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1.
WhenChlorella emersonii, a green alga, was cultured in the presence of 20 ppm AY-9944, a number of sterols accumulated which appear to be intermediates
of sterol biosynthesis in this organism. The sterols isolated include 14α-methyl-ergost-8-en-3β-ol, 14α-methyl 24S-stigmast-8-en-3β-ol,
14α-methyl ergosta-8,24(28)-dien-3β-ol and 4α, 14α-dimethyl 24S-stigmast-8-en-3β-ol. Smaller quantities of several other sterols
were found in addition to the normally occurring Δ7, chondrillasterol and Δ7. Control cultures were found to contain, in addition to the normally occurring sterols, smaller quantities of most of the
sterols isolated from AY-9944 inhibited cultures. AY-9944 is a specific inhibitor of Δ7 in cholesterol biosynthesis in animals. However, sinceC. emersonii terminates sterol biosynthesis one step prior to the Δ7 step, AY-9944 apparently inhibits sterol biosynthesis prior to this step in this organism. The accumulation of 14α-methyl
sterols in treated cultures suggests that AY-9944 is an effective inhibitor of the 14α-methyl removal inC. emersonii.
Scientific Article No. A1865, Contribution No. 4775 of the Maryland Agricultural Experiment Station. 相似文献
2.
WhenChlorella ellipsoidea was grown in the presence of 4 ppm AY-9944, complete inhibition of Δ5-sterol biosynthesis was achieved. However total sterol production remained unaltered. As a result a number of sterols accumulated
that appear to be intermediates in sterol biosynthesis. These sterols were described and identified as (24S)-5α-ergost-8(9)-en3β-ol,
(24S)-5α-stigmast-8(9)-en-3β-ol, 4α-methyl-(24S)-5α-ergosta-8, 14-dien-3β-ol, 4α-methyl-(24S)-5α-stigmasta-8, 14-dien-3β-ol,
4α-methyl-(24S)-5α-ergost-8(9)-en-3β-ol and (24S)-4α-methyl-5α-stigmast-8(9)-en-3β-ol. The occurrence of these sterols inChlorella ellipsoidea is the first time they have been noted in biological material. The accumulation of these sterols in treated cultures indicates
that AY-9944 is an extremely effective inhibitor of the Δ8→Δ7 isomerase and the Δ14 reductase of these plants. The occurrence of small amounts of other sterols in treated cultures has led to a proposed pathway
for thebiosynthesis of sterols inChlorella ellipsoidea.
Scientific Article No. A1775, Contribution No. 4565 of the Maryland Agricultural Experiment Station. 相似文献
3.
The rat liver enzyme system, which catalyzes reduction of Δ5,7,24-cholestatrien-3β-ol to cholesterol (Δ5-cholesten-3β-ol), converted radiolabeled Δ5,7,22-cholestatrien-3β-ol to Δ5,22-cholestadien-3β-ol, but not to cholesterol. This enzyme system thus contains membrane-bound Δ7 and Δ24-reductases and no Δ22-reductase. Kinetic and competition studies showed that the enzymes system contains a single Δ5,7-sterol Δ7-reductase, which is not influenced by unsaturtion at the Δ22-position of the sterol side chain. The identity of Δ5,22-cholestadienol was established by chromatographic, spectral and chemical analyses. Use of the enzyme system and readily available
Δ5,7,22-cholestatrienol provides a facile procedure for specific production of Δ5,22-cholestradien-3β-ol in quantity. 相似文献
4.
Sterols constitute 1.95% of the total extractable lipids ofAcheta domesticus L., of which 18% are esterified. The free sterols consist of cholestane-3β-ol (0.5%), Δ5-cholestene-3β-ol (83.5%), Δ7-cholestene-3β-ol (2.3%) Δ5,7-cholestadiene-3β-ol (3%), Δ5,22-cholestadiene-3β-ol (4%), Δ5,7,22-cholestatriene-3β-ol (0.2%), campestane-3β-ol (0.03%), Δ5-campestene-3β-ol (1.0%), Δ7-campestene-3β-ol (trace), Δ5,7-campestadiene-3β-ol (0.2%), stigmastane-3β-ol (0.09%), Δ5-stigmastene-3β-ol (2.1%), Δ7-stigmastene-3β-ol (0.04%), Δ5,7-stigmastadiene-3β-ol (0.4%), Δ5,22-stigmastadiene-3βol (0.1%). The same sterols are present in the esterified sterol fraction. Δ7-Sterols and Δ5,7-sterols are present in significantly larger amounts in the esterified fraction than in the free sterol fraction. By a comparison
with the sterols of the cricket food, it is clear thatA. domesticus is capable of removing methyl and ethyl groups from C-24 of sterols of the campestane and stigmastane type. The ability to
introduce a Δ7 double bond into saturated and Δ5-sterols is indicated, and it is suggested that Δ7-sterols of the C27, C28, and C29 sterol series may be intermediates in the conversion of Δ5-sterols to Δ5,7-sterols.
Associate Professor, Department of Chemistry, University of Michigan, Ann Arbor, Mich.; Alfred P. Sloan Foundation Fellow,
1968–68.
Public Health Service Predoctoral Fellow, 1968–67. 相似文献
5.
Inhibitors of cholesterol biosynthesis AY 9944 and 20,25 diazacholesterol were administered by stomach tube to suckling rats
in varying doses during the time of rapid myelination (15–22 days of age). Purified myelin was prepared from the brains and
spinal cords, and the sterol content analyzed. Up to 50% of the myelin sterol consisted of desmosterol in rats treated with
20,25 diazacholesterol, while 7-dehydrocholesterol comprised at least one third of the myelin sterol in rats administered
AY 9944. Myelin from rats treated with both compounds contained desmosterol, 7-dehydrocholesterol, Δ5,7,24 cholestatriene-3-β-ol and an unknown sterol, the four comprising about 45% of the total sterol. The proportion of phospholipid:
galactolipid-total sterol in myelin from the drug-treated rats was not significantly different from the normal, although much
less myelin was recovered. Brain and spinal cord slices from 22 to 25-day rats pretreated with inhibitors showed decreased
uptake of U-14C-glucose into all myelin components. The decreased uptake was approximately proportional in all lipids and the protein was
also affected. It is proposed that myelin composition is fixed, and that a deficiency of one of the lipid components will
limit the assembly of the whole lipid portion of the membrane.
Presented at the AOCS Meeting, San Francisco, April 1969. 相似文献
6.
Sterol excretion in the spontaneously atherosclerosis-susceptible White Carneau (WC) pigeon, the Silver King (SK) pigeon and
the Show Racer (SR) pigeon was studied by thin layer chromatography (TLC), argentation TLC and gas liquid chromatography.
Unlike man and the chicken, these pigeons excreted no coprostanol or coprostanone derivatives of sterols. Moreover incubation
of14C-labeled cholesterol with pigeon feces indicated that, also unlike man and the chicken, these pigeons are unable to convert
it to coprostanol. Bacteriologic examination revealed the absence of gram-negative anaerobic flora and of members of the genusBifidobacterium in both the WC and SR pigeons. On the other hand, one of the two SK pigeons examined showed evidence of the presence of bothBacteroids fragilis andB. bifidum in the upper intestinal tract. Although no qualitative experiments were performed, no unusual characteristics of the aerobic
flora were noted in these pigeons. In addition, analysis of human stool specimens indicated a “normal” bowel flora. The flora
of the intestinal tract of the chicken is similar to that of the human. Because of this similarity, it appears that differences
in environment (living conditions, diets) between the human and the chicken are of little consequence. The results obtained
in this study suggest the possibility that the anaerobic gram-negative flora and sponsible, at least in part, for the chemical
conversion of cholesterol to coprostanol.
Presented in part at the Fourth International Symposium on Drugs Affecting Lipid Metabolism, Philadelphia, September 1971,
and at the AOCS Meeting, Los Angeles, April 1972.
The following nomenclature has been used for the steroids referred to in this paper: cholesterol, cholest-Δ5-en-3β-ol; coprostanol, 5β-cholestan-3β-ol; campesterol, 24-methylcholest-Δ5-en-3βol; stigmasterol, 24-ethylcholest-Δ5,22-dien-3β-ol; β-sitosterol, 24-ethylcholest-Δ5-en-3β-ol; coprocampestanol, 24-methyl-5β-cholestan-3β-ol; coprostigmastenol, 24-ethyl-5β-cholest-Δ22-en-3β-ol; coprostigmastanol, 24-ethyl-5β-cholestan-3β-ol; coprostanone, 5β-cholestan-3-one; campestanone, 24-methyl-5β-cholestan-3-one;
stigmastenone, 24-ethyl-5β-cholest-Δ22-en-3-one; and β-sitostanone, 24-ethyl-5β-cholestan-3-one. 相似文献
7.
Campesterol ([24R]-24-methyl-5-cholesten-3β-ol) was isolated from a soybean sterol mixture and purified on a small scale by
column chromatography and on a large scale by crystallization from acetone to 97% purity. From this, 7-dehydrocampesterol
([24R]-24-methyl-5,7-cholestadien-3β-ol) and campestanol ([24R]-24-methyl-cholestan-3β-ol) were prepared. The acetates and
benzoates of all four compounds also were obtained and compared to the corresponding members of the ergostane series.
Contribution 2189, Arizona Agricultural Experiment Station. 相似文献
8.
Oysters (Crassostrea gigas) contain at least 8 predominant sterols as determined by gas liquid chromatography and a modified Liebermann-Burchard reaction.
These sterols and the average amount found in mg/100 are: C26-sterol (22-trans-24-norcholesta-5, 22-diene-3β-ol), 19.1; 22-dehydrocholesterol, 15.1; cholesterol, 46.8; brassicasterol, 27.2; Δ5,7-sterols (i.e., 7-dehydrocholesterol) 22.5; 24-methylenecholesterol 29.1; 24-ethylcholesta-5,22-diene-3β-ol, 1.2; and 24-ethylcholesta-5-en-3β-ol,
12.7. The distribution of these sterols appears uniform (r2=0.938) between 5 major organs of the oyster. The percent body mass vs percent total sterols in these 5 organs are: mantle
44.1–41.4; visceral mass 30.3–36.7; gills 13.2–11.7; adductor muscle 8.3–3.7; and labial palps 4.2–6.5. The possible sources
of these sterols are discussed. 相似文献
9.
The 4-desmethylsterols from the leaves ofBeta vulgaris are a mixture of Δ7-sterols (71%) and Δ5-sterols (29%). The Δ7-sterols isolated are spinasterol (24α-ethylcholesta-7,22-dien-3β-ol; 45%), 22-dihydrospinasterol (24α-ethylcholest-7-en-3β-ol;
24%), and avenasterol (24-ethylcholesta-7,24(28)-dien-3β-ol; 1.5%). The Δ5-sterols isolated are sitosterol (24α-ethylcholest-5-en-3β-ol; 15%), 24ζ-ethylcholesta-5,22-dien-3β-ol (7.5%), and 24ζ-methylcholest-5-en-3β-ol
(7%). 相似文献
10.
Sterols were analyzed from four phytoplankton strains which are under investigation as possible sources of food for oysters
in culture. One strain ofPyramimonas contained only 24-methylenecholesterol as a major sterol component.Pyramimonas grossii, Chlorella autotrophica andDunaliella tertiolecta each contained a complex mixture of C28 and C29 sterols with Δ7, Δ5,7 and Δ5,7,9(11) nuclear double bond systems. Sterols were found both with and without the C-22 side chain double bond. Ergosterol and 7-dehydroporiferasterol
were the principal sterols in each of the latter three species, which also contained the rare tetraene sterols, 24-methylcholesta-5,7,9(11),22-tetraen-3β-ol
and 24-ethylcholesta-5,7,9(11),22-tetraen-3β-ol. 相似文献
11.
The predominant 4-desmethylsterols from the leaves of 13 species in eight genera of the family Chenopodiaceae are 24α-ethylsterols.
In four species,Chenopodium ambrosioides L.,C. rubrum L.,Salicornia europaea L. andS. bigelovii Torr., the C-22(23) double bond is introduced into more than 70% of the 24α-ethylsterols producing spinasterol (24α-ethylcholesta-7,22E-dien-3β-ol)
in the first two species and mixtures of spinasterol and stigmasterol (24α-ethylcholesta-5,22E-dien-3β-ol) in the latter species.
The saturated side chain analogues predominate with more than 70% of the 24α-ethylsterols in eight species.Salsola kali L.,Suaeda linearis (Ell.) Moq.,Kochia scoparia (L.) Roth., andBassia hirsute (L.) Aschers. synthesize sitosterol (24α-ethylcholest-5-en-3β-ol), andAtriplex arenaria Nutt.,C. album L.,C. urbicum L. andC. leptophyllum Nutt. possess mixtures of sitosterol and 22-dihydrospinasterol (24α-ethylcholest-7-en-3β-ol). Sitostanol (24α-ethyl-5α-cholestan-3β-ol)
was isolated fromSuaeda linearis as an 18% component of the total 4-desmethylsterol and in lesser amounts from four other species. In all species synthesizing
24-ethyl-Δ5-sterols, a 24ξ-methylcholest-5-en-3β-ol was also present at 1.0–20% of the total 4-desmethylsterol. Avenasterol [24-ethylcholesta-7,24(28)Z-dien-3β-ol],
isofucosterol [24-ethylcholesta-5,24(28)Z-dien-3β-ol), cholesterol (cholest-5-en-3β-ol) and 24ξ-methyl-5α-cholestan-3β-ol
also were isolated from several species. Species in the family Chenopodiaceae and the type genusChenopodium may be categorized into one of three groups based on sterol biosynthesis: the Δ7-sterol producers; the Δ5-sterol producers, and those producing mixtures of both Δ7- and Δ5-sterols in relatively fixed percentage compositions. 相似文献
12.
Nikolaus Weber 《Lipids》1988,23(1):42-47
[4-14C]Sitosteryl β-D-glucoside, intragastrically administered to rats, was not absorbed by the intestinal mucosa. At three hr
after the application, radioactivity was concentrated almost exclusively in the digesta of stomach, small intestine as well
as cecum and colon, whereas only low proportions of radioactively labeled compounds were found in the various tissues of the
gastrointestinal tract. Minor proportions of labeled metabolites of [4-14C]sitosteryl β-D-glucoside, such as sitosterol and sitosteryl esters, were formed in the small intestine in vivo and in slices
of small intestine in vitro. In the tissues of cecum and colon as well as the digesta derived from them, high proportions
of labeled coprositostanol, i.e. 24α-ethyl-5β-cholestan-3β-ol, that obviously had been formed by bacterial degradation of
the substrate were detected.
The feeding of sitosteryl β-D-glucoside (0.5 g/kg body weight×day) over a period of four weeks did not alter significantly
body weights or organ weights of rats. Analyses of steryl lipids of the various organs and tissues confirmed the findings
obtained with the radioactive substrate: neither sitosteryl β-D-glucoside nor sitosterol or sitosteryl esters derived therefrom
had been transported in appreciable amounts to organs and tissues outside the alimentary canal during the feeding period.
Minor proportions of unmetabolized sitosteryl β-D-glucoside were detected in the tissues of stomach and intestine, whereas
large proportions of the substrate were found in feces of rats that had received the sitosteryl β-D-glucoside-containing diet;
coprositostanol was found in feces of these animals in high proportions as well. Thus, the use of sitosteryl β-D-glucoside
as emulsifier or preservative in food and feed does not appear to involve any risk.
The systematic nomenclature of the sterols referred to by trivial names is, cholest-5-en-3β-ol (cholesterol); 5α-cholestan-3β-ol
(5α-cholestanol); 5β-cholestan-3β-ol (5β-cholestanol, coprostanol); 24α-methylcholest-5-en-3β-ol (campesterol); 24α-methyl-5α-cholestan-3β-ol
(5α-campestanol); 24α-methyl-5β-cholestan-3β-ol (5β-campestanol, coprocampestanol); 24α-methyl-cholesta-5,22-dien-3β-ol (brassicasterol);
24α-ethylcholest-5-en-3β-ol (sitosterol, β-sitosterol); 24α-ethyl-5α-cholestan-3β-ol (5α-sitostanol); 24α-ethyl-5β-cholestan-3β-cholestan-3β-ol
(5β-sitostanol, coprositostanol); 24α-ethylcholesta-5,22-dien-3β-ol (stigmasterol). 相似文献
13.
The major sterols of the seeds ofBenincasa cerifera, Cucumis sativus, Cucurbita maxima, C. pepo andTrichosanthes japonica and of the mature plant tissues (leaves and stems) ofCitrullus battich, Cucumis sativus andGynostemma pentaphyllum of the family Cucurbitaceae were 24-ethyl-Δ7-sterols which were accompanied by small amounts of saturated and Δ5-and Δ8-sterols. The 24-ethyl-Δ7,22,Δ7,25(27) and Δ7,22,25(27)-sterols constituted the predominant sterols for the seed materials, whereas the 24-ethyl-Δ7 and Δ7,22-sterols were the major ones for the mature plant tissues. The configurations of C-24 of the alkylsterols were examined by
high resolution1H NMR and13C NMR spectroscopy. Most of the 24-methyl- and 24-ethylsterols examined which lack a Δ25(27)-bond (i.e., 24-methyl-, 24-methyl-Δ22-, 24-ethyl- and 24-ethyl-Δ22 sterols) were shown to occur as the C-24 epimeric mixtures in which the 24α-epimers predominated in most cases. The 24-ethylsterols
which possess a Δ25(27) (i.e., 24-ethyl-Δ25(27)-and 24-ethyl-Δ7,22,25(27)-sterols) were, on the other hand, composed of only 24β-epimers. The Δ8-sterols identified and characterized were four 24-ethyl-sterols: 24α-and 24β-ethyl-5α-cholesta-8,22-dien-3β-ol, 24β-ethyl-5α-cholesta-8,25(27)-dien-3β-ol
and 24β-ethyl-5α-cholesta-8,22,25(27)-trien-3β-ol. This seems to be the first case of the detection of Δ8-sterols lacking a 4-methyl group in higher plants, and among the four Δ8-sterols the latter two are considered to be new sterols. The probable biogenetic role of the Δ8-sterols and the possible biosynthetic pathways leading to the 24α- and 24β-alkylsterols in Cucurbitaceae are discussed. 相似文献
14.
Desmosterol in developing rat brain 总被引:4,自引:0,他引:4
David Kritchevsky Shirley A. Tepper Nicholas W. DiTullio William L. Holmes 《Journal of the American Oil Chemists' Society》1965,42(12):1024-1028
The brain of the young rat contains appreciable amounts of desmosterol (24-dehydrocholesterol). The peak desmosterol concentration
is seen during the first week of life and only traces of this sterol are found at 21 days. The spinal cord also contains some
desmosterol. Rat brain desmosterol is distributed in the white matter, gray matter and cerebellum and occurs in the same proportion
to cholesterol in each of these brain fractions. Rat brain contains a small amount of sterol ester but no appreciable amounts
of desmosterol are present in this fraction.
Studies carried out in intact animals injected either intraperitoneally or intracerebrally with mevalonic acid-2-14C or glucose-U-14C indicate the biosynthetic origin or brain desmosterol. Rat brain slices (1–20 day old) incubated in suitably fortified medium
convert sodium acetate-2-14C and glucose-U-14C to desmosterol, whereas brain slices from adult rats yielded no radioactive desmosterol under similar conditions. When labeled
desmosterol was incubated with young rat brain slices, it was converted to cholesterol.
When pregnant rats were treated with triparanol (20 mg/kg/day) during the course of their pregnancy, they either resorbed
the fetuses or gave birth to small, stillborn litters. The brains of the progeny of triparanol treated mothers contained large
amounts of desmosterol as well as another sterol which may be Δ7,24-cholestadiene-3β-ol. 相似文献
15.
The predominant 4-desmethylsterols from the leaves of 12 species in 11 genera of the family Caryophyllaceae are 24-ethyl-Δ7-sterols. In eight species,Scleranthus annus L.,Paronychia virginica Spreng.,Lychnis alba Mill.,Silene cucubalus Wibel,Dianthus armeria L.,Gypsophilia paniculata L.,Saponaria officinales L. andMyosoton aquaticum (L.) Moench, the major sterols are spinasterol (24α-ethylcholesta-7,22E-dien-3β-ol) and 22-dihydrospinasterol (24α-ethylcholest-7-en-3β-ol),
with spinasterol at more than 60% of the desmethylsterol in the latter six species. Both 24α-and 24β-ethyl-Δ7-sterols are present in two species,Minuartia caroliniana Walt. andSpergula arvensis L., which possess 24β-ethylcholesta-7,25(27)-dien-3β-ol and 24β-ethylcholesta-7,22E,25(27)-trien-3β-ol as well as spinasterol
and 22-dihydrospinasterol.Cerastium arvense L.,C. vulgatum L. andArenaria serpyllifolia L. possess 24-alkyl-Δ5 and Δ7-sterols. These three species synthesize sitosterol (24α-ethylcholest-5-en-3β-ol), 24ζ-methylcholest-5-en-3β-ol, spinasterol,
22-dihydrospinasterol and the stanols, sitostanol (24α-ethyl-5α-cholestan-3β-ol) and 24ζ-methyl-5α-cholestan-3β-ol. Avenasterol
(24-ethylcholesta-7,24(28)Z-dien-3β-ol) was also isolated from five species. Sterol biosynthetic capability may be a useful
characteristic in examining the taxonomic relatedness of plants in the Caryophyllaceae. 相似文献
16.
The effects of the hypocholesterolemic drug AY-9944 (trans-1,4-bis(2-chlorobenzylaminoethyl)cyclohexane dihydrochloride) at two concentrations (10−4M and 5×10−4M), on the synthesis of sterols and sterol esters bySaccharomyces cerevisiae were investigated. Although growth was not markedly affected by the drug, there was a decrease in the free sterol to sterol
ester ratio with increased drug concentration. A concomitant increase in the saturated fatty acids esterified to sterol relative
to the unsaturated fatty acids was also noted in response to increased drug concentration. Ergosterol accounted for 94.7%
of the free sterol in the control culture and for 87.8% of the 5×10−4M drug-treated culture, respectively. However, in the sterol ester fraction, the ergosterol content decreased from a value
of 45.1% in the control culture to 2.4% in the 5×10−4M AY-9944 treated culture. The sterol ester fraction simultaneously showed increased levels of the Δ8 sterol, fecosterol, in response to increased drug concentration from a 7.4% control value to 57.4% in the 5×10−4M drug-treated culture. The accumulation of the Δ8 sterol suggests that the site of action of the drug is probably at the Δ8 to Δ7 isomerase step in the biosynthesis of ergosterol. The fact that ergosterol is retained as the major free sterol suggests
a biological advantage to the retention of this particular sterol. In addition, the near normal growth in the presence of
the drug, in spite of the occurrence of an altered sterol ester profile, indicates that the composition of the sterol ester
fraction is not as critical as the free sterol fraction.
These results form a portion of a dissertation submitted to the Graduate School, University of Maryland, College Park, MD,
by Ravi Pereira, in partial fulfillment of the requirements for the Ph.D. degree in Biochemistry. 相似文献
17.
15-Aza-24-methylene-D-homocholesta-8,14-dien-3β-ol, an antimycotic agent, at a concentration of 75 ng/ml inhibited ergosterol
biosynthesis inSaccharomyces cerevisiae strain 3701 B resulting in the accumulation of an unusual sterol. Experimental data presented indicate that this sterol is
ergosta-8,14-dien-3β-ol. The accumulation of the compound is supportive of current models of biosynthetic pathways for sterols
in yeast and is consistent with inhibition by the azasterol of the Δ14 sterol reductase. 相似文献
18.
Eighteen sterols were isolated from the aerial parts ofKalanchoe pinnata (Crassulaceae) including four novel sterols,viz. (24R)-stigmasta-5,25-dien-3β-ol (24-epiclerosterol), (24R)-5α-stigmasta-7,25-dien-3β-ol, 5α-stigmast-24-en-3β-ol, and 25-methyl-5α-ergost-24(28)-en-3β-ol. 24-Epiclerosterol and its
Δ7-analog occur together with their 24S/β-epimers in the same plant making this the first report of the isolation of both C-24 epimers of Δ25-unsaturated 24-alkylsterols from a non-marine organism. Iodine-catalyzed isomerization of stigmasta-5,24-dien-3β-ol (24-ethyldesmosterol),
the main sterol ofK. pinnata, yielded 24-epiclerosterol among other products. 相似文献
19.
From the sterol fraction of seed oil from commercialCucurbita moschata Dutch (“calabacita”) Δ5 and Δ7 sterols having saturated and unsaturated side chain were isolated by chromatographic procedures and characterized by spectroscopic
(1H and13C-nuclear magnetic resonance, mass spectrometry) methods. The main components were identified as 24S-ethyl 5α-cholesta-7,22E-dien-3β-ol (α-spinasterol); 24S-ethyl 5α-cholesta-7,22E, 25-trien-3β-ol (25-dehydrochondrillasterol); 24S-ethyl 5α-cholesta-7, 25-dien-3β-ol; 24R-ethylcholesta-7-en-3β-ol (Δ7-stigmastenol) and 24-ethyl-cholesta-7, 24(28)-dien-3β-ol (Δ7,24(28)-stigmastadienol).Lipids 31, 1205–1208 (1996). 相似文献
20.
[2-3H]Cyclolaudenol was converted into α-spinasterol, 24β-ethylcholesta-7,25-dien-3β-ol and 24β-ethylcholesta-7,22,25-trien-3β-ol
by seedlings ofCucurbita maxima. As 24-methylenecycloartanol is the obligatory precursor of 24-ethylsterols, it can be assumed that the transformation of
cyclolaudenol to 24-methylenecycloartanol must have occurred. These results lead us to postulate the existence, in the Cucurbitaceae
family, of an enzymatic system capable of isomerizing Δ25 alkylsterols into Δ25(28) sterols. 相似文献