the major component, suberin, in the
cork was reported. However, the tannins and related
polyphenols of the leaves of the above two plants have been
little investigated. This paper deals with the isolation and
structural elucidation of five new hydrolyzable tannins
from the leaves of Q. coccifera and Q. suber.