10.7 Applications
227
they can manifest the antihypertensive bioactivity. This is usually achieved artificially
through enzymatic hydrolysis, heat treatment or fermentation. This could possibly
happen naturally in the body and perhaps why the seaweeds have been associated
with such properties when consumed as foods (Sabirin et al. 2016).
Proteins and peptides are susceptible to enzymatic breakdown in the gastrointestinal tract. Orally consumed peptides may therefore not have sufficient bioactivity
to elicit their antihypertensive effect when taken into the body through this route.
The peptides’ bioactivity is highly dependent on the sequence of amino acid and
the primary and secondary structures of the short chain (usually 2–20 amino acid
residues). When taken orally, these are susceptible to being digested as other food
proteins and broken down and absorbed into the body as amino acids. Therefore, for
these peptides to be able to elicit antihypertensive effect, they need to either have
resistance to the enzymes within the gastrointestinal tract, completely bypass the
gastrointestinal tract by using other routes of delivery into the bloodstream or be
prepared in forms which protects the active ingredient (in this case the polypeptide)
until it gets to the target.
On the other hand, the intestinal enzyme activity could act on these peptides and
convert them to more active antihypertensive short-chain peptides. This has been
demonstrated in peptides extracted from Ulva rigida, where the peptides containing
three amino acid residues produced from the hydrolysis of the parent protein were
further broken down by the intestinal mucosa peptidase into a smaller peptide containing two amino acid residues (Paiva et al. 2016). In this case, the intestinal enzyme
activity was beneficial in improving the antihypertensive effect of the peptides by
partial digestion.
Indeed, the studies on the antihypertensive effect of these algae-derived peptides
are relatively advanced and have been carried out on animal and human test subjects
(Saito et al. 2002; Saito and Hagino 2005). Algae species from which peptides have
been shown to have antihypertensive activity have been extracted that include U.
pinnatifida, Porphyra yezoensis and U. rigida (Seca and Pinto 2018).
The presence of particular groups such as D-amino acids thiophene oxazole and
some alpha and beta amino acids within the polypeptide structures of some marine
plants gives them some excellent bioactive properties. Some products also exist in the
market as functional foods with antihypertensive effects. Examples are Evolus® and
Ameal-S 120® (Seca and Pinto 2018). The potency of the different peptides varies,
and the hypertensive effect is also dose dependent. Example prescribed dosage is
1.8 g daily of Pyropia yezoensis-derived peptides to human patients (Saito et al.
2002) and 10 mg per day per kg of body weight to hypertensive rats through oral
administration (Suetsuna and Nakano 2000).
10.7.6 Antioxidant
Compounds which inhibit the activities of reactive oxygen species or remove them for
the body are referred to as antioxidants (Yucetepe et al. 2018). Algae and other aquatic
227
they can manifest the antihypertensive bioactivity. This is usually achieved artificially
through enzymatic hydrolysis, heat treatment or fermentation. This could possibly
happen naturally in the body and perhaps why the seaweeds have been associated
with such properties when consumed as foods (Sabirin et al. 2016).
Proteins and peptides are susceptible to enzymatic breakdown in the gastrointestinal tract. Orally consumed peptides may therefore not have sufficient bioactivity
to elicit their antihypertensive effect when taken into the body through this route.
The peptides’ bioactivity is highly dependent on the sequence of amino acid and
the primary and secondary structures of the short chain (usually 2–20 amino acid
residues). When taken orally, these are susceptible to being digested as other food
proteins and broken down and absorbed into the body as amino acids. Therefore, for
these peptides to be able to elicit antihypertensive effect, they need to either have
resistance to the enzymes within the gastrointestinal tract, completely bypass the
gastrointestinal tract by using other routes of delivery into the bloodstream or be
prepared in forms which protects the active ingredient (in this case the polypeptide)
until it gets to the target.
On the other hand, the intestinal enzyme activity could act on these peptides and
convert them to more active antihypertensive short-chain peptides. This has been
demonstrated in peptides extracted from Ulva rigida, where the peptides containing
three amino acid residues produced from the hydrolysis of the parent protein were
further broken down by the intestinal mucosa peptidase into a smaller peptide containing two amino acid residues (Paiva et al. 2016). In this case, the intestinal enzyme
activity was beneficial in improving the antihypertensive effect of the peptides by
partial digestion.
Indeed, the studies on the antihypertensive effect of these algae-derived peptides
are relatively advanced and have been carried out on animal and human test subjects
(Saito et al. 2002; Saito and Hagino 2005). Algae species from which peptides have
been shown to have antihypertensive activity have been extracted that include U.
pinnatifida, Porphyra yezoensis and U. rigida (Seca and Pinto 2018).
The presence of particular groups such as D-amino acids thiophene oxazole and
some alpha and beta amino acids within the polypeptide structures of some marine
plants gives them some excellent bioactive properties. Some products also exist in the
market as functional foods with antihypertensive effects. Examples are Evolus® and
Ameal-S 120® (Seca and Pinto 2018). The potency of the different peptides varies,
and the hypertensive effect is also dose dependent. Example prescribed dosage is
1.8 g daily of Pyropia yezoensis-derived peptides to human patients (Saito et al.
2002) and 10 mg per day per kg of body weight to hypertensive rats through oral
administration (Suetsuna and Nakano 2000).
10.7.6 Antioxidant
Compounds which inhibit the activities of reactive oxygen species or remove them for
the body are referred to as antioxidants (Yucetepe et al. 2018). Algae and other aquatic