D. C 29 Sterols
73
number of red algae as have Gupta and Scheuer (1969) in the coelenterate
Palythoa tuberculosa.
24
2. 24j8-ETHYLCHOLEST-5-EN-3j8-OL (CLIONASTEROL)
The 24ß-epimer of ^-sitosterol (24), on the other hand, is clionasterol
(25) and has long been considered a marine sterol. It was probably first
isolated by Dorée (1909) from the sponge Cliona celata and reisolated from
the same animal by Valentine and Bergmann (1941). Additional structural
work by Kind and Bergmann (1942) is in accord with the suggested structure.
Unfortunately there had been no recent isolation to confirm homogeneity
and structure. That caution needs to be exercised even when the work
appears ironclad was shown by Gupta (1967) who examined the sterols of
the sponge Halichondria magnicanulosa and showed that the mixture consisted of cholesterol, brassicasterol, and 24f-methyleholesterol, whereas
according to Bergmann (1962) this genus of sponges is said to elaborate
cholesterol or cholestanol.
25
3. 24£-ETHYLCHOLEST-7-EN-3/S-OL
Although the A
7 -analog of clionasterol (25) and/or ^-sitosterol (24) has
apparently not been isolated as a molecular entity, its occurrence has been
demonstrated by deSouza and Nes (1968) in the blue-green alga Phormidium
luridum. The crystalline sterol mixture isolated from the cultured algae was
73
number of red algae as have Gupta and Scheuer (1969) in the coelenterate
Palythoa tuberculosa.
24
2. 24j8-ETHYLCHOLEST-5-EN-3j8-OL (CLIONASTEROL)
The 24ß-epimer of ^-sitosterol (24), on the other hand, is clionasterol
(25) and has long been considered a marine sterol. It was probably first
isolated by Dorée (1909) from the sponge Cliona celata and reisolated from
the same animal by Valentine and Bergmann (1941). Additional structural
work by Kind and Bergmann (1942) is in accord with the suggested structure.
Unfortunately there had been no recent isolation to confirm homogeneity
and structure. That caution needs to be exercised even when the work
appears ironclad was shown by Gupta (1967) who examined the sterols of
the sponge Halichondria magnicanulosa and showed that the mixture consisted of cholesterol, brassicasterol, and 24f-methyleholesterol, whereas
according to Bergmann (1962) this genus of sponges is said to elaborate
cholesterol or cholestanol.
25
3. 24£-ETHYLCHOLEST-7-EN-3/S-OL
Although the A
7 -analog of clionasterol (25) and/or ^-sitosterol (24) has
apparently not been isolated as a molecular entity, its occurrence has been
demonstrated by deSouza and Nes (1968) in the blue-green alga Phormidium
luridum. The crystalline sterol mixture isolated from the cultured algae was