C. Naphthalene Derivatives
93
surprisingly then, for a long time quinone pigment research dealt exclusively
with members of this one class. It was therefore tacitly assumed that occurrence of naphthoquinone pigments was confined to the echinoids. The first
documented isolation and identification of a naphthoquinone pigment from
an echinoderm that was not a sea urchin was reported from a group at
Kyushu University in Japan (Mukai, 1958, 1960; Yamaguchi et al, 1961).
Mukai and co-workers isolated from a sea cucumber, Polycheira rufescens, a
polyhydroxynaphthoquinone which they subsequently identified as the monomethyl ether of a known sea urchin pigment (see Section C,l,f). At about the
same time Sutherland and his group in Australia (Sutherland and Wells,
1959) reported the isolation of an anthraquinone pigment from a crinoid (see
Section D). This discovery pointed to confirmation of the generally held
assumption that naphthoquinone pigments are essentially an exclusive
property of sea urchins. Mukai's isolation from an holothurian was considered exceptional. The known distribution of naphthoquinone pigments in
echinoids has been carefully documented by Anderson et al (1969).
However, Scheuer and his group (Singh et al, 1967) examined the pigments
of the two classes of echinoderms that had not previously been studied. They
were able to show that naphthoquinone pigments do occur in the asteroids
and in the ophiuroids. Interestingly, Singh et al (1967) found that the pigments of the sea star Acanthaster planci are methyl ethers of known sea urchin
pigments, whereas the range of pigments in the two species of brittlestars,
Ophiocoma erinaceus and O. insularia, closely parallels that found in the sea
urchins. Singh et al (1967) concluded from their findings that quinone
pigment distribution—polyhydroxynaphthoquinones from sea urchins and
brittlestars, partial methyl ethers from sea stars and sea cucumbers—was in
line with other chemical parameters, triterpenoids and sterols, that linked the
two respective pairs of echinoderms. This early conclusion has since been
weakened by Mathieson and Thomson's (1971) discovery of methylated
pigments in sea urchins. Further work is necessary on more than a few isolated
species in order to clarify these relationships.
Singh et al (1967) also examined one species of crinoid in an attempt to
check whether this class of animals elaborates anthraquinones exclusively.
These workers isolated from Antedon sp. small quantities of two known sea
urchin pigments in addition to large amounts of nonnaphthoquinone pigments,
which they did not study. Since then Sutherland's group (Kent et al, 1970;
Smith and Sutherland, 1971) has discovered naphthopyrone pigments in
crinoids, thus making the crinoids the most versatile of the echinoderms in
pigment elaboration. Interestingly, crinoids are the earliest echinoderms to
appear in the fossil record and may well be the ancestors of all echinoderms.
Further work on crinoid pigments should be rewarding, but is hampered by
the geographically restricted availability of this class of echinoderms.
93
surprisingly then, for a long time quinone pigment research dealt exclusively
with members of this one class. It was therefore tacitly assumed that occurrence of naphthoquinone pigments was confined to the echinoids. The first
documented isolation and identification of a naphthoquinone pigment from
an echinoderm that was not a sea urchin was reported from a group at
Kyushu University in Japan (Mukai, 1958, 1960; Yamaguchi et al, 1961).
Mukai and co-workers isolated from a sea cucumber, Polycheira rufescens, a
polyhydroxynaphthoquinone which they subsequently identified as the monomethyl ether of a known sea urchin pigment (see Section C,l,f). At about the
same time Sutherland and his group in Australia (Sutherland and Wells,
1959) reported the isolation of an anthraquinone pigment from a crinoid (see
Section D). This discovery pointed to confirmation of the generally held
assumption that naphthoquinone pigments are essentially an exclusive
property of sea urchins. Mukai's isolation from an holothurian was considered exceptional. The known distribution of naphthoquinone pigments in
echinoids has been carefully documented by Anderson et al (1969).
However, Scheuer and his group (Singh et al, 1967) examined the pigments
of the two classes of echinoderms that had not previously been studied. They
were able to show that naphthoquinone pigments do occur in the asteroids
and in the ophiuroids. Interestingly, Singh et al (1967) found that the pigments of the sea star Acanthaster planci are methyl ethers of known sea urchin
pigments, whereas the range of pigments in the two species of brittlestars,
Ophiocoma erinaceus and O. insularia, closely parallels that found in the sea
urchins. Singh et al (1967) concluded from their findings that quinone
pigment distribution—polyhydroxynaphthoquinones from sea urchins and
brittlestars, partial methyl ethers from sea stars and sea cucumbers—was in
line with other chemical parameters, triterpenoids and sterols, that linked the
two respective pairs of echinoderms. This early conclusion has since been
weakened by Mathieson and Thomson's (1971) discovery of methylated
pigments in sea urchins. Further work is necessary on more than a few isolated
species in order to clarify these relationships.
Singh et al (1967) also examined one species of crinoid in an attempt to
check whether this class of animals elaborates anthraquinones exclusively.
These workers isolated from Antedon sp. small quantities of two known sea
urchin pigments in addition to large amounts of nonnaphthoquinone pigments,
which they did not study. Since then Sutherland's group (Kent et al, 1970;
Smith and Sutherland, 1971) has discovered naphthopyrone pigments in
crinoids, thus making the crinoids the most versatile of the echinoderms in
pigment elaboration. Interestingly, crinoids are the earliest echinoderms to
appear in the fossil record and may well be the ancestors of all echinoderms.
Further work on crinoid pigments should be rewarding, but is hampered by
the geographically restricted availability of this class of echinoderms.