Marine Sponges – Molecular Biology and Biotechnology 8.5 Exploiting the Pharmacological Potential of Marine Sponges 229
Part A | 8.5
in the metagenome of C. concentrica [8.141] and
in the metatranscriptome of G. barretti [8.140], suggesting that symbiotic microbes may be an important source of these essential vitamins for their hosts.
Sponge-associated microbes have also been noted to
be a remarkably rich source of various classes of
chemicals with a wide range of bioactive properties
and are thought to potentially play important roles
in sponge host defence ranging from infection to
predation [8.7].
8.4 Biotechnological Potential of Marine Sponges –
Pharmacological Potential
Much of the recent research interest in the area of marine sponges and marine sponge-associated microbes
has been primarily driven due to the pharmacological potential of many of the diverse chemical entities, with wide ranging biological activities which
have been and continue to be discovered from this
quite unique marine ecosystem [8.149]. The physicochemical properties of the marine environment (pH,
pressure, temperature, osmolarity) in which many marine sponges reside means that any bioactive substances produced in that environment may have sufficiently different properties to terrestrially produced
products to make them of interest for novel drug discovery [8.150]. While the search for novel drugs has
involved many phyla of marine invertebrates, the phylum Porifera has proved to be the most promising
(Fig. 8.4) [8.151]. As previously mentioned, sponges
are sessile filter feeders, with no adaptive immunity,
and thus rely on the production of chemical entities to defend themselves against infection, parasitism,
and disease, and also to gain a competitive advantage [8.150].
Quite a diverse range of chemical classes with
bioactive properties have to date been obtained from
sponges and sponge-derived microbes, and include alcohols [8.152], alkaloids (Table 8.5), amino acid derivatives [8.153–155], aromatic compounds [8.156], fatty
acids [8.157–159], lactones [8.160–162], peptides (Table 8.6), polyacetylenes [8.163, 164], polyketides (Table 8.7), quinones, and quinolones [8.165–168], sphingolipids [8.169, 170], and sterols [8.171–173], together
with terpenes and terpenoids (Table 8.8). These bioactivities have been identified from bacterial or fungal
isolates from sponges or from aqueous or organic extracts from the sponge tissues. In many cases, the
bioactive compounds have been identified, purified, and
characterized.
Numerous compounds and small molecules with activities against important human infections and diseases
have been reported. Important bioactive compounds
which have been reported include antibacterial compounds (including anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) and antituberculosis) (Table 8.4), antifungal compounds (Table 8.5), antiparasitic compounds (including antimalarial) (Tables 8.5–
8.8), antiviral compounds (including anti-HIV) (Tables 8.5, 8.6 and 8.8), anticoagulant compounds [8.174,
175], antihelminthic compounds [8.176], antibiofouling compounds [8.177–179], anti-inflammatory compounds (Tables 8.7 and 8.8), neuromodulatory compounds [8.162, 180, 181], a UV-A protectant compound [8.173], and a large array of cytotoxic compounds with potential uses as anticancer drugs (Tables 8.5–8.8).
8.5 Exploiting the Pharmacological Potential of Marine Sponges
Although many novel bioactive compounds have been,
and continue to be, isolated from sponges and/or their
symbiotic microbes, these compounds are typically produced in minute quantities and the potential utility of
these compounds to the pharmaceutical industry is,
therefore, often somewhat limited [8.231]. For example, when halichondrins were isolated from the marine sponge Halichondria okadai [8.232], they were
identified as very potent antitumor compounds with
enormous clinical potential. However, it was estimated
that 1 t of sponge biomass would need to be harvested
to obtain 300 mg of a mixture of the halichondrin
analogs [8.233]. With 15 kg of the drug being potentially required annually for the treatment of cancer
patients, natural harvest was obviously unrealistic. To
help overcome supply problems such as this, much recent effort has focused on marine products of potential
bacterial origin. Indeed, evidence continues to emerge
Part A | 8.5
in the metagenome of C. concentrica [8.141] and
in the metatranscriptome of G. barretti [8.140], suggesting that symbiotic microbes may be an important source of these essential vitamins for their hosts.
Sponge-associated microbes have also been noted to
be a remarkably rich source of various classes of
chemicals with a wide range of bioactive properties
and are thought to potentially play important roles
in sponge host defence ranging from infection to
predation [8.7].
8.4 Biotechnological Potential of Marine Sponges –
Pharmacological Potential
Much of the recent research interest in the area of marine sponges and marine sponge-associated microbes
has been primarily driven due to the pharmacological potential of many of the diverse chemical entities, with wide ranging biological activities which
have been and continue to be discovered from this
quite unique marine ecosystem [8.149]. The physicochemical properties of the marine environment (pH,
pressure, temperature, osmolarity) in which many marine sponges reside means that any bioactive substances produced in that environment may have sufficiently different properties to terrestrially produced
products to make them of interest for novel drug discovery [8.150]. While the search for novel drugs has
involved many phyla of marine invertebrates, the phylum Porifera has proved to be the most promising
(Fig. 8.4) [8.151]. As previously mentioned, sponges
are sessile filter feeders, with no adaptive immunity,
and thus rely on the production of chemical entities to defend themselves against infection, parasitism,
and disease, and also to gain a competitive advantage [8.150].
Quite a diverse range of chemical classes with
bioactive properties have to date been obtained from
sponges and sponge-derived microbes, and include alcohols [8.152], alkaloids (Table 8.5), amino acid derivatives [8.153–155], aromatic compounds [8.156], fatty
acids [8.157–159], lactones [8.160–162], peptides (Table 8.6), polyacetylenes [8.163, 164], polyketides (Table 8.7), quinones, and quinolones [8.165–168], sphingolipids [8.169, 170], and sterols [8.171–173], together
with terpenes and terpenoids (Table 8.8). These bioactivities have been identified from bacterial or fungal
isolates from sponges or from aqueous or organic extracts from the sponge tissues. In many cases, the
bioactive compounds have been identified, purified, and
characterized.
Numerous compounds and small molecules with activities against important human infections and diseases
have been reported. Important bioactive compounds
which have been reported include antibacterial compounds (including anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) and antituberculosis) (Table 8.4), antifungal compounds (Table 8.5), antiparasitic compounds (including antimalarial) (Tables 8.5–
8.8), antiviral compounds (including anti-HIV) (Tables 8.5, 8.6 and 8.8), anticoagulant compounds [8.174,
175], antihelminthic compounds [8.176], antibiofouling compounds [8.177–179], anti-inflammatory compounds (Tables 8.7 and 8.8), neuromodulatory compounds [8.162, 180, 181], a UV-A protectant compound [8.173], and a large array of cytotoxic compounds with potential uses as anticancer drugs (Tables 8.5–8.8).
8.5 Exploiting the Pharmacological Potential of Marine Sponges
Although many novel bioactive compounds have been,
and continue to be, isolated from sponges and/or their
symbiotic microbes, these compounds are typically produced in minute quantities and the potential utility of
these compounds to the pharmaceutical industry is,
therefore, often somewhat limited [8.231]. For example, when halichondrins were isolated from the marine sponge Halichondria okadai [8.232], they were
identified as very potent antitumor compounds with
enormous clinical potential. However, it was estimated
that 1 t of sponge biomass would need to be harvested
to obtain 300 mg of a mixture of the halichondrin
analogs [8.233]. With 15 kg of the drug being potentially required annually for the treatment of cancer
patients, natural harvest was obviously unrealistic. To
help overcome supply problems such as this, much recent effort has focused on marine products of potential
bacterial origin. Indeed, evidence continues to emerge