Marine Algal Bioactivities 131
The species D. humifusa and U. fasciata had the highest capacity to inhibit the activity of AChE, with
IC 50 values of 4.8 mg/mL. The species Hypnea valentiae (IC 50 = 2.6 mg/mL), and Gracilaria edulis
(IC 50 = 3 mg/mL) collected from Hare Island, Gulf of Mannar (India) also exhibited promising AChE
inhibitory potential. Strong AChE inhibitory activity was detected on methanol extracts of the species
Gracilaria gracilis, Sargassum, and Cladophora fasicularis at the concentrations of 1.5, 1, and 2 mg/mL
respectively (Suganthy et al. 2010). In addition, Hypnea valentiae and Ulva reticulate exhibited dual anticholinesterase activity, that is, they are active against both AChE and BChE, with IC 50 values on BChE of
3.9 mg/mL and 10 mg/mL, respectively (Suganthy et al. 2010). Compounds with dual anti-ChE activity
may be appropriate to patients at a moderate stage of AD if ACh levels have not yet significantly declined
and BChE could hydrolyse ACh (Mesulam et al. 2002). Indeed, tacrine and physostigmine, which are
drugs used in the clinical treatment of AD, exhibit mixed AChE-BChE inhibition.
Myung et al. (2005) reported that dieckol and phlorofucofluoroeckol, two phlorotannins found in
the brown algae Ecklonia cava have memory enhancing and AChE inhibitory activities. Working with
ethanolic extracts of 27 Korean marine algae, Yoon et al. (2008) found that Ecklonia stolonifera has
significant inhibitory activity against AChE. The bioassay-guided fractionation of the active hexane and
ethyl acetate fractions, obtained from the ethanolic extract of E. stolonifera allowed the isolation of
eight phlorotannins (phloroglucinol, eckstolonol, eckol, phlorofucofuroeckol-A, dieckol, triphlorethol-A,
2-phloroeckol, and 7-phloroeckol), and two sterols (fucosterol and 24-hydroperoxy 24-vinylcholesterol).
Eckol, dieckol, 2-phloroeckol, and 7-phloroeckol exhibited selective dose dependent inhibitory activities
toward AChE; while eckstolonol and phlorofucofuroeckol-A had inhibitory activities against both AChE
and BChE. Plastoquinones isolated from Sargassum sagamianum have also been found to be potent ChEi
(Choi et al. 2007).
Microalgae have a distinct biochemistry and are considered as one of the most promising sources
of functional molecules (Pulz and Gross 2004; Chacón-Lee and González-Maríño 2010). In spite of
this, little is known of its neuroprotective potential. Working with methanol and hexane extracts of
different microalgae species, Custódio et al. (2012) found a significant AChE inhibitory activity in the
hexane extracts of Mychonastes homosphaera (formerly known as Chlorella minutissima), Tetraselmis
chuii, and Rhodomonas salina, which resulted in an AChE inhibition ranging between 79 and 86% at a
concentration of 10 mg/mL. A high AChE inhibitory capacity was also detected by the same authors in
water and diethyl ether extracts of Scenedesmus sp. (Custódio et al. 2013). Taken together, these results
point to a possible therapeutic value of bioactive molecules present in macro- and microalgae as ChEi,
with application in the management of AD and other neurological disorders. Moreover, some compounds
isolated from macroalgae exhibit dual anti-ChE activity, which is considered to be more effective in the
treatment of AD.
Anti-protozoal activities
Vector-borne parasitic diseases—for example, malaria, Chagas disease, African trypanosomiasis,
and leishmaniasis—caused by unicellular flagellates such as Plasmodium sp., Trypanosoma sp., and
Leishmania sp. constitute one of the major challenges for global health. The human importance of these
infectious diseases is annually confirmed by WHO reports and initiatives (WHO 2010a,b, 2011, 2012a,b).
Besides being a major cause of mortality in various tropical and subtropical regions (WHO 2008), these
diseases generate an enormous impact in terms of disease burden, quality of life, loss of productivity,
and the aggravation of poverty as well as the high cost of long-term care, being a serious obstacle to the
socio-economic development, especially in developing countries (WHO 2010b).
Terrestrial plants have been used commonly as natural sources of antiprotozoal compounds (Wright
and Phillipson 1990). Although to a less extent, marine algae have also been used by coastal Asia and
Caribbean people in traditional medicine (Moo-Puc et al. 2008), and there are ancient Chinese records of
its use upon boiling in antiparasitic treatments (Tseng and Chang 1984).
As in land plants, the interest in the chemical wealth of marine organisms as a potential source of
antiprotozoal pharmacological agents has increased over the last few years (Fattorusso and TaglialatelaScafati 2009; Mayer et al. 2011; Tempone et al. 2011). Since the early 2000s there has been a focus on
The species D. humifusa and U. fasciata had the highest capacity to inhibit the activity of AChE, with
IC 50 values of 4.8 mg/mL. The species Hypnea valentiae (IC 50 = 2.6 mg/mL), and Gracilaria edulis
(IC 50 = 3 mg/mL) collected from Hare Island, Gulf of Mannar (India) also exhibited promising AChE
inhibitory potential. Strong AChE inhibitory activity was detected on methanol extracts of the species
Gracilaria gracilis, Sargassum, and Cladophora fasicularis at the concentrations of 1.5, 1, and 2 mg/mL
respectively (Suganthy et al. 2010). In addition, Hypnea valentiae and Ulva reticulate exhibited dual anticholinesterase activity, that is, they are active against both AChE and BChE, with IC 50 values on BChE of
3.9 mg/mL and 10 mg/mL, respectively (Suganthy et al. 2010). Compounds with dual anti-ChE activity
may be appropriate to patients at a moderate stage of AD if ACh levels have not yet significantly declined
and BChE could hydrolyse ACh (Mesulam et al. 2002). Indeed, tacrine and physostigmine, which are
drugs used in the clinical treatment of AD, exhibit mixed AChE-BChE inhibition.
Myung et al. (2005) reported that dieckol and phlorofucofluoroeckol, two phlorotannins found in
the brown algae Ecklonia cava have memory enhancing and AChE inhibitory activities. Working with
ethanolic extracts of 27 Korean marine algae, Yoon et al. (2008) found that Ecklonia stolonifera has
significant inhibitory activity against AChE. The bioassay-guided fractionation of the active hexane and
ethyl acetate fractions, obtained from the ethanolic extract of E. stolonifera allowed the isolation of
eight phlorotannins (phloroglucinol, eckstolonol, eckol, phlorofucofuroeckol-A, dieckol, triphlorethol-A,
2-phloroeckol, and 7-phloroeckol), and two sterols (fucosterol and 24-hydroperoxy 24-vinylcholesterol).
Eckol, dieckol, 2-phloroeckol, and 7-phloroeckol exhibited selective dose dependent inhibitory activities
toward AChE; while eckstolonol and phlorofucofuroeckol-A had inhibitory activities against both AChE
and BChE. Plastoquinones isolated from Sargassum sagamianum have also been found to be potent ChEi
(Choi et al. 2007).
Microalgae have a distinct biochemistry and are considered as one of the most promising sources
of functional molecules (Pulz and Gross 2004; Chacón-Lee and González-Maríño 2010). In spite of
this, little is known of its neuroprotective potential. Working with methanol and hexane extracts of
different microalgae species, Custódio et al. (2012) found a significant AChE inhibitory activity in the
hexane extracts of Mychonastes homosphaera (formerly known as Chlorella minutissima), Tetraselmis
chuii, and Rhodomonas salina, which resulted in an AChE inhibition ranging between 79 and 86% at a
concentration of 10 mg/mL. A high AChE inhibitory capacity was also detected by the same authors in
water and diethyl ether extracts of Scenedesmus sp. (Custódio et al. 2013). Taken together, these results
point to a possible therapeutic value of bioactive molecules present in macro- and microalgae as ChEi,
with application in the management of AD and other neurological disorders. Moreover, some compounds
isolated from macroalgae exhibit dual anti-ChE activity, which is considered to be more effective in the
treatment of AD.
Anti-protozoal activities
Vector-borne parasitic diseases—for example, malaria, Chagas disease, African trypanosomiasis,
and leishmaniasis—caused by unicellular flagellates such as Plasmodium sp., Trypanosoma sp., and
Leishmania sp. constitute one of the major challenges for global health. The human importance of these
infectious diseases is annually confirmed by WHO reports and initiatives (WHO 2010a,b, 2011, 2012a,b).
Besides being a major cause of mortality in various tropical and subtropical regions (WHO 2008), these
diseases generate an enormous impact in terms of disease burden, quality of life, loss of productivity,
and the aggravation of poverty as well as the high cost of long-term care, being a serious obstacle to the
socio-economic development, especially in developing countries (WHO 2010b).
Terrestrial plants have been used commonly as natural sources of antiprotozoal compounds (Wright
and Phillipson 1990). Although to a less extent, marine algae have also been used by coastal Asia and
Caribbean people in traditional medicine (Moo-Puc et al. 2008), and there are ancient Chinese records of
its use upon boiling in antiparasitic treatments (Tseng and Chang 1984).
As in land plants, the interest in the chemical wealth of marine organisms as a potential source of
antiprotozoal pharmacological agents has increased over the last few years (Fattorusso and TaglialatelaScafati 2009; Mayer et al. 2011; Tempone et al. 2011). Since the early 2000s there has been a focus on