36
/. Isoprenoids
a calcareous shell or test, are very beautiful in shape and color. Commonly
they have five arms, although the most notorious species of recent years,
Acanthaster planci, the coral-eating one, does not. Few if any casual observers
would suspect that asteroids and holothurians have many common characteristics.
Hashimoto and Yasumoto (1960) first recognized the occurrence of a
"saponin" in the asteroids. Several years later Hashimoto and his group
(Yasumoto et al., 1966) surveyed all five classes of echinoderms and found
that only the holothurians and the asteroids contain these compounds,
while the echinoids, ophiuroids, and crinoids do not. This finding reinforces
the suspected close relationship of sea cucumbers and sea stars, which has
also been suggested on the basis of two chemical parameters: A
7 -sterols by
Gupta and Scheuer (1968) and naphthoquinone pigments by Singh et al.
(1967).
Following their recognition of sea star (astero) saponins Hashimoto
and his group studied a number of them. From Asterias amurensis Yasumoto
and Hashimoto (1965) isolated a mixture of six triterpenoid glycosides and
designated the major component asterosaponin A. On acid hydrolysis
the glycoside yielded 2 moles of D-quinovose (62) and 2 moles of D-fucose
(87) in addition to sulfuric acid. The aglycone presented spectral evidence for
a heteroannular diene, a characteristic structural feature of the holothurinogenins, but lacked spectral evidence for a lactone. A second glycoside, asterosaponin B, was isolated by Yasumoto and Hashimoto (1967) from the same
asteroid. Acid hydrolysis furnished 2 moles of D-quinovose (62), 1 mole each
of D-fucose (87), D-xylose (60), and D-galactose (88), and sulfuric acid.
Prior to hydrolysis asterosaponin Β exhibits an ultraviolet band at 248 nm
and infrared bands at 1700 and 1640 cm
- 1 . These data indicate that asterosaponin Β differs distinctly from the known holothurins and from asterosaponin A. Two aglycones have been partially characterized; one contains a
conjugated, the other an isolated carbonyl group.
CH 3
CH a OH
HO^|^
Q ^°
H
^^^^
OH
OH
87
88
Friess and co-workers (1968) have recently made physiological comparisons
of the characterized holothurins A and Β and the asterosaponins A and B.
Their experiments led them to conclude that the key to differential physiological activity lies in the nature of the sugars, their sequences, and the
/. Isoprenoids
a calcareous shell or test, are very beautiful in shape and color. Commonly
they have five arms, although the most notorious species of recent years,
Acanthaster planci, the coral-eating one, does not. Few if any casual observers
would suspect that asteroids and holothurians have many common characteristics.
Hashimoto and Yasumoto (1960) first recognized the occurrence of a
"saponin" in the asteroids. Several years later Hashimoto and his group
(Yasumoto et al., 1966) surveyed all five classes of echinoderms and found
that only the holothurians and the asteroids contain these compounds,
while the echinoids, ophiuroids, and crinoids do not. This finding reinforces
the suspected close relationship of sea cucumbers and sea stars, which has
also been suggested on the basis of two chemical parameters: A
7 -sterols by
Gupta and Scheuer (1968) and naphthoquinone pigments by Singh et al.
(1967).
Following their recognition of sea star (astero) saponins Hashimoto
and his group studied a number of them. From Asterias amurensis Yasumoto
and Hashimoto (1965) isolated a mixture of six triterpenoid glycosides and
designated the major component asterosaponin A. On acid hydrolysis
the glycoside yielded 2 moles of D-quinovose (62) and 2 moles of D-fucose
(87) in addition to sulfuric acid. The aglycone presented spectral evidence for
a heteroannular diene, a characteristic structural feature of the holothurinogenins, but lacked spectral evidence for a lactone. A second glycoside, asterosaponin B, was isolated by Yasumoto and Hashimoto (1967) from the same
asteroid. Acid hydrolysis furnished 2 moles of D-quinovose (62), 1 mole each
of D-fucose (87), D-xylose (60), and D-galactose (88), and sulfuric acid.
Prior to hydrolysis asterosaponin Β exhibits an ultraviolet band at 248 nm
and infrared bands at 1700 and 1640 cm
- 1 . These data indicate that asterosaponin Β differs distinctly from the known holothurins and from asterosaponin A. Two aglycones have been partially characterized; one contains a
conjugated, the other an isolated carbonyl group.
CH 3
CH a OH
HO^|^
Q ^°
H
^^^^
OH
OH
87
88
Friess and co-workers (1968) have recently made physiological comparisons
of the characterized holothurins A and Β and the asterosaponins A and B.
Their experiments led them to conclude that the key to differential physiological activity lies in the nature of the sugars, their sequences, and the