Related entries: Dulcamara (U. S. P.)—Dulcamara
The root and fruit of Solanum Carolinense, Linné.
COMMON NAMES: Horse-nettle, Bull-nettle, Sand-brier, Threadsoft, Threadsaf.
Botanical Source.—Horse-nettle is an herbaceous perennial plant, from 8 to 18 inches high. The stem is simple and erect, though sometimes prostrate and branching from the root. The more or less contorted root is from ⅛ to ¼ inch in diameter, having a thick bark surrounding a slender woody center; it descends deeply and vertically into the soil. The leaves are alternate, oblong, ovate; obtusely lobed, wavy, with yellowish prickles on midrib and larger veins of both surfaces, and extending along the petiole and main stem, where they become quite stout. The surfaces of stems and leaves are stellate (4, 6, or 8-rayed) pubescent. The flowers are borne in simple cymes or racemes, becoming lateral in fruit. Flowers regular, calyx 5-parted, sepals pointed, corolla rotate, with 5 ovate lobes and pale-blue, violet, or more rarely white. Stamens 5, yellow, inserted on the corolla; anthers 4-celled, 4 times as long as the filaments, and opening by pores at the tip. They are connivent and form a cone around the pistil. The style and stigma are single. The fruit, when ripe, is an orange- or lemon-colored berry from ½ to ⅗ inch in diameter; 2-celled, the seeds being attached to the central placenta. The seeds are pale-yellow, smooth, shining, oval, and flattened. The dried fruit has a shrunken or reticulated appearance. (Also see microscopy and illustration of Solanum Carolinense, by C. J. Johnson, in Amer. Jour. Pharm., 1897, pp. 76-84, and by M. C. Thrush, ibid., pp. 84-89.)
History.—Horse-nettle is a common and abundant wild plant flourishing in waste places and around cultivated fields, frequently in patches in almost all parts of our country. It grows from Connecticut to Iowa, and southward to the Gulf of Mexico. It frequently grows so abundantly as to be a nuisance, preferring sandy or gravelly slopes, railroad grades, etc., with a south sunny exposure. The root and berries are employed medicinally. Specific solanum carolinense is prepared from the root. Attention was called to this plant by Porcher (Report on Indigenous Medical Plants of South Carolina) in the middle of the present century, who quotes from a French work (Mérat and De Lens Dictionnaire Univ. de Matière Médicale, Paris, Vol. VI, 1837) that M. Louis Valentin used the berries in idiopathic or non-traumatic tetanus (see also A. Clapp, M. D., Report on Medical Botany, 1850--51; and Robert Hogg, Natural History of the Vegetable Kingdom, 1858). Porcher also refers to an article (Journal Gén. de Méd., Vol. XL, p. 13), which gives "A notice of the different methods of treating Tetanus in America, with observations on the good effects of the S. Carolinense." According to Porcher, it possessed "some reputation among the negroes of this state (South Carolina) as an aphrodisiac." Its revival as a medicine was due to reports by Dr. J. L. Napier, of Blenheim, S. C. (Medical World, 1889; and Amer. Therapist, 1892).
Chemical Composition.—Complete chemical analyses of the root-bark, leaves and berries of Solanum Carolinense were made by G. A. Krauss (Amer. Jour. Pharm., 1890, p. 601, and 1891, pp. 65 and 216); of the berries, also by Harry Kahn (ibid., 1891, p. 126). From the root-bark Krauss obtained by consecutive extraction with petroleum-ether and ether, an alkaloid crystallizing in hard, shining prisms, soluble in ether, benzol, and chloroform, and being non-glucosidal. Alcohol then abstracted a glucosidal alkaloid which showed the reactions for solanine. The ether-soluble alkaloid, the author believes to be probably solanidine (compare Dulcamara). The leaves and the berries contain the same substances. Prof. J. U. Lloyd (Amer. Jour. Pharm., 1894, p. 161) independently obtained from the root of this plant an ether-soluble, well-crystallizable alkaloid (see illustration, above), which he provisionally named solnine. It is practically insoluble in water and diluted ammonia water, soluble in diluted acids and in cold chloroform; from boiling alcohol it crystallizes in needles resembling hydrastine. Its melting point is 131° C. (267.8° F.), thus differing markedly from solanine, which melts at 235° C. (455° F.), also differing from solanidine, the melting point of which, according to Watt's Dictionary, is 191° C. (375.8° F.). The root-bark contains about 0.4 per cent, the berries about 1.3 per cent, of total alkaloids, the presence of which explains the toxic action of the drug. (For further constituents of volatile oil, starch, solanic acid, etc., see the papers quoted.)
Action, Medical Uses, and Dosage.—This agent is reputed antispasmodic, and has been recommended chiefly for convulsive disorders. It was early used by Valentin in non-traumatic tetanus (see Medical History). While success with it has been recorded in chorea, puerperal eclampsia, infantile, and hysterical convulsions, its chief use has been in epilepsy, and particularly that form in which the paroxysms are severest at or brought on at the menstrual periods. The drug needs further investigation. The dose of the fluid extract is from 10 to 60 drops; of specific solanum carolinense, 10 to 30 drops.