The aquatic environment, such as oceans, rivers, or lakes, is rich in biodiversity:
fishes, marine sponges, jellyfishes, molluscs, crustaceans, or algae, among
many others (including a huge and mostly unknown multiplicity of microorganisms).
This variety turns out to be a gold mine in terms of natural biopolymers
diversity. The exploitation of marine compounds for biological and biomedical
applications is an area being explored more intensely in the latest years, in order
to take advantage of all these abundant and underexplored marine resources. The
idea is the valorization of underexplored marine organisms, such as seaweeds,
or of by-products as consequence of the activity of fish processing industries.
This involves, for instance, marine organisms that are caught by mistake on sea
net fishes (by-catches) and are not used for food purpose, or fish processing byproducts
from industries. Indeed, ~75% of fish weight is discarded as processing
leftovers such as skins, bones, fins, heads, guts, and scales, from which arises a
huge potential for conversion into valuable products. Those natural polymers can
be classified into proteins (collagen, gelatin, keratin, etc.), polysaccharides (agar,
alginate, carrageenan, chitin, fucoidan, chondroitin sulfate, hyaluronic acid, etc.),
and nucleic acids. Also bioceramics (hydroxyapatite, biosilica, calcium carbonates,
etc.) take part in the constitution of some marine organisms (Ratner et al.
2004). Recent researches have arisen with the successful development of methods
for isolation, purification, and characterization of these compounds from several
marine sources, envisaging their application in many different industrial fields
(Percival 1979; Nagai et al. 1999; Nagai and Suzuki 2000; Kinoshita-Toyoda et al.
2004; Abdou et al. 2008; Li et al. 2008).
A significant issue that has been under discussion lately when considering the use
of natural polymers in health is the risk of posing diseases from animals to humans.
In particular, bovine and porcine origins are common sources used to isolate natural
polymers, and these have that inherent risk of transmitting diseases, such as bovine
spongiform encephalopathy, to humans, a disease that attacked a huge area worldwide.
Moreover, there are the constraints regarding some consumers due to their
religious beliefs (halal and kosher markets). In this way, marine biopolymers can
overcome such issues, because there is, until now, no evidence of disease risk from
marine organisms to humans; therefore, they can be consumed by everyone, despite
religious beliefs.
In this context, biopolymers from marine origin have gained an increased
interest in the market of different fields. Paul Scheuer (University of Hawaii)
was the first chemist to study marine natural products in 1950s until his death in
2003. With this starting research on marine toxin structures, other works in this
area led to the discovery of biologically active molecules, which had potential
to be used in human pharmaceutical agents. A high importance has been given
to pharmaceutical science for drug delivery purposes, because there are several
compounds with different bioactivities, including antitumor capacity, which
will be soon discovered. For instance, extracted marine bioactive peptides have
shown several biological functions such as anticancer, antihypertensive, antioxidative,
antimicrobial, antithrombotic, antihypercholesterol, immunomodulatory,
prebiotic, opioid agonistic, and mineral-binding activities, without the potential
side effects of the developed synthetic drugs (Kim et al. 2013). Other potential
applications have arisen in others fields, with the evolution of extraction, purification,
and processing techniques. For example, improvement in solubility of
marine food proteins is explored so they can be used as food supplements, along
with chemical and enzymatic modifications. Natural bioactive compounds are
mostly required for beauty purposes, which are used to maintain a young appearance
with the use of new cosmetics. So, there is an increasing need of using
natural products, which are safe and inexpensive ingredients, so far. With this
growing interest, it is very likely that the use of by-products to extract marine
compounds is instilling a new commercial value to them. Regarding this, the
valorization of by-products can be exploited for this purpose, giving them a new
meaning with great economic and environmental advantages (Dutta et al. 2004; Silva et al. 2012).