Fortschritte der Chemie Organischer Naturstoffe/Progress in the Chemistry of Organic Natural Products/Progres dans la Chimie des Substances Organiques Naturel es

Substances belonging to this group of organic compounds are wi,lely distributed in Nature, being found in plants, both higher and lower fungi and, upto the present time, in one animal source, sheep wool-fat. For a long time no real differentiation was possible between the tetra- and penta cyclic triterpenes and the sterols. Then the two latter became disting uishable by their selenium. ·dehydrogenation products, i. e. , picene and naphthalene derivatives from the pentacyclic triterpenes and DIELS' hydrocarbon from the sterols. It is now apparent that those compounds yielding predominantly I: 2: 8-trimethylphenanthrene on dehydro genation represent yet another class, and this property is regarded as typical of the tetracyclic triterpenes. The group contains both C and C 30 3l compounds and, although the latter fall outside RUZICKA'S strict definition of triterpenes (I42), it seems desirable to permit this deviation. Members with thirty-two carbon atoms may well be discovered in due course. In a most· valuable account of the triterpenes written in I949, JEGER. (II3) was able to summarize all that was known about the tetra cyclic group in a very small compass. Most of the work discussed in the present article has been published during the last five years and in that time the structures of some twenty compounds have been elucidated. Of outstanding importance is the revelation of close structural relation ships tQ the steroids, and the presence of C and C side-chains, skeletally 8 9 identical with those of cholesterol and ergosterol.

Contenu
/ Contents / Table des matières.- Sesquiterpenes and Diterpenes.- II. Diterpenes.- III. The Biogenesis of Sesqui- and Diterpenes.- References.- Tetracyclic Triterpenes.- I. Introduction.- II. Lanostane Type Group.- III. Euphane Type Group.- IV. Compounds of Unknown Structure.- References.- Neuere Vorstellungen auf dem Gebiete der Biosynthese der Steroide und verwandter Naturstoffe.- I. Einleitung.- II. Steroidbiogenese mit markierten Verbindungen.- III. Unsere Kenntnisse der biologischen Beziehungen der Steroide untereinander.- IV. Die Hypothesen der Steroidbiogenese.- V. Schlußbetrachtung.- Some Biochemical Aspects of Fungal Carotenoids.- I. Introduction.- II. Occurrence of Carotenoids in Fungi.- III. Carotenoid Formation in Fungi.- IV. Physiological Role of Fungal Carotenoids.- V. Conclusion.- References.- The Pyrrolizidine Alkaloids.- I. Introduction: Origin, Occurrence and Nature of the Pyrrolizidine Alkaloids.- II. The Basic Hydrolysis Products.- III. The Acid Hydrolysis Products.- IV. The Structures of the Alkaloids.- V. Pharmacology (with M. E. Von Klemperer).- References.- Paper Chromatography in the Study of the Structure of Peptides and Proteins.- I. Principles of Paper Chromatography.- II. Paper Chromatographic Techniques.- III. The Determination of the Amino Acid Composition of Peptides and Proteins.- IV. Identification of Terminal Sequences in Peptides and Proteins.- V. The Determination of Amino Acid Sequences in Long Chain Polypeptides and Proteins.- VI. Concluding Remarks.- References.- Acides aminés iodés et iodoprotéines.- I. Introduction.- II. Les acides aminés iodés.- III. Iodoprotéines.- Bibliographie.- Chemistry and Biochemistry of Snake Venoms.- I. Introduction.- II. Snakes and Venoms.- III. The Action of Venoms.- IV. Enzymes from SnakeVenoms.- V. Separation, Purification, and Crystallization of Biologically Active Venom Constituents.- VI. Electrophoresis of Snake Venoms.- References.- Gene Structure and Gene Action.- The Gene as a Biological Unit.- The Chemistry of the Genetic Material.- Transforming Principles.- The Genetics of Viruses.- The Structure of DNA.- Gene Specificity.- Gene Reproduction.- Gene Mutation.- Gene Function.- Genetics of Hemoglobin Structure.- Genes and Enzymes.- Genes and Aromatic Amino Acids.- Summarizing Discussion.- References.- Namenverzeichnis. Index of Names. Index des Auteurs.- Sachverzeichnis. Index of Subjects. Index des Matières.