_Semen Pharbitidis_; _Kaladana_.
=Botanical Origin=—_Ipomœa Nil_[1652] Roth (_Pharbitis Nil_ Choisy,
_Convolvulus Nil_ L.), a twining annual plant, with a large blue
corolla, much resembling the Major Convolvulus (_Pharbitis hispida_
Choisy) of English gardens, but having three-lobed leaves.[1653] It
is found throughout the tropical regions of both hemispheres, and is
common in India, ascending the mountains to a height of 5000 feet.
=History=—The seeds of this plant were employed in medicine by the
Arabian physicians under the name _Habbun-nil_; and they have probably
been long in use among the natives of Hindustan. In recent times
they have been recommended by O’Shaughnessy, Kirkpatrick, Bidie,
Waring[1654] and many other European practitioners in India as a safe
and efficient cathartic.
=Description=—The shape of the seeds is that which would result if a
nearly spherical body were divided perpendicularly around its axis into
6 or 8 almost equal segments, only that the back is less regularly
vaulted. The seeds are ¼ of an inch high and nearly as much broad; 100
of them weigh on an average about 6 grammes. There is a smaller variety
imported from Calcutta, of which 100 seeds weigh but little over 3
grammes; in every other respect the two sorts are identical. Both
are of a dull black, excepting at the umbilicus, which is brown and
somewhat hairy. The adjacent parts of the thin shell (testa) crack in
various directions, if the seed is kept for a short time in cold water.
If it is removed from the upper part of the vaulted back, the radicle
becomes visible, surrounded by the undulated folds of the cotyledons,
which join perpendicularly, but cannot be easily unfolded by reason
of the thin seminal integument. Cut transversely, the cotyledons show
the same curled structure. Throughout their tissue, small bright
glands in considerable number are observable, even without a lens. The
kernel, which is devoid of albumen, has at first a nutty taste, with
subsequently a disagreeable persistent acridity. When bruised in a
mortar, the seeds evolve a heavy earthy smell.
=Microscopic Structure=—The seed is covered with a dark blackish
cuticle, formed of a densely packed tissue, the cells of which show
zigzag outlines. The dark brown epidermis is composed of very close
cylindrical cells, about 70 mkm. in length and 5 to 7 mkm. in diameter;
they require to be treated with chromic acid in order that their
structure may be distinctly seen.
The tissue of the kernels is made up of thick-walled cells. Between
this tissue and the shell there is a colourless layer, about 70 mkm.
thick, of thin-walled corky parenchyme. The cotyledons contain in
their narrow tissue numerous granules of albuminous matter, mucilage,
a little tannic acid, crystals of oxalate of calcium, and a few starch
granules. The glands or hollows, before alluded to as occurring
throughout the tissue of the cotyledons, are about 70 mkm. in diameter,
and contain an oily liquid.
[1652] In Hindustani _Nil_ signifies _blue_, and _Kaladana_, black seed.
[1653] Fig. in Bentley and Trimen, _Med. Plants_, part 22 (1877).
[1654] _Pharm. Journ._ vii. (1866) 496.
=Chemical Composition=—By exhausting the seeds dried at 100° C. with
boiling ether, we obtained a thick light brownish oil having an acrid
taste and concreting below 18° C. The powdered seeds yielded of this
oil 14·4 per cent. Water removes from the seeds a considerable amount
of mucilage, some albuminous matter and a little tannic acid. The
first is soluble to some extent in dilute spirit of wine, and may be
precipitated therefrom by an alcoholic solution of acetate of lead.
The active principle of kaladana is a _resin_, soluble in alcohol, but
neither in benzol nor in ether. From the residue of the seeds after
exhaustion by ether, treatment with absolute alcohol removed a pale
yellowish resin in quantity equivalent to 8·2 per cent. of the seed.
Kaladana resin, which has been introduced into medical practice in
India under the name of _Pharbitisin_,[1655] has a nauseous acrid taste
and an unpleasant odour, especially when heated. It melts about 160° C.
The following liquids dissolve it more or less freely, namely, spirit
of wine, absolute alcohol, acetic acid, glacial acetic acid, acetone,
acetic ether, methylic and amylic alcohol, and alkaline solutions.
It is on the other hand insoluble in ether, benzol, chloroform, and
sulphide of carbon. With concentrated sulphuric acid, it forms a
brownish yellow solution, quickly assuming a violet hue. This reaction
however requires a very small quantity of the powdered resin. If a
solution of the resin in ammonia, after having been kept a short time,
is acidulated, no precipitate is formed; but the solution is now
capable of separating protoxide of copper from an alkaline solution of
the tartrate, which originally it did not alter. Heated with nitric
acid, the resin affords _sebacic acid_ (see p. 446).
From these reactions of kaladana resin, we are entitled to infer that
it agrees with the resin of jalap or _Convolvulin_. To prepare it in
quantity, it would probably be best to treat the seeds with common
acetic acid, and to precipitate it by neutralizing the solution. We
have ascertained that the resin is not decomposed when digested with
glacial acetic acid at 100° C., even for a week.
We have had the opportunity of examining a sample of kaladana resin
manufactured by Messrs. Rogers and Co., chemists of Bombay and Poona,
which we found to agree with that prepared by ourselves. It is a light
yellowish friable mass, resembling purified jalap resin, and like
it, capable of being perfectly decolorized by treatment with animal
charcoal.
=Uses=—Kaladana seeds have cathartic powers like jalap. Besides the
resin, an extract, tincture and compound powder have been introduced
into the _Pharmacopœia of India_. In many parts of India the natives
take the roasted seeds as a purgative.
[1655] _Pharmacopœia of India_, 1868, 156.