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C Djerassi

Publications and source records attributed to C Djerassi.

At least 73 records · Page 4Linked to original sources
PubMed1980

Minor and trace sterols in marine invertebrates XVII. (24R)-24,26-Dimethylcholesta-5,26-dien-3 beta-OL, a new sterol from the sponge Petrosia ficiformis.

More than thirty monohydroxy sterols were detected in the marine sponge Petrosia ficiformis, ranging from the ubiquitous 24-norcholesta-5,22-dien-3 beta-ol to the C30 sterol, 24-propylidenecholesterol. A new minor sterol was isolated and shown by spectral analysis and comparison with a synthetic sample to be (24R)-24,26-dimethylcholesta-5,26-dien-3 beta-ol [26(29)-dehydroaplysterol] (12).

Animals↗
PubMed1980

Isolation of two new C30 sterols, (24E)-24-N-propylidenecholesterol and 24 epsilon-N-propylcholesterol, from a cultured marine Chrysophyte.

Two new sterols, (24E)-24-n-propylidenecholesterol and 24 epsilon-n-propylcholesterol, were isolated from a cultured marine Chrysophyte. Since most of the steroids found in marine invertebrates are unchanged or modified sterols of algal or symbiotic origin, the discovery of these two unusual sterols in a unicellular alga grown under well-defined conditions contributes to our knowledge of sterols in marine food chains and offers a potential substrate for biosynthetic labeling experiments.

Chemical Phenomena↗
PubMed1980

Magnetic circular dichroism analysis of the IHP effect on spin equilibria in human ferric hemoglobins.

Magnetic circular dichroism (MCD) spectroscopy has been to explore the connection between optical spectra and the high spin population of several hemoglobins under various conditions. It is found that the effectiveness of IHP in inducing spectral changes can be markedly affected by solvent. For example, the IHP-induced spectral changes in the visible region for nitritomethemoglobin-A in mixed buffer solvent systems (glycerol or polyethylene glycol (PEG), mw 190-210) are more than double those observed in aqueous buffers. We estimate that IHP induces a mix of R/T forms in bis-tris phosphate buffers, for NO-2metHb that is only about 50%. While PEG and glycerol both lead to enhanced IHP-induced spectral differences, they behave differently in two aspects. PEG shifts the visible MCD and absorption spectra of F-metHb-A, supposedly already biased towards the T form by ligand, in the same direction that IHP does. PEG also maximizes the spin state changes with IHP for three R from hemoglobins and N-3metHb-A, and so appears to stabilize the T form in all cases. Glycerol does not. In addition, the apparent binding constant for NO-2 to H2OmetHb-A differs between these two solvents. Comparison of the data from several hemoglobins leads to the conclusion that the changes in spin state distributions induced by IHP correlate well with quaternary structure for a given hemoglobin. An analogous correlation amongst various proteins between initial spin state distribution (IHP) absent) and quaternary structure is not found.

Circular Dichroism↗
PubMed1980

Synthesis and biochemical screening of phenylselenium-substituted steroid hormones.

The syntheses of phenylselenium-substituted progesterone [21- (1) and 17 alpha-(phenylseleno)progesterone (2)] and testosterone [16 beta- (3) and 16 alpha-(phenylseleno)testosterone (4)] derivatives are described, along with data which help to establish the stereochemistry of the substituents in the testosterone molecules. Except for 21-(phenylseleno)-progesterone, the molecules exhibit greatly reduced receptor-binding capabilities.

Animals↗
PubMed1979

Side chain-hydroxylated sterols of the red alga Asparagopsis armata: significant products or artifacts due to autoxidation?

Sterols characterized by an allylic hydroxyl group in the side chain, such as stigmasta-5,28-diene-3 beta, 24 epsilon-diol (1), cholesta-5,23-diene-3 beta,25-diol (2) and cholesta-5,25-diene-3 beta,24 epsilon-diol (3), have been identified several times in various marine algae. Their origin was considered as doubtful: they could have been bona fide constituents of the alga, or be artifacts caused by autoxidation during the isolation process. We have shown that the dihydroxy steroids 2 and 3 can indeed be produced by the autoxidation of cholesta-5,24-dien-3 beta-ol (desmosterol) (5), but that they are nevertheless present in the taxonomic significance.

Cholestadienols↗
PubMed1978

Minor and trace sterols in marine invertebrates V. Isolation, structure elucidation and synthesis of 3beta-hydroxy-26,27-bisnorcholest-5-en-24-one from the sponge Psammaplysilla purpurea.

The free sterol mixture of the sponge Psammaplysilla purpurea was shown to contain aplysterol as the major constituent. In addition to other sterols such as 5,7-cholestadien-3beta-ol, cholesterol, 5alpha-cholestan-3beta-ol, 24epsilon-methylcholesta-5,22-dien-3beta-ol, 24epsilon--methylcholesterol, 24epsilon-ethylcholesta-5,22-dien-3beta-ol and 24,28-dehydroaplysterol, a new minor sterol was isolated and shown by spectral analysis as well as partial synthesis to be 3beta-hydroxy-26,27-bisnorcholest-5-en-24-one. The sterol mixture contains no other short side chain or 24-keto sterols except for small amounts of 3beta-hydroxypregn-5-en-20-one and 3beta-hydroxy-5alpha-pregnan-20-one.

Animals↗