7
Marine Algal Bioactivities
Catarina Vizetto-Duarte, Carolina Bruno de Sousa, Maria Rodrigues,
Luísa Custódio, Luísa Barreira and João Varela*
Introduction
Biological activity can be defined as the specific effect of, or a reaction to, exposure of a living organism/
tissue/cell to a given compound or mix of compounds (e.g., extracts). Humans have explored different
terrestrial plants as sources of bio-compounds for centuries. However, historically, marine organisms
have had a limited number of reported applications in traditional medicine as compared to their terrestrial
counterparts. Even so, the exploration of the marine environment has resulted in the isolation of thousands
of structurally distinctive bioactive natural products (Haefner 2003).
Algae are promising sources of novel natural compounds with biological activities. Because of their
exclusive features during evolution, algae spread to every known habitat including aquatic, terrestrial,
and sub-aerial environments (Metting 1996). Since biodiversity is vital in the prospection for new
chemical entities in drug discovery research, algae can be seen as a crucial field for the exploration of
new biologically active compounds. Apart from being potential sources of natural products, algae present
unique features such as easy cultivation and rapid growth for many species with commercial value, as
well as the possibility of controlling the production of some bioactive compounds by manipulating the
cultivation conditions (Kim et al. 2007; Sánchez et al. 2008). In this way, macro- and microalgae can
be considered as genuine natural reactors being, in some cases, a good alternative to chemical synthesis
for certain compounds. Several species live in complex habitats submitted to extreme abiotic conditions
(e.g., salinity, temperature, nutrients, UV-Vis irradiation, and pressure) and their adaptation to these
extreme environmental conditions includes the production of a great variety of secondary metabolites,
which cannot be found in other organisms (Carlucci et al. 1999).
Formerly called blue-green algae, cyanobacteria are a diverse group of Gram-negative
photosynthetic bacteria that produce an array of secondary metabolites with relevant bioactivities such as
antifungal, antiviral, antibiotic, and cytotoxic, which make them also interesting candidates of potential
pharmaceutical importance (Dittmann et al. 2001). However, this chapter will not focus on bioactivities
displayed by compounds from cyanobacteria since nowadays most authors do not consider them as algae.
Secondary metabolites are generally produced either as a result of the acclimation and/or adaptation
of an organism to its surrounding environment, or as a defence mechanism against predators (Dewick
2002). The processes by which an organism produces these compounds are found in specific groups of
Centre of Marine Sciences, Universidade do Algarve, Ed. 7, Campus de Gambelas, 8005-139 Faro, Portugal.
* Corresponding author: jvarela@ualg.pt
Marine Algal Bioactivities
Catarina Vizetto-Duarte, Carolina Bruno de Sousa, Maria Rodrigues,
Luísa Custódio, Luísa Barreira and João Varela*
Introduction
Biological activity can be defined as the specific effect of, or a reaction to, exposure of a living organism/
tissue/cell to a given compound or mix of compounds (e.g., extracts). Humans have explored different
terrestrial plants as sources of bio-compounds for centuries. However, historically, marine organisms
have had a limited number of reported applications in traditional medicine as compared to their terrestrial
counterparts. Even so, the exploration of the marine environment has resulted in the isolation of thousands
of structurally distinctive bioactive natural products (Haefner 2003).
Algae are promising sources of novel natural compounds with biological activities. Because of their
exclusive features during evolution, algae spread to every known habitat including aquatic, terrestrial,
and sub-aerial environments (Metting 1996). Since biodiversity is vital in the prospection for new
chemical entities in drug discovery research, algae can be seen as a crucial field for the exploration of
new biologically active compounds. Apart from being potential sources of natural products, algae present
unique features such as easy cultivation and rapid growth for many species with commercial value, as
well as the possibility of controlling the production of some bioactive compounds by manipulating the
cultivation conditions (Kim et al. 2007; Sánchez et al. 2008). In this way, macro- and microalgae can
be considered as genuine natural reactors being, in some cases, a good alternative to chemical synthesis
for certain compounds. Several species live in complex habitats submitted to extreme abiotic conditions
(e.g., salinity, temperature, nutrients, UV-Vis irradiation, and pressure) and their adaptation to these
extreme environmental conditions includes the production of a great variety of secondary metabolites,
which cannot be found in other organisms (Carlucci et al. 1999).
Formerly called blue-green algae, cyanobacteria are a diverse group of Gram-negative
photosynthetic bacteria that produce an array of secondary metabolites with relevant bioactivities such as
antifungal, antiviral, antibiotic, and cytotoxic, which make them also interesting candidates of potential
pharmaceutical importance (Dittmann et al. 2001). However, this chapter will not focus on bioactivities
displayed by compounds from cyanobacteria since nowadays most authors do not consider them as algae.
Secondary metabolites are generally produced either as a result of the acclimation and/or adaptation
of an organism to its surrounding environment, or as a defence mechanism against predators (Dewick
2002). The processes by which an organism produces these compounds are found in specific groups of
Centre of Marine Sciences, Universidade do Algarve, Ed. 7, Campus de Gambelas, 8005-139 Faro, Portugal.
* Corresponding author: jvarela@ualg.pt