208 M.V. Moreno-Arribas et al.
6B.4 Properties of Wine Peptides
Low molecular weight peptides have important functional properties, such as their
tensioactive function and their bioactive properties (antioxidant, antimicrobial, anti-
hypertensive). They are also responsible for sweet and bitter flavors (Polo et al. 2000).
In spite of the importance of the content and structure of food peptides in food
biological activities, in wines they have been very little evaluated apart from their
antihypertensive effects. The increase in hypertension rates in recent years, which
is being considered to be one of the commonest chronic diseases in developed
countries, has favored these types of studies. Most of the antihypertensive peptides
derived from foods act by inhibiting the angiotensin converting enzyme (ACE). This
enzyme is responsible for the increase in blood pressure by converting angiotensin
I into a strong vasoconstrictor, angiotensin II, and by degradation of bradykinin, a
vasodilator. Therefore, ACE inhibition produces a hypotensive effect. More scarce,
however, are studies dealing with the bioactivity of these compounds after ingestion,
since they must be resistant to gastric enzymes and be absorbed in order to produce
a biological effect. Thereby, in spite of the fact that some studies have demonstrated
the in vitro inhibitory effect of some wine peptides on ACE, in vivo studies are
required to demonstrate their true efficacy.
In spite of the lack of studies regarding the antihypertensive effect of wine pep-
tides, in one of them, Takayanagi and Yokotsuka (1999) have determined the ACE
inhibitory activity of two red and four white wines in grapes of the black Muscat
Bailey A variety and in the fermented musts. They demonstrated that red wines
had a higher ACE inhibitory activity than white wines. They also observed that
this activity decreases during fermentation without any clear explanations for this
reduction.
Pozo-Bay ́on et al. (2005) determined the amino acid composition of peptides
from six fractions isolated from red and white wines that presented in vitro antihy-
pertensive activity. They showed that the amino acids aspartic acid and/or asparagine,
glutamic acid and/or glutamine valine, formed part of five of the six fractions stud-
ied, and threonine and alanine were present in four of these fractions.
In long-term studies with normotensive and spontaneously hypertensive rats, it
has been shown (Perrot et al. 2003) that the extract from the low molecular weight
fraction of a Champagne wine had antihypertensive activity in hypertensive rats but
did not affect the normotensive ones. Owing to the complexity of this fraction, the
authors claim that this reduction cannot be attributed only to the presence of a single
compound. Since wine is rich in phenoliccompounds and peptides, both families
of compounds could include individual components with antihypertensive activity
(Ling 2003; Zhang Choi et al. 2003). Pozo-Bay ́on et al. (2005) have demonstrated
the contribution of peptides to this activity. However, they observed a greater ACE
inhibitory activity in red wines, reflecting the possible contribution to the phenolic
compounds. Ling (2003) has shown that phenols can be conjugated with proteins
and produce non-competitive inhibition of the ACE. It is, therefore, necessary to
carry out more studies to identify the compounds responsible for this activity in
wines.