=CORTEX ALSTONIÆ.=
_Cortex Alstoniæ scholaris_; _Dita Bark_;[1556] _Alstonia Bark_.
=Botanical Origin=—_Alstonia[1557] scholaris_ R. Brown (_Echites
scholaris_ L.), a handsome forest tree, 50 to 90 feet in height, common
throughout the Indian Peninsula from the sub-Himalayan region to Ceylon
and Burma; found also in the Philippines, Java, Timor and Eastern
Australia, likewise in Tropical Africa. It has oblong obovate leaves,
in whorls of 5 to 7, and slender pendulous pods a foot or more in
length.
=History=—Saptachhada and saptaparna (literally seven-leaf), occurring
in early Sanskrit epic poetry and also in Susruta, are ancient names
of Alstonia (Dr. Rice). Rheede[1558] in 1678 and Rumphius[1559] in
1741 described and figured the tree, and mentioned the use made of its
bark by the native practitioners. Rumphius also explained the trivial
name _scholaris_ as referring to slabs of the close-grained wood which
are used as school-slates, the letters being traced upon them in sand.
The tonic properties of the bark were favourably spoken of by Graham
in his _Catalogue of Bombay Plants_ (1839), and further recommended
by Dr. Alexander Gibson in 1853[1560]. The drug has a place in the
_Pharmacopœia of India_, 1868.
=Description=—The drug, as presented to one of us by the late Dr.
Gibson and by Mr. Broughton of Ootacamund, consists of irregular
fragments of bark, ⅛ to ½ an inch thick, of a spongy texture, easily
breaking with a short, coarse fracture. The external surface is very
uneven and rough, dark grey or brownish, sometimes with blackish spots;
the interior substance and inner surface (liber) is of a bright buff.
A transverse section shows the liber to be finely marked by numerous
small medullary rays. The bark is almost inodorous; its taste is purely
bitter and neither aromatic nor acrid.
[1555] _Annales de Chimie et de Physique_, March, 1869. 309.
[1556] From _Dita_, the name of the tree in the island of Luzon.
[1557] So named in honour of Charles Alston, Professor of Botany and
Materia Medica (1740-1760) in the University of Edinburgh.—The plant is
figured in Bentley and Trimen, _Med. Pl._ part 25 (1877).
[1558] _Hortus Malabaricus_, i. tab. 45.
[1559] _Herb. Amboin._ ii. tab. 82.
[1560] _Pharm. Journ._ xii. (1853) 422.
=Microscopic Structure=—The cortical tissue is covered with a thin
suberous coat; the middle layer of the bark is built up of a thin
walled parenchyme, through which enormous, hard, thick-walled cells
are scattered in great numbers and are visible to the naked eye, as
they form large irregular groups of a bright yellow colour. Towards the
inner part these stone-cells disappear, the tissue being traversed by
undulated medullary rays, loaded with very small starch grains; many of
the other parenchymatous cells of the liber contain crystals of calcium
oxalate. The longitudinal section of the liber exhibits large but not
very numerous laticiferous vessels, containing a brownish mass, the
concrete milk juice in which all parts of the tree abound.
=Chemical Composition=—The first attempts to isolate the active
principles of this bark were made by two apothecaries, Scharlée at
Batavia[1561] (1862) and Gruppe at Manila[1562] (1872).
In 1875 Jobst and Hesse exhausted the powdered bark with petroleum
ether, and then extracted, by boiling alcohol, the salt of an alkaloid,
which they called _Ditamine_. After the evaporation of the alcohol, it
is precipitated by carbonate of sodium and dissolved by ether, from
which it is removed by shaking it with acetic acid. Ditamine as again
isolated from the acetate forms an amorphous and somewhat crystalline,
bitterish powder of decidedly alkaline character; the barks yields
about 0·02 per cent. of it.
From the substances extracted by means of petroleum ether, as above
stated, Jobst and Hesse further isolated (1) _Echicaoutchin_, C₂₅H₄₀O₂,
an amorphous yellowish mass; (2) _Echicerin_, C₃₀H₄₈O₂, forming
acicular crystals, melting at 157° C.; (3) _Echitin_, C₃₂H₅₂O₂,
crystallized scales, melting at 170°; (4) _Echiteïn_, C₄₂H₇₀O₂, which
forms rhombic prisms, melting at 195°; (5) _Echiretin_, C₃₅H₅₆O₂, an
amorphous substance melting at 52° C.
Echicaoutchin may be written thus: (C₅H₈)₅O₂, echicerin (C₅H₈)₆O₂,
echiretin (C₅H₈)₇O₂; these formulæ at once point out how nearly the
three last named substances are allied. They are probably constituents
of the milky juice of the tree.
Lastly, Jobst and Hesse pointed out the existence of another alkaloid
in Dita bark.
Harnack (1877) on the other hand is of the opinion that it contains
only one alkaloid, which he terms _Ditaïne_. He used the alcoholic
extract of the bark which he treated with ether to which he added a
little ammonia. By this process ditamine of Jobst and Hesse would
have been removed, but Harnack suggests that only a little ditaïne is
dissolved by ether. He then mixed the extract with potash and exhausted
it with alcohol, which afforded crystals of ditaïne, answering to the
formula C₂₂H₃₀N₂O₄; its physiological action is nearly the same as
that of curare. Ditaïne is but sparingly soluble in ether or petroleum
ether, but dissolves readily in water, alcohol, or chloroform; it has a
decidedly alkaline reaction. It would appear that it is a glucoside.
[1561] Geneesk, _Tijdschr. Nederl. Indië_, x. (1863) 209; also _Archiv
der Pharmacie_, 212 (1878) 439.
[1562] _Jahresbericht_ of Wiggers and Husemann, 1873. 51.
Dita bark is stated[1563] to yield 5 per cent. of “ditaïne”; but this
probably refers not to the pure alkaloid.
=Uses=—The bark has been recommended as a tonic and antiperiodic, being
extravagantly praised as a substitute for quinine.