Source, Etc

The official alstonia bark may be obtained either from Alstonia scholaris, Robert Brown (N.O. Apocynaceoe), a tree indigenous to India and the Philippine Islands or from A. constricta, P. Mueller, a native of Australia; the latter bark is also known as Australian fever bark. The former is the variety usually found in commerce.

Description

Alstonia scholaris. This bark, also known as dita bark, occurs in single quills or in irregular curved pieces of varying size and appearance. That from older stems or branches is commonly in small, curved or channelled pieces, or quills, and is of a light, yellowish brown colour, rough, irregularly fissured, and spongy externally; internally it is darker. Such pieces break with a short fracture, the section exhibiting a narrow inner portion (cortex and secondary bast) traversed by numerous, fine medullary rays and a spongy outer portion (cork) of varying thickness. The bark from young branches bears scattered, pale lenticels and is very fibrous. Both kinds contain numerous, pitted, sclerenchymatous cells, laticiferous vessels, and prismatic crystals of calcium oxalate, but the young bark contains abundant pericyclic fibres which are seldom visible in old bark. Taste bitter, no odour.

Alstonia constricta. The bark is in quills or channelled pieces, often of considerable size. Outer surface brown or yellowish brown in colour and deeply fissured both longitudinally and transversely; inner surface cinnamon brown in colour and deeply striated. The transverse section exhibits an abundant, dark brown cork, within which is a yellowish brown secondary bast. The latter exhibits under the microscope abundant bast fibres in tangentially arranged groups. The taste is very bitter. The aqueous infusion is yellowish and shows a well marked blue fluorescence.

Constituents

Alstonia scholaris. The chief constituents are the alkaloids ditamine (bitter, crystalline powder), echitenine (amorphous, bitter powder) and echitamine or ditaine. The bark also contains echicerin (crystalline, non-nitrogenous), echicaoutchin (resembles caoutchouc), echitin and echitein (both crystalline), and echiretin (amorphous); all these constituents appear to be devoid of therapeutic value.

Alstonia constricta. This bark contains the alkaloids alstonine (chlorogenine) and porphyrine; also alstonidine and porphyrosine concerning which little definite is known. Porphyrine in acid solution exhibits a blue fluorescence.

Uses

The bark is used in India for malaria but is inferior in value to cinchona bark; it has also been used as a tonic, anthelmintic, and in chronic diarrhoea.