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Biomedical subjects

C Djerassi

Publications and source records attributed to C Djerassi.

At least 91 records · Page 5Linked to original sources
PubMed1976

Minor and trace sterols in marine invertebrates. 1. General methods of analysis.

3beta-Hydroxy sterols occurring at a concentration of at least 0.001% of the sterol mixtures of Pseudoplexaura porosa and Plexaura homomalla have been fractionated using a series of refined techniques and subsequently analyzed using combined gas chromatography-mass spectrometry (GC-MS) in the development of a procedure for examining the minor and trace components of marine sterol mixtures. A total of 49 sterols were found which spanned a molecular weight range of 274 to 440. In addition delta4-3-keto analogs of cholesterol, 24-methylcholesterol and gorgosterol were found in the extracts of P. homomalla. Initial separation of various natural sterol-containing conjugates and free sterols was found to have a number of advantages. Fractional digitonin precipitation and alumina column chromatography were found to possess greater sterol separation abilities than previously recognized. Many of the minor sterols were found to possess novel structures including a series of short side chain sterols, 19-nor sterols, 5beta-stanols and 4-monomethyl sterols for which structure elucidation work is continuing.

Animals↗
PubMed1976

Magnetic circular dichroism of ferrous carbonyl adducts of cytochromes P-450 and P-420 and their synthetic models: further evidence for mercaptide as the fifth ligand to iron.

Absorption and magnetic circular dichroism (MCD) spectra have been obtained for the ferrous carbonyl adducts of cytochromes P-450 and P-420 as well as synthetic model systems. Ferrous porphyrins with sodium methyl mercaptide and CO in benzene give MCD and absorption spectra which are almost identical to those of the natural enzyme, indicating that in P-450 a mercaptide serves as the fifth ligand in the ferrous carbonyl adduct. MCD spectra of models with either propyl mercaptan or N-methylimidazole as the axial ligand are identical with that of P-420. Thus, no unambiguous assignment of the axial ligand can be made in this case. The infrared stretching frequencies of ferrous porphyrin carbonyl complexes and the absorption spectrum of the CO adduct of Na[Fe1(meso-tetraphenylporphyrin dianion)] are consistent with the concept that in P-450 considerable electron density is transferred to the iron by the mercaptide ligand.

Circular Dichroism↗
PubMed1975

24xi-Methylcholestane-3beta, 5alpha, 6beta, 12beta, 25-pentol 25-monoacetate, a novel polyoxygenated marine sterol.

24xi--Methylcholestane-3beta, 5alpha, 6beta, 12beta, 25-pentol 25-monoacetate has been isolated from an Alyconarian and its structure was established in part through extensive high resolution mass spectral and nmr studies and partly through the nonidentity of one of its degradation products with 24xi-methylcholestane-3beta, 5alpha, 6beta, 12alpha-tetrol synthesized from deoxycholic acid.

Animals↗
PubMed1975

Mass spectrometry in structural and stereochemical problems CCXLV. [1] The electron impact induced fragmentation reactions of 17-oxygenated progesterones.

The mass spectral fragmentation of a number of 17alpha-hydroxy-, 17alpha-acetoxy-, and 17alpha-methoxyprogesterones have been examined. Unlike other steroidal delta4-3-ketones, fragmentation reactions associated with the alpha,beta-unsaturated ketonic function are not particularly significant; rather, abundant ions are formed by decomposition processes occurring in and around ring D. Reactions of diagnostic significance include complete or partial loss of ring D, and elimination of the C-17 side chain (CH3CO), followed by loss of the C-17 oxygen function together with a hydrogen atom (H2O, CH3COOH, CH3OH).

Hydroxyprogesterones↗
PubMed1974

Insect control of the future: operational and policy aspects.

uman and insect population control have several features in common, all of them indicating that the lag times in converting laboratory discoveries into practical agents are increasing greatly and that ROI calculations are becoming more and more significant in decisions related to the development of new agents. ROI calculations are particularly important in the field of insect control because, by being more specific, the agents of the future are likely to cover smaller markets. Several recommendations for stimulating the development of new methods of insect control are proposed which are addressed primarily to policy-makers. If they are not implemented, then our suggestions should at least stimulate others to make alternative proposals. If neither event occurs, then it is unlikely that there will be any fundamentally new approaches to practical insect control in this decade; a similar prediction (6) that was made 4 years ago in the field of human birth control is rapidly proving to be correct.

Animals↗
PubMed1974

Reinvestigation of the proton resonance spectrum of vindolinine at 300 MHz.

A reinvestigation of the proton resonance spectrum of vindolinine based on new data at 300 MHz is now completely consistent with the recently modified structure. These data are presented as an example of possible pitfalls in the interpretation of complex spectral data for structural analysis. Spectra and assignments are included.

Indoles↗
PubMed1974

Magnetic circular dichroism studies XXXV. A comparison of cytochromes P-450 and P-448.

Cytochromes P-450 and P-448 in microsomal suspensions have been shown to be spectrally distinct by magnetic circular dichroism spectroscopy. Furthermore, this technique can be used to measure induction of these two cytochromes by phenobarbital and 3-methyl-cholanthrene. Magnetic circular dichroism spectroscopy is thus at least as useful as difference spectroscopy for the investigation of P-450 and P-448 and more informative because the presence of cytochrome b(5) and hemoglobin can be detected concurrently. We have also shown that the molar magnetic ellipticity for reduced + CO treated cytochrome P-450 of Pseudomonas grown on camphor is of similar value to that of reduced + CO treated microsomal P-450 and P-448.

Circular Dichroism↗
PubMed1974

Magnetic circular dichroism studies. XXV. A preliminary investigation of microsomal cytochromes.

The application of magnetic circular dichroism as an optical probe for simultaneous identification and determination of at least two microsomal cytochromes is demonstrated. The assignments of the bands in the spectra of microsomal suspensions are made from the spectra of soluble preparations of cytochrome P-450 obtained from Pseudomonas putida and of cytochrome b(5) obtained from rat livers.

Animals↗