_Belladonna Leaves_; F. _Feuilles de Belladone_; G. _Tollkraut_.
=Botanical Origin=—_Atropa Belladonna_ L. (p. 455).
=History=—Belladonna Leaves and the extract prepared from them
were introduced into the London Pharmacopœia of 1809. For further
particulars regarding the history of belladonna, see the preceding
article.
=Description=—Belladonna or Deadly Nightshade produces thick, smooth
herbaceous stems, which attain a height of 4 to 5 feet. They are simple
in their lower parts, then usually 3-forked, and afterwards 2-forked,
producing in their upper branches an abundance of bright green leaves,
arranged in unequal pairs, from the bases of which spring the solitary,
pendulous, purplish, bell-shaped flowers, and large shining black
berries.
The leaves are 3 to 6 inches long, stalked, broadly ovate, acuminate,
attenuated at the base, soft and juicy; those of barren roots are
alternate and solitary. The young shoots are clothed with a soft, short
pubescence, which on the calyx is somewhat more persistent, assuming
the character of viscid, glandular hairs. If bruised, the leaves emit
a somewhat offensive, herbaceous odour which is destroyed by drying.
When dried, they are thin and friable, of a brownish-green on the upper
surface and greyish beneath, with a disagreeable, faintly bitter taste.
Of fresh leaves 100 lb. yield 16 lb. of dried (Squire).
=Chemical Composition=—The important constituent of belladonna leaves
is _Atropine_. Lefort (1872)[1679] estimated its amount by exhausting
the leaves previously dried at 100° C. by means of dilute alcohol,
concentrating the tincture, and throwing down the alkaloid with a
solution of iodohydrargyrate of potassium. The precipitate thus
obtained was calculated to contain 33·25 per cent. of atropine. Lefort
examined leaves from plants both cultivated and growing wild in the
environs of Paris, and gathered either before or after flowering. He
found cultivation not to affect the percentage of alkaloid,—that the
leaves of the young plant were rather less rich than those taken at the
period of full inflorescence,—and that the latter (dried) yielded 0·44
to 0·48 per cent. of atropine.
[1678] Gmelin, _Chemistry_, xvii. (1866) 1.
[1679] _Journ. de Pharm._ xv. (1872) 269. 341.
Larger percentages are recorded by Dragendorff;[1680] as much as 0·95
per cent. of atropine as obtained from the dried unripe fruits, 0·83
from the dried leaves, 0·21 from the root. The estimation was performed
in nearly the same way as that followed by Lefort.
Belladonna herb yields _Asparagin_, which according to Biltz (1839)
crystallizes out of the extract after long keeping. The crystals found
in the extract by Attfield (1862) were however chloride and nitrate
of potassium. The same chemist obtained by dialysis of the juice of
belladonna, nitrate of potassium, and square prisms of a salt of
magnesium containing some organic acid; the juice likewise affords
ammonia.[1681] The dried leaves yielded us 14·5 per cent. of ash
consisting mainly of calcareous and alkaline carbonates.
=Uses=—The fresh leaves are used for making _Extractum Belladonnæ_, and
the dried for preparing a tincture. They should be gathered while the
plant is well in flower.