Source, Etc

The thornapple, Datura Stramonium, Linne (N.O. Solanaceoe), is a large bushy annual attaining about 1 metre in height, a native probably of the shores of the Caspian Sea, but found commonly on waste ground throughout the temperate and warmer regions, abundant in South Africa, and met with occasionally in England, escaped from cultivation. It is cultivated in this country, but our supply of the drug is derived largely from Germany, France, and Hungary. The introduction of stramonium into medicine is due chiefly to the exertions of Storck in the latter half of the eighteenth century. The leaves only are official, but usually the young shoots are collected when the plant is in flower and dried.

Description

The stem of the thornapple is stout and erect, branching repeatedly, and producing in the forks of the branches a leaf and a single flower with a tubular calyx and large, white, funnel-shaped corolla. This flower is succeeded by an erect, spiny capsule about the size of a walnut. In addition to mature and young leaves the drug therefore frequently contains the remains of the flower with a tubular calyx and yellowish corolla, or of the young, shrivelled, bristly fruit.

The dried leaves are usually much shrivelled and wrinkled; they are of a dark greyish green colour, especially on the upper surface, ovate in outline, petiolate, and often unequal at the base. They attain 20 cm. or more in length, and are characterised by the very coarse pointed teeth which impart to the margin a sinuate-dentate outline; the apex of the leaves is shortly acuminate. On the under surface the midrib is distinct though not very prominent; the lateral veins leave it at an angle of about 45° and divide when near the margin, one branch passing into the pointed lobe of the leaf, whilst the other anastomoses with other, tertiary, veins. When quite young the leaves are covered with stout curved hairs, but as they reach maturity these fall off, and full-grown leaves are glabrous or nearly so. The odour of the drug, though not strong, is disagreeable and characteristic; the taste is unpleasantly bitter.

Microscopical Characters

The distinctive characters of stramonium leaves are the abundant cluster crystals of calcium oxalate in the mesophyll; the hairs though not numerous, are also characteristic, being either simple, uniserial, three- to five-celled, and warty, or small, shortly stalked, and glandular. The leaves possess in addition typical Solanaceous stomata and bicollateral bundles devoid of bast-fibres.

Fig. 32.   Thornapple leaf. Under surface, showing the venation. Natural size.

Fig. 32. - Thornapple leaf. Under surface, showing the venation. Natural size.

The student should carefully observe

(a) The curled and twisted appearance of the dried leaves,

(b) The angle made by the lateral veins with the midrib,

(c) The occasional presence of the remains of the flower and fruit,

(d) The characteristic odour, and,

(e) After soaking in water, the sinuate-dentate outline (unless the leaves are too much broken); and should compare them with

(i) Belladonna leaves (see p. 43), (ii) Henbane leaves (see p. 49), (iii) Foxglove leaves (see p. 53).

Constituents

Stramonium leaves contain the same alkaloids as belladonna leaves, but in somewhat smaller proportion, the average of commercial samples being about 0.22 per cent.; the percentage may, however, rise to 0.4 or exceptionally to 0.7 per cent.; South African leaves 0.54 per cent., Egyptian 0.35 per cent (hyoscyamine only). Daturine was the name given to the mixture of alkaloids originally extracted from the drug.

The alkaloids in the leaf are localised chiefly in the epidermis, particularly the upper, and in the bast parenchyma of the veins, the midrib containing more than the petiole, and both being much richer than the leaf. Hence the practice sometimes followed of rubbing the leaves through a coarse sieve (laminating), and rejecting the midribs and larger veins should be discontinued, especially as thereby the difficulty of identifying the leaves is increased. The main stem contains but little alkaloid, and therefore should not be present in the drug.

Assay

The drug may be assayed by the process official for belladonna leaves.

Adulterations

Xanthium strumarium (N.O. Compositœ); short, conical hairs containing cystoliths, uniserial, simple hairs and globular, multicellular, glandular hairs; no cluster crystals of calcium oxalate.

Xanthium macrocarpum, de Candolle; said to possess three forms of hairs, two protective and one glandular, one of the former being short and lignified; cluster-crystals smaller and less numerous; transverse section of the midrib shows six bundles (D. Stramonium has only one).

Carthamus helenioides, Desfontaines; epidermal cells large, walls straight, cuticle striated; large, pericellular protective hairs, small glandular hairs arising from the whole surface of an epidermal cell (in D. Stramonium from a small spot); no cluster-crystals; well-developed secreting ducts.

Chenopodium hybridumt Linne; cluster-crystals abundant; epidermal cells small, walls nearly straight; occasional hairs with slender pedicel and large, bladdery, water-storing terminal cell.

Solanum nigrum, Linne; hairs resemble stramonium; contains no cluster-crystals.

Uses

Stramonium leaves resemble belladonna in their action; they are, however, almost exclusively used in the treatment of spasmodic affections of the respiratory organs.