_Colocynth_, _Coloquintida_, _Bitter Apple_; F. _Coloquinte_; G.
_Coloquinthe_.
=Botanical Origin=—_Citrullus Colocynthis_ Schrader (_Cucumis
Colocynthis_ L.)—The colocynth gourd is a slender scabrous plant with a
perennial root, native of warm and dry regions in the Old World, over
which it has an extensive area.
Commencing eastward, it occurs in abundance in the arid districts
of the Punjab and Sind, in sandy places on the Coromandel coast, in
Ceylon, Persia as far north as the Caspian, in Arabia (Aden), Syria,
and in some of the Greek islands. It is found in immense quantities
in Upper Egypt and Nubia, spreading itself over sand hillocks of the
desert after each rainy season. It further extends throughout North
Africa to Morocco and Senegambia, in the Cape de Verd Islands, and on
maritime sands in the south-east of Spain and Portugal. Finally, it is
said to have been collected in Japan.
=History=—Colocynth was familiar to the Greek and Roman, as well as
to the Arabian physicians; it also occurs in Susruta (“Indravārunī”);
and if we may judge by the mention of it in an Anglo-Saxon herbal of
the 11th century,[1130] was not then unknown in Britain. The drug was
collected in Spain at an early period, as is evident from an Arabic
calendar of A.D. 961.[1131]
The plant has been long cultivated in Cyprus, and its fruit is
mentioned in the 14th century as one of the more important products of
the island.[1132] Tragus (1552) figured the plant, and stated that the
fruit is imported from Alexandria.
=Description=—The colocynth plant bears a gourd of the size and shape
of an orange, having a smooth, marbled-green surface. It is sometimes
imported simply dried, in which case it is of a brown colour; but
far more usually it is found in the market peeled with a knife and
dried. It then forms light, pithy, nearly white balls, which consist
of the dried internal pulp of the fruit with the seeds imbedded in
it. This pulp is nearly inodorous, but has an intensely bitter taste,
perceptible by reason of its dust when the drug is slightly handled.
The balls are generally more or less broken; when dried too slowly they
have a light brown colour.
[1129] Clutterbuck says ⅛ of a grain purges violently.
[1130] Cockayne, _Leechdoms_, etc., i. (1865) 325.
[1131] _Le Calendrier de Cordoue_, publié par R. Dozy, Leyde, 1873. 92.
[1132] De Mas Latrie, _Hist. de l’ile de Chypre_, iii. (1852-61) 498.
The seeds are disposed in vertical rows on 3 thick parietal placentæ,
which project to the centre of the fruit, then divide and turn back,
forming two branches directed towards one another. Owing to this
structure, the fruit easily breaks up vertically into 3 wedges in each
of which are lodged 2 rows of dark brown seeds. The seeds, of which a
fruit contains from 200 to 300, are of flattened ovoid form, ³/₁₀ of
an inch long by ²/₁₀ broad, not bordered. The testa which is hard and
thick, having its surface minutely granulated, is marked on each side
of its more pointed end by two furrows directed towards the hilum. The
seed, as in other _Cucurbitaceæ_, is exalbuminous, and has thick oily
cotyledons, enclosing an embryo with short straight radicle directed
towards the hilum.
Colocynth fruits are mostly supplied by wholesale druggists, broken
up and having the seeds removed, the drug in such case being called
_Colocynth Pulp_ or _Pith_.
=Microscopic Structure=—The pulp is made up of large thin-walled
parenchymatous cells, their outer layer consisting of rows of smaller
cells more densely packed. The tissue is irregularly traversed by
fibro-vascular bundles, and also exhibits numerous large intercellular
spaces. The cells contain but an insignificant amount of minute
granules, to which neither iodine nor a persalt of iron imparts any
coloration. The tissue is not much swollen by water, although one part
of the pulp easily retains from 10 to 12 parts of water like a sponge.
=Chemical Composition=—The bitter principle has been isolated in 1847
by Hübschmann.[1133] He observed that alcohol removes from the fruit a
large amount of _resin_. By submitting this solution to distillation,
the bitter principle remains partly in the aqueous liquid, partly
in the resin, from which the “_Colocynthin_” is to be extracted by
boiling water. The whole solution was then concentrated and mixed
with carbonate of potassium, when a thickish viscid liquid separated.
Hübschmann dried it and redissolved it in a mixture of 1 part of strong
alcohol and 8 parts of ether. After treatment with charcoal, the
solvents were distilled and the remaining bitter principle removed by
means of water. This on evaporating afforded 2 per cent. of the pulp of
a yellow extremely bitter powder, readily soluble in water or alcohol,
not in pure ether. Colocynthin is precipitated from its aqueous
solution by carbonate of potassium. Colocynthin was further extracted
by Lebourdais (1848) by evaporating the aqueous infusion of the fruit
with charcoal, and exhausting the dried powder with boiling alcohol.
[1133] _Schweizerische Zeitschrift für Pharmacie_, 1858. 216.
Again, another method was followed by Walz (1858). He treated alcoholic
extract of colocynth with water, and mixed the solution firstly with
neutral acetate of lead, and subsequently with basic acetate of
lead. From the filtered liquid the lead was separated by means of
sulphuretted hydrogen, and then tannic acid added to it. The latter
caused the colocynthin to be precipitated; the precipitate washed and
dried was decomposed by oxide of lead, and finally the colocynthin was
dissolved out by ether.
Walz thus obtained about ¼ per cent. of a yellowish mass or tufts,
which he considered as possessing crystalline structure and to which he
gave the name _Colocynthin_. He assigns to it the formula C₅₆H₈₄O₂₃,
which in our opinion requires further investigation. Colocynthin is
a violent purgative; it is decomposed according to Walz by boiling
dilute hydrochloric acid, and then yields _Colocyntheïn_, C₄₄H₆₄O₁₃,
and grape sugar. The same chemist termed _Colocynthitin_ that part of
the alcoholic extract of colocynth which is soluble in ether but not in
water. Purified with boiling alcohol, colocynthitin forms a tasteless
crystalline powder.
The pulp perfectly freed from seeds and dried at 100° C., afforded us
11 per cent. of ash; the seeds alone yield only 2·7 per cent. They
have, even when crushed, but a faint bitter taste, and contain 17 per
cent. of fat oil.
The fresh leaves of the plant if rubbed emit a very unpleasant smell.
=Commerce=—The drug is imported from Mogador, Spain and Syria.
=Uses=—In the form of an extract made with weak alcohol, and combined
with aloes and scammony, colocynth is much employed as a purgative. The
seeds, roasted or boiled, are the miserable food of some of the poorest
tribes of the Sahara.[1134]
The people of the Berber upon the Nile make a curious application
for the tar they obtain from the fruit. The latter is heated in an
earthen vessel with a hole in it; the tar drips through to another
vessel and is fit for smearing leather water-bags. The bad smell of
the tar (and of the leaves) prevents the camels from cutting open the
water-bags.[1135]
=Substitutes=—_Cucumis trigonus_ Roxb. (_C. Pseudo-colocynthis_ Royle),
a plant of the plains of Northern India, with spherical or elongated,
sometimes obscurely trigonous, bitter fruits, prostate _rooting_ stems,
and deeply divided leaves, resembles the colocynth gourd and has been
mistaken for it. Another species named by Royle _C. Hardwickii_, and
known to the natives of India as _Hill Colocynth_, has oval oblong
bitter fruits, but leaves entirely unlike those of the _Citrullus
Colocynthis_.