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Biomedical subjects

C Djerassi

Publications and source records attributed to C Djerassi.

At least 55 records · Page 3Linked to original sources
PubMed1985

New natural 2-acetoxy fatty acids using chemical ionization and electron impact mass spectrometry.

The phospholipids of the sponge Polymastia gleneni contain saturated long chain (C22-30)-acetoxy fatty acids. Their structures were assigned based on chromatographic and spectrometric data as well as comparison with a synthetic sample. The use of capillary gas chromatography combined with chemical ionization and electron impact mass spectrometry was instrumental in the eludication of structures, since only a very small amount of crude lipids was available.

Acetates↗
PubMed1984

On the origin of terpenes in symbiotic associations between marine invertebrates and algae (zooxanthellae). Culture studies and an application of 13C/12C isotope ratio mass spectrometry.

13C/12C ratios of sets of compounds, algal sterols and terpenes, isolated from dinoflagellate symbiont (zooxanthellae)-bearing soft corals and gorgonians were determined. In most cases, a significant difference was found between the delta 13C values of the terpenes and of the algal sterols from the same set, the algal sterols containing less 13C than the terpenes. These results can only be explained if terpenes are synthesized by the host. Cultured zooxanthellae, isolated from symbiotic associations, do not make terpenes. Algal sterols of the various sets do not all have the same delta 13C value: average values range from -18.2 to -24.3%. A consistent difference of about 7% in the delta 13C values of sterols of cultured symbionts isolated from two of the gorgonians was found. This has potential applications for the taxonomy of zooxanthellae, most of which are believed by some specialists to be one discrete species.

Animals↗
PubMed1984

Phospholipid studies of marine organisms: new branched fatty acids from Strongylophora durissima.

The phospholipids of the sponge Strongylophora durissima were analyzed. The major phospholipids present were phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylglycerol (PG) and phosphatidylinositol (PI). The major fatty acid components of the phospholipids consisted of short chain (C14-C19) and very long chain (C25 -C30) "Demospongic" acids. Three novel branched delta 5 monounsaturated acids, Z-19-methyl-5-pentacosenoic, Z-19-methyl-5-hexacosenoic and Z-19-methyl-5-heptacosenoic acids were encountered in the sponge. The 3-saturated counterparts of these compounds, 19-methylpentacosanoic, 19-methylhexacosanoic and 19-methylheptacosanoic acids, as well as 19-methyltetracosanoic and 20-methyloctacosanoic acids also are hitherto undescribed acids present in the sponge. Trace amounts of 2 very long chain acids also were detected and their structures tentatively assigned as 19,21-dimethylheptacosanoic and 20,22-dimethyloctacosanoic acids. The distribution of these fatty acids according to phospholipid head groups also was described.

Animals↗
PubMed1983

Minor and trace sterols in marine invertebrates 47. A re-investigation of the 19-nor stanols isolated from the sponge Axinella polypoides.

The aim of this research was to establish the true composition of the 19-nor stanols isolated from the sponge Axinella polypoides and to determine accurate stereochemistry for each 19-nor stanol isolated. The following new 19-nor stanols were collected from this sponge: (i) (22E,24S)-24-methyl-19,27-bisnor-5 alpha-cholest-22-en-3 beta-ol, (ii) (22R,23R)-22,23-methylene-19-nor-5 alpha-cholestan-3 beta-ol, (iii) (24 xi)-24-propyl-19-nor-5 alpha-cholestan-3 beta-ol and (iv) (23R,24R)-23,24-dimethyl-19-nor-5 alpha-cholestan-3 beta-ol. The general structure and stereochemistry of all fifteen 19-nor stanols were established by analysis of the MS and H-NMR (300 MHz, CDCl3) data measured for each compound. The relative percentage of 19-nor stanols having delta 22 double bonds should be sufficient to suggest that this sponge could be a potential source of starting material for the partial synthesis of certain oral contraceptives, which also have a 19-nor steroid nucleus.

Animals↗
PubMed1983

Occurrence and seasonal variation of 19-norcholest-4-en-3-one and 3 beta-monohydroxy sterols in the Californian gorgonian, Muricea californica.

The first natural occurrence of 19-norcholestenone is reported, together with 17 sterols and one other delta 4-3-ketone in the extracts of the Californian gorgonian, Muricea californica (Aurivillius). Six additional demethyl sterols and five additional 4-monomethyl sterols which remain unidentified were also detected. Lipid extracts of M. californica from a winter and summer collection were split by various chromatographic methods into free sterol, steryl ester, and steryl conjugate fractions. Sterol compositions (determined by CG and CG-MS) of each fraction, subsequent to hydrolysis, are tabulated and discussed with respect to plausible origins of observed variations. The possible relationship of the Muricea 19-nor-steroidal ketone to other naturally occurring 19-nor-steroids is discussed.

Animals↗
PubMed1983

Long-acting contraceptive agents: design of the WHO Chemical Synthesis Programme.

The great demand for improved long-acting injectable steroid contraceptives, particularly in developing countries, and the relative lack of interest from the pharmaceutical industry to develop such products stimulated WHO to launch a synthetic and screening programme to find improved, safe and acceptable injectable preparations. More than 210 esters of norethisterone (17 alpha-ethynyl-17 beta-hydroxyestr-4-en-3-one) and levonorgestrel (D-(-)-13 beta-ethyl-17 alpha-ethynyl-17 beta-hydroxygon-4-en-3-one) have been prepared in university-based research laboratories situated mainly in developing countries, and then screened by NICHHD in animal models. The following three compounds, levonorgestrel butanoate, cyclopropylcarboxylate and cyclobutylcarboxylate, proved to be particularly long-acting when administered as microcrystalline suspensions. The overall strategy of this research and development programme is described.

Animals↗
PubMed1983

Marine 4-methyl sterols: synthesis of C-24 epimers of 4 alpha, 24-dimethyl-5 alpha-cholestan-3 beta-ol and 360 MHz 1HNMR comparisons to the natural product from Plexaura homomalla.

Comparison of the highfield 1HNMR spectrum of 4 alpha, 24-dimethyl-5 alpha-cholestan-3 beta-o1 isolated by open column adsorptive chromatography and reversed-phase HPLC from P. homomalla with those of the corresponding synthetic 24 alpha and 24 beta compounds demonstrate that the gorgonian natural product is purely 24 beta, the same C-24 configuration found in sterols related to dinosterol and gorgosterol. 360 MHz 1HNMR data are also reported for synthetic 4 alpha, 24 beta-dimethyl-5 alpha-cholest-22E-en-3 beta-o1 (another P. homomalla natural product). The use of 1HNMR correlations in assigning C-24 configurations of 24-methyl marine sterols possessing various nuclei is examined and discussed. Analyses of the methyl sterol components of P. homomalla are tabulated and discussed with regard to origin and plausible biosynthetic interrelationships in light of the C-24 configurational findings.

Animals↗
PubMed1982

Sterols of the cultured dinoflagellate Pyrocystis lunula.

Eighteen components of the sterol fraction of Pyrocystis lunula have been identified. In addition to 4 alpha-methyl sterols (typical dinoflagellate sterols), regular sterols, both with a saturated and delta 5-unsaturated skeleton, were isolated, together with delta 4-3-keto steroids including the hitherto unknown 23,24R-dimethyl-4,22E-cholestadien-3-one.

Animals↗
PubMed1980

Injectable contraceptive synthesis: an example of international cooperation.

Since many contraceptives appropriate for use in developing countries are not of major interest to the pharmaceutical companies in developed countries, the World Health Organization has sponsored a program whereby contraceptives are developed outside the traditional pharmaceutical industry channels. This program might serve as a model for the develoment of other drugs or even pesticides.

Contraceptive Agents↗