which were collected in the Bay of Naples, Italy (Fig. 32). In addition, 46 has been
reported from a sponge Spongia sp. collected in Western Australia [37], and
tetradehydrofurospongin-1 (47) has been found in both the Leiosella sp. and Spongia
sp. sponges (Fig. 32) [37, 38].
On the other hand, furospongolide (48), from the sponge Dysidea herbacea
(Fig. 33) [39], possesses one furan ring moiety and one 2-furanone moiety at the
ends of the molecule.
3.4.2 “C 24 ” Linear Sesterterpenoids
The C 24 linear sesterterpenoids are also considered to be formed from the linear
sesterterpenoids with a tetronic acid moiety. In the case of the C 24 linear
O
OH
OH
OH
42
43
44
45
46
47
furan ring moieties at both ends of molecule
O
O
O
O
O
O
O
O
O
O
O
O
O
O
Fig. 32 Structures of 42–
47. These are C 21 linear
sesterterpenoids, with the
furan ring moiety at both
ends of their structures
48
2-furanone moiety
furan ring moiety
O
O
O
Fig. 33 Structure of
furospongolide (48), which
possesses one furan ring
moiety and one 2-furanone
moiety at the ends of the
molecule
20
T. Mitsuhashi and I. Abe