337
macroalgae also showed antimicrobial activity. The red alga Sphaerococcus coronopifolius and the green alga Codium iyengarii showed antibacterial activity, while
another green alga, Ulva fasciata, showed antiviral activity by virtue of a novel
sphingosine it produced (Ali et al. 2002). Antiviral properties of polysaccharides
extracted from seaweeds were documented in late 1950s. It was observed that algaederived polysaccharides were able to inhibit mumps and influenza B viruses (Gerber
et al. 1958). The next two decades were eventful and more polysaccharide fractions
from red algae were reported to have activities against herpes simplex virus (HSV)
and other viruses (Deig et al. 1974). Compounds such as dictyota diterpenes isolated from brown alga Dictyota menstrualis, griffithsin from the red alga Griffithsin
sp., and sulfated polymannuroguluronate (SPMG) from the brown alga Laminaria
aponica showed inhibition or deactivation of Human Immunodeficiency Virus
(HIV) (Meiyu et al. 2003; Pereira et al. 2004; De Souza et al. 2005). The mechanism
of action of SPMG is identified; it binds to the trans-activating protein of HIV (Tat)
and thereby interferes with the entry of the virus to host T lymphocytes. This compound is under the phase II clinical trials in China (Wu et al. 2011). Various other
alga-derived compounds show antifungal and antiparasitic activities (Torres et al.
2014; Yu et al. 2014).
Sea grasses are marine flowering plants growing anchored in the sand or mud of
shallow areas of the sea. There are about 60 species of sea grasses identified so far.
The secondary metabolites they produce are believed to be part of their defense
mechanism. Many of these compounds have therapeutic importance
(Athiperumalsamii et al. 2008). Cymodocea spp. is used to treat diseases like cough
and malaria, while Halophila spp. is found to be used to cure malaria and certain
skin diseases. Latter is effective to treat leprosy in the early stages (Yuvaraj et al.
2012). The true therapeutic potential of compounds from sea grasses is only being
discovered.
13.7.2 Marine Fauna
Bioactive compounds from marine fauna have been used as antimicrobials from
olden times. Therapeutically important compounds are isolated mainly from invertebrates such as sponges, cnidarians, annelids, arthopods, molluscs, etc. Major
classes of marine animal derived compounds are steroids, terpenoids, isoprenoids,
nonisoprenoids, quinones, brominated compounds, nitrogen heterocyclics, nitrogen
sulfur heterocyclics, etc. They are used as natural molecules or as synthetically
modified compounds. These compounds are used against various pathogenic microorganisms including bacteria, virus, fungi, protozoan, helminthic parasites, etc.
(Bhakuni and Rawat 2006).
Sponges are very simple, cellular grade (no organized tissues) multicellular
organisms found in aquatic habitats. They are the richest source of bioactive compounds in the marine environment. These compounds are generally the secondary
metabolites originated from sponges and their symbionts by the action of functional
enzyme clusters (Laport et al. 2009; Sagar et al. 2010). Sponges alone produce more
13 Novel Sources of Antimicrobials
macroalgae also showed antimicrobial activity. The red alga Sphaerococcus coronopifolius and the green alga Codium iyengarii showed antibacterial activity, while
another green alga, Ulva fasciata, showed antiviral activity by virtue of a novel
sphingosine it produced (Ali et al. 2002). Antiviral properties of polysaccharides
extracted from seaweeds were documented in late 1950s. It was observed that algaederived polysaccharides were able to inhibit mumps and influenza B viruses (Gerber
et al. 1958). The next two decades were eventful and more polysaccharide fractions
from red algae were reported to have activities against herpes simplex virus (HSV)
and other viruses (Deig et al. 1974). Compounds such as dictyota diterpenes isolated from brown alga Dictyota menstrualis, griffithsin from the red alga Griffithsin
sp., and sulfated polymannuroguluronate (SPMG) from the brown alga Laminaria
aponica showed inhibition or deactivation of Human Immunodeficiency Virus
(HIV) (Meiyu et al. 2003; Pereira et al. 2004; De Souza et al. 2005). The mechanism
of action of SPMG is identified; it binds to the trans-activating protein of HIV (Tat)
and thereby interferes with the entry of the virus to host T lymphocytes. This compound is under the phase II clinical trials in China (Wu et al. 2011). Various other
alga-derived compounds show antifungal and antiparasitic activities (Torres et al.
2014; Yu et al. 2014).
Sea grasses are marine flowering plants growing anchored in the sand or mud of
shallow areas of the sea. There are about 60 species of sea grasses identified so far.
The secondary metabolites they produce are believed to be part of their defense
mechanism. Many of these compounds have therapeutic importance
(Athiperumalsamii et al. 2008). Cymodocea spp. is used to treat diseases like cough
and malaria, while Halophila spp. is found to be used to cure malaria and certain
skin diseases. Latter is effective to treat leprosy in the early stages (Yuvaraj et al.
2012). The true therapeutic potential of compounds from sea grasses is only being
discovered.
13.7.2 Marine Fauna
Bioactive compounds from marine fauna have been used as antimicrobials from
olden times. Therapeutically important compounds are isolated mainly from invertebrates such as sponges, cnidarians, annelids, arthopods, molluscs, etc. Major
classes of marine animal derived compounds are steroids, terpenoids, isoprenoids,
nonisoprenoids, quinones, brominated compounds, nitrogen heterocyclics, nitrogen
sulfur heterocyclics, etc. They are used as natural molecules or as synthetically
modified compounds. These compounds are used against various pathogenic microorganisms including bacteria, virus, fungi, protozoan, helminthic parasites, etc.
(Bhakuni and Rawat 2006).
Sponges are very simple, cellular grade (no organized tissues) multicellular
organisms found in aquatic habitats. They are the richest source of bioactive compounds in the marine environment. These compounds are generally the secondary
metabolites originated from sponges and their symbionts by the action of functional
enzyme clusters (Laport et al. 2009; Sagar et al. 2010). Sponges alone produce more
13 Novel Sources of Antimicrobials