The Active Constituents Of The Vegetable Purgatives Containing Anthracene Derivatives: Part I. Glycosides and Aglycones

Abstract

A review of the published theories which seek to account for the activity of purgative drugs containing anthracene derivatives is given. The relative activity of anthracene derivatives occurring as (a) glycosides, (b) anthranols and (c) anthraquinones, in certain crude drugs has been determined by biological means. A similar investigation of isolated glycosides, anthranols and anthraquinones has been carried out. The results show that the anthracene derivatives are highly active as anthranol glycosides; less active as free anthranols and much less active as free anthraquinones. The more complex aglycone (dianthranol) of sennoside A is more active than the simple anthranol of aloe emodin. The theory is advanced that the sugar moiety of the glycoside not only acts as a “transporter” of the active aglycone, enabling it to reach the large intestine, but is also a “protector” which prevents oxidation of the aglycone to the relatively (orally) inactive anthraquinone. The experiments also show that a determination of “total anthraquinones” irrespective of their form of occurrence will be no guide to biological activity. Further work on the glycoside fraction of these crude drugs is being carried out. I would like especially to thank Mr. T. C. Lou for performing all the bio‐assays included in this paper, for preparing the pure anthracene compounds and for much valuable assistance and many useful suggestions during the course of the work. I am also grateful to the Pharmacology Department of this School for facilities for carrying out the bio‐assays; and to the Department of Physical Chemistry for the loan of certain spectrophotometric equipment necessary for the colorimetric assays. Acknowledgments are made to Sandoz Products Ltd.*** for the gift of sennosides A and B, and to Mr. A. H. Fenton for the preliminary biological work. 1949 Royal Pharmaceutical Society of Great Britain