Holothuroidea
Secondary metabolites from holothurians are characterized by the presence of
triterpenoidal saponins (holothurins) and can be considered characteristic of the
class. Their toxicity (acting as membranotropic towards cell membranes) can be
associated with a defensive response of the organism and is the cause of their
biological activity (Maier 2008). They have also been used as chemotaxonomic
markers since some holothurins are specific for different taxa (see Maier and
Murray 2006; Antonov et al. 2008).
Two species of holothurians from the Patagonian coast of Argentina have been
studied: Hemioedema spectabilis (collected at SJOG) and Psolus patagonicus
(collected off Bahía Ensenada; 54°50
0 S, 68°29
0 W). Patagonicoside A, the major
component of the ethanolic extract of P. patagonicus was isolated and its structure
was determined by Murray et al. (2001) (Fig. 11.5d). Patagonicoside A has
revealed a broad spectrum of biological activities: the glycoside and its semisynthetic desulfated analogue were tested for their antifungal activity against the
phytopathogenic fungi Cladosporium cucumerinum (Murray et al. 2001), C. fulvum, Fusarium oxysporum and Monilia sp. (Muniain et al. 2008). The intact
compound is more effective than the desulfated analogue. It showed an antifungal
activity comparable with a commercial fungicide towards Monilia sp. Bioactivity
assays showed that the presence of the sulphate groups in the oligosaccharide
chain plays an important role in the antifungal activity. Patagonicoside A and the
desulfated derivative were also tested for antiproliferative, cytotoxic and haemolytic activities and their effect on NF-jB activation (Careaga et al. 2009). Both
glycosides showed low cytotoxic activity in A549 tumour cells, which the authors
attribute to the uncommon presence of 12a,17a-hydroxyl groups in the aglycone
moiety. Both compounds exert an antiproliferative effect although their mechanisms of action do not involve inhibition of NF-jB.
Chludil et al. (2002b) isolated and described two new sulfated triterpene glycosides, Hemoiedemosides A and B from the Patagonian holothurian H. spectabilis (Fig. 11.6a). Hemoiedemoside B is a new example of a small number of
trisulfated triterpene glycosides from holothurians belonging to the family Cucumariidae. Both glycosides exhibit considerable antifungal activity against the
phytopathogenic fungus C. cucumerinum, while the semisynthetic desulfated
derivative of Hemoiedemoside A is less active.
11.4 Aquaculture and Fisheries
Although fisheries of the sea urchin Loxechinus albus has been extensive in Chile,
in Argentina it has been captured only sporadically by artisanal fisheries in the
Beagle Channel near Ushuaia Bay, especially for the local market, to serve tourists
from the Orient, and occasionally exported to Chile.
386
M. I. Brogger et al.
Secondary metabolites from holothurians are characterized by the presence of
triterpenoidal saponins (holothurins) and can be considered characteristic of the
class. Their toxicity (acting as membranotropic towards cell membranes) can be
associated with a defensive response of the organism and is the cause of their
biological activity (Maier 2008). They have also been used as chemotaxonomic
markers since some holothurins are specific for different taxa (see Maier and
Murray 2006; Antonov et al. 2008).
Two species of holothurians from the Patagonian coast of Argentina have been
studied: Hemioedema spectabilis (collected at SJOG) and Psolus patagonicus
(collected off Bahía Ensenada; 54°50
0 S, 68°29
0 W). Patagonicoside A, the major
component of the ethanolic extract of P. patagonicus was isolated and its structure
was determined by Murray et al. (2001) (Fig. 11.5d). Patagonicoside A has
revealed a broad spectrum of biological activities: the glycoside and its semisynthetic desulfated analogue were tested for their antifungal activity against the
phytopathogenic fungi Cladosporium cucumerinum (Murray et al. 2001), C. fulvum, Fusarium oxysporum and Monilia sp. (Muniain et al. 2008). The intact
compound is more effective than the desulfated analogue. It showed an antifungal
activity comparable with a commercial fungicide towards Monilia sp. Bioactivity
assays showed that the presence of the sulphate groups in the oligosaccharide
chain plays an important role in the antifungal activity. Patagonicoside A and the
desulfated derivative were also tested for antiproliferative, cytotoxic and haemolytic activities and their effect on NF-jB activation (Careaga et al. 2009). Both
glycosides showed low cytotoxic activity in A549 tumour cells, which the authors
attribute to the uncommon presence of 12a,17a-hydroxyl groups in the aglycone
moiety. Both compounds exert an antiproliferative effect although their mechanisms of action do not involve inhibition of NF-jB.
Chludil et al. (2002b) isolated and described two new sulfated triterpene glycosides, Hemoiedemosides A and B from the Patagonian holothurian H. spectabilis (Fig. 11.6a). Hemoiedemoside B is a new example of a small number of
trisulfated triterpene glycosides from holothurians belonging to the family Cucumariidae. Both glycosides exhibit considerable antifungal activity against the
phytopathogenic fungus C. cucumerinum, while the semisynthetic desulfated
derivative of Hemoiedemoside A is less active.
11.4 Aquaculture and Fisheries
Although fisheries of the sea urchin Loxechinus albus has been extensive in Chile,
in Argentina it has been captured only sporadically by artisanal fisheries in the
Beagle Channel near Ushuaia Bay, especially for the local market, to serve tourists
from the Orient, and occasionally exported to Chile.
386
M. I. Brogger et al.