138 Marine Macro- and Microalgae: An Overview
Rhodophyta (19 species/13 families) algae (Wright and König 1996; Topcu et al. 2003; MendiolaMartínez et al. 2005; Lakshimi et al. 2006; Orhan et al. 2006; Süzgeç-Selçuk et al. 2010; VonthronSénécheau et al. 2011). Algae with IC 50 for antiplasmodial activity, under 25 μg/mL are summarized in
Table 4.
The data reported for the screening of antiplasmodial activity of marine algae, were obtained towards
P. falciparum erythrocytic stages using [3H]-hypoxanthine incorporation assay. Only Lakshimi et al.
2006 have tested chlorophyta algae species against P. berghei without antiplasmodial results.
As for the L. donovani and T. brucei rhodesiense, the methanolic extracts of the Rhodophyta Dasya
pedicellata and the Chlorophyta Codium bursa were the most potent against P. falciparum evidencing
IC 50 ’s of 0.38 μg/mL and 1.38 μg/mL, respectively (Süzgeç-Selçuk et al. 2010). The ethyl acetate extracts
of the rhodophytes Mastocarpus stellatus, Chondrus crispus, Grateloupia turuturu, Gracilaria gracilis,
Gelidium latifolium, Dilsea carnosa, Halurus flosculosus and Ochrophytas Sargassum muticum, Dictyota
dichotoma, Himanthalia elongata, and the methanolic extract of the Chlorophyta Caulerpa racemosa,
revealed inhibitory activities between 2.8 and 4.6 μg/mL (Süzgeç-Selçuk et al. 2010; Vonthron-Sénécheau
et al. 2011).
Concerning the works involving isolated compounds, once more the sesquiterpenes ((8R)-8bromo-10-epi-beta-snyderol) and aromatic compounds (p-hydroxybenzaldehyde and p-methoxy-benzyl)
isolated from Laurencia sp. show antimalarial activity (Wright et al. 1996; Topcu et al. 2003). Chen et al.
(2009) indicates that fucoidan, a sulfated polysaccharide, isolated from the Korean brown algae Undaria
pinnatifida inhibits the invasion of Plasmodium falciparum merozoites into erythrocytes in vitro and in in
vivo Plasmodium berghei-infected mice, and had no toxic effect on RAW 264.7 cells.
Orhan et al. (2006) had evaluated the ability of five ethanolic extracts of turkish seaweeds to inhibit
the recombinant key enzyme (FabI) of the fatty acid biosynthesis of P. falciparum in vitro. Despite its
moderate antiplasmodial activity, the green algae C. glomerata (IC 50 = 33.7 μg/mL) and U. lactuca
(IC 50 = 48.8 μg/mL) efficiently inhibited the FabI enzyme with IC 50 values of 1.0 and 4.0 μg/mL,
respectively, suggesting that this species might represent alternative sources in the search of new
antiprotozoal agents.
Concerning the extraction procedures for antiplasmodial screenings of marine algae, only ethyl
acetate, ethanol, and methanol extracts were surveyed. In agreement with previously described for
antileishmanial and antitrypanossomal activities, ethanolic extracts were less active or even inactive
against P. falciparum parasites (Vonthron-Sénécheau et al. 2011).
The search for bioactive compounds originating from the sea is recent. However, based on the
enormous amount of data collected so far, it is possible to note that marine algal extracts are promising
sources of novel antiparasitic chemotherapeutic compounds and that further research is needed to identify
them.
Concluding remarks
Marine algae are novel and important sources of bioactive compounds, which can be used as pharmaceutical
agents in the near future. Often, however, the structure of natural bioactive compounds is complex, which
hinders their identification, isolation, and synthesis, as well as a better understanding of the molecular
mechanisms involved. Moreover, insufficient yields can also become a limitation. Nonetheless, the wide
spectrum of bioactivities found in marine algae underlines the important potential application of algal
compounds in the pharmaceutical industry, which can complement and inspire the synthesis of novel
synthetic drugs that can improve the quality of life for all humankind.
Acknowledgements
This work was supported by Portuguese FCT – Fundação para a Ciência e a Tecnologia through the
PTDC/MAR/103957/2008 and CCMAR/Multi/04326/2013 projects. CVD and CBS were supported by
FCT doctoral grants (SFRH/BD/81425/2011 and SFRH/BD/78062/2011, respectively) and LC by the
FCT Investigator Programme (IF/00049/2012).
Rhodophyta (19 species/13 families) algae (Wright and König 1996; Topcu et al. 2003; MendiolaMartínez et al. 2005; Lakshimi et al. 2006; Orhan et al. 2006; Süzgeç-Selçuk et al. 2010; VonthronSénécheau et al. 2011). Algae with IC 50 for antiplasmodial activity, under 25 μg/mL are summarized in
Table 4.
The data reported for the screening of antiplasmodial activity of marine algae, were obtained towards
P. falciparum erythrocytic stages using [3H]-hypoxanthine incorporation assay. Only Lakshimi et al.
2006 have tested chlorophyta algae species against P. berghei without antiplasmodial results.
As for the L. donovani and T. brucei rhodesiense, the methanolic extracts of the Rhodophyta Dasya
pedicellata and the Chlorophyta Codium bursa were the most potent against P. falciparum evidencing
IC 50 ’s of 0.38 μg/mL and 1.38 μg/mL, respectively (Süzgeç-Selçuk et al. 2010). The ethyl acetate extracts
of the rhodophytes Mastocarpus stellatus, Chondrus crispus, Grateloupia turuturu, Gracilaria gracilis,
Gelidium latifolium, Dilsea carnosa, Halurus flosculosus and Ochrophytas Sargassum muticum, Dictyota
dichotoma, Himanthalia elongata, and the methanolic extract of the Chlorophyta Caulerpa racemosa,
revealed inhibitory activities between 2.8 and 4.6 μg/mL (Süzgeç-Selçuk et al. 2010; Vonthron-Sénécheau
et al. 2011).
Concerning the works involving isolated compounds, once more the sesquiterpenes ((8R)-8bromo-10-epi-beta-snyderol) and aromatic compounds (p-hydroxybenzaldehyde and p-methoxy-benzyl)
isolated from Laurencia sp. show antimalarial activity (Wright et al. 1996; Topcu et al. 2003). Chen et al.
(2009) indicates that fucoidan, a sulfated polysaccharide, isolated from the Korean brown algae Undaria
pinnatifida inhibits the invasion of Plasmodium falciparum merozoites into erythrocytes in vitro and in in
vivo Plasmodium berghei-infected mice, and had no toxic effect on RAW 264.7 cells.
Orhan et al. (2006) had evaluated the ability of five ethanolic extracts of turkish seaweeds to inhibit
the recombinant key enzyme (FabI) of the fatty acid biosynthesis of P. falciparum in vitro. Despite its
moderate antiplasmodial activity, the green algae C. glomerata (IC 50 = 33.7 μg/mL) and U. lactuca
(IC 50 = 48.8 μg/mL) efficiently inhibited the FabI enzyme with IC 50 values of 1.0 and 4.0 μg/mL,
respectively, suggesting that this species might represent alternative sources in the search of new
antiprotozoal agents.
Concerning the extraction procedures for antiplasmodial screenings of marine algae, only ethyl
acetate, ethanol, and methanol extracts were surveyed. In agreement with previously described for
antileishmanial and antitrypanossomal activities, ethanolic extracts were less active or even inactive
against P. falciparum parasites (Vonthron-Sénécheau et al. 2011).
The search for bioactive compounds originating from the sea is recent. However, based on the
enormous amount of data collected so far, it is possible to note that marine algal extracts are promising
sources of novel antiparasitic chemotherapeutic compounds and that further research is needed to identify
them.
Concluding remarks
Marine algae are novel and important sources of bioactive compounds, which can be used as pharmaceutical
agents in the near future. Often, however, the structure of natural bioactive compounds is complex, which
hinders their identification, isolation, and synthesis, as well as a better understanding of the molecular
mechanisms involved. Moreover, insufficient yields can also become a limitation. Nonetheless, the wide
spectrum of bioactivities found in marine algae underlines the important potential application of algal
compounds in the pharmaceutical industry, which can complement and inspire the synthesis of novel
synthetic drugs that can improve the quality of life for all humankind.
Acknowledgements
This work was supported by Portuguese FCT – Fundação para a Ciência e a Tecnologia through the
PTDC/MAR/103957/2008 and CCMAR/Multi/04326/2013 projects. CVD and CBS were supported by
FCT doctoral grants (SFRH/BD/81425/2011 and SFRH/BD/78062/2011, respectively) and LC by the
FCT Investigator Programme (IF/00049/2012).