D. C 29 Sterols
77
33
9. 28-ISOFUCOSTEROL (A
5 -AVENASTEROL)
Tsuda and Sakai (1960) examined the sterols of the green alga Enteromorpha lima and isolated an homogeneous sterol to which they assigned
structure 32 on the basis of comparison of physical constants with those
published for A
5 -avenasterol. A
5 -Avenasterol had been isolated by Idler et al.
(1953) from oat seeds and was inadvertently synthesized by Dusza (1960)
who attempted to synthesize the geometrical isomer fucosterol. More recently Gibbons et al. (1968) isolated 28-isofucosterol (32) as the principal
sterol in the green algae Enteromorpha intestinalis and Ulva lactuca.
28
(
32
10. 24-ETHYLCHOLESTA-5,28(29)-DIEN-3£,24£-DIOL (SARINGOSTEROL)
The first dihydroxy steroid to be isolated from a marine source is saringosterol (33), which Ikekawa et al. ( 1966) discovered as a minor sterol in the brown
algae Sargassum ringgoldianum and Dictyopteris divaricata. Its structure was
determined by spectroscopic methods and by partial synthesis from 24oxocholesterol via ethynylation and partial hydrogénation. In a footnote, the
authors mention the absence of sargasterol (fucosterol was the major sterol)
in S. ringgoldianum and suggest that it might be caused by seasonal variation.
In their quantitative examination of nine species of brown algae Ikekawa
et al. (1968) detected saringosterol varying from a trace in Sargassum thunbergii to 8% in Sargassum confusum. Patterson (1968) found saringosterol
(4%) along with fucosterol (74%) and 24-methylenecholesterol (20%) in
brown algae of the genus Laminaria.
77
33
9. 28-ISOFUCOSTEROL (A
5 -AVENASTEROL)
Tsuda and Sakai (1960) examined the sterols of the green alga Enteromorpha lima and isolated an homogeneous sterol to which they assigned
structure 32 on the basis of comparison of physical constants with those
published for A
5 -avenasterol. A
5 -Avenasterol had been isolated by Idler et al.
(1953) from oat seeds and was inadvertently synthesized by Dusza (1960)
who attempted to synthesize the geometrical isomer fucosterol. More recently Gibbons et al. (1968) isolated 28-isofucosterol (32) as the principal
sterol in the green algae Enteromorpha intestinalis and Ulva lactuca.
28
(
32
10. 24-ETHYLCHOLESTA-5,28(29)-DIEN-3£,24£-DIOL (SARINGOSTEROL)
The first dihydroxy steroid to be isolated from a marine source is saringosterol (33), which Ikekawa et al. ( 1966) discovered as a minor sterol in the brown
algae Sargassum ringgoldianum and Dictyopteris divaricata. Its structure was
determined by spectroscopic methods and by partial synthesis from 24oxocholesterol via ethynylation and partial hydrogénation. In a footnote, the
authors mention the absence of sargasterol (fucosterol was the major sterol)
in S. ringgoldianum and suggest that it might be caused by seasonal variation.
In their quantitative examination of nine species of brown algae Ikekawa
et al. (1968) detected saringosterol varying from a trace in Sargassum thunbergii to 8% in Sargassum confusum. Patterson (1968) found saringosterol
(4%) along with fucosterol (74%) and 24-methylenecholesterol (20%) in
brown algae of the genus Laminaria.