This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
The concrete saccharine exudation of Fraxinus ornus is almost universally official. The Netherlands recognize mannite and not manna. Manna is a mild laxative suitable to give to children. It is administered in milk and is pleasant to the taste. Average dose, 4 drachms. Mannite is a peculiar sugar. Tamarindus, N. F. IV, from Tamarindus Indica, is another saccharine laxative almost universally official but deleted from the U. S. P. IX. It is used in the same dosage as manna and is an ingredient of the old confections. Cassia, from Cassia fistula, has also been deleted from the U. S. P., but is official in several countries. It is another of the saccharine laxatives, but is apt to cause griping. Its average dose is 60 grains. Prunum, from Prunus domestica, was official in the U. S. P. VIII, but is now listed in the National Formulary. It is a laxative when eaten in quantity as a dessert. Prunes contain benzoic acid, which is excreted by the kidneys in the form of hippuric acid; so prunes and cranberries are used to acidify the urine. Ficus, Figs from F. carica, were official in the U. S. P. VIII. They are laxative, partly from the sugar content and partly from the small seeds therein acting mechanically.
This whole class, as well as "Agar," q. v., are laxative largely on account of the bulk of nonabsorbable matter: the sugar content is not the only factor. Bran bread, prepared brans, and many other bulky foods serve much the same purpose. The mineral hydrocarbon oils are also mechanical laxatives. These simple agents should be more largely used instead of so many laxative pills.