The compounds in Aloë leaf exudates: a review

Die Dianthrone der pharmazeutisch interessierenden Hydroxyanthrachinone

Durch reduzierende Acetylierung des Hypericins wurde eine blaue, kristallisierte Verbindung dargestellt. Es wird gezeigt, das sie 4.5.7.10.4′.5′.7′-Heptaacetoxy-2.2′-dimethyl-meso-naphthodianthren ist und damit der endgultige Beweis fur die Konstitution des Hypericins erbracht. Eine Hypothese uber die Entstehung des Hypericins in der pflanze wird diskutiert.

Die Konstitution des Hypericins

The details of the total synthesis of viridicatumtoxin B (1) are described. Initial synthetic strategies toward this intriguing tetracycline antibiotic resulted in the development of key alkylation and Lewis acid-mediated spirocyclization reactions to form the hindered EF spirojunction, as well as Michael–Dieckmann reactions to set the A and C rings. The use of an aromatic A-ring substrate, however, was found to be unsuitable for the introduction of the requisite hydroxyl groups at carbons 4a and 12a. Applying these previous tactics, we developed stepwise approaches to oxidize carbons 12a and 4a based on enol- and enolate-based oxidations, respectively, the latter of which was accomplished after systematic investigations that revealed critical reactivity patterns. The herein described synthetic strategy resulted in the total synthesis of viridicatumtoxin B (1), which, in turn, formed the basis for the revision of its originally assigned structure. The developed chemistry facilitated the synthesis of a ser...

Total Synthesis of Viridicatumtoxin B and Analogues Thereof: Strategy Evolution, Structural Revision, and Biological Evaluation

The purgative activities of 18 different dihydroxyanthracene derivatives, including free anthraquinones and anthrones, were investigated by determining their influence on the water, sodium and potassium absorption in the gastrointestinal tract by direct injection of the solutions in Tyrode to the rat colon in situ. The extent of the solubility of the compounds has also been assessed. The 1,8-dihydroxyanthracene structure seemed to be the best for hydragogue effect. Rhein-anthraquinone and -anthrone were the most active compounds tested.

The influence of dihydroxyanthracene derivatives on water and electrolyte movement in rat colon.

Die Konstitution der Sennoside A und B als Derivate des Dihydro-dianthrons wird bewiesen durch ihre reduktive Spaltung zu 9-Rheinanthron-Derivaten und durch Darstellung von 9,9′-Diacetyl-verbindungen mit Dianthranol-Struktur.

A. Stoll

Papers

Die Konstitution der Sennoside. 6. Mitteilung über Anthraglykoside