SENNA (Arab. saná), a popular purgative, consisting of the leaves of two species of Cassia, viz., C. acutifolia, Del., and C. angustifolia, Vahl. C. acutifolia is a native of many districts of Nubia, e.g., Dongola, Berber, Kordofan, and Senaar, but is grown also in Timbuctoo and Sokoto. The leaflets are collected twice a year by the natives, the principal crop being gathered in September after the rainy season and a smaller quantity in April. The leaves are dried in the simplest manner by cutting down the shrubs and exposing them on the rocks to the burning sun until quite dry. The leaflets then readily fall off and are packed in large bags made of palm leaves, and holding about a quintal each. These packages are conveyed by camels to Assouan and Darao and thence to Cairo and Alexandria, or by ship by way of Massowah and Suakim. The leaflets form the Alexandrian senna of commerce. Formerly this variety of senna was much adulterated with the leaves of Solenostemma Argei, Hayne, which, however, are readily distinguishable by their minutely wrinkled surface. Of late years Alexandrian senna has been shipped of much better quality. Occasionally a few leaves of C. obovata, Coll., may be found mixed with it. C. angustifolia affords the Bombay, East Indian, Arabian, or Mecca senna of commerce. This plant grows wild in the neighbourhood of Yemen and Hadramaut in the south of Arabia, in Somali Land, and in Sind and the Punjab in India. The leaves are chiefly shipped from Mocha, Aden, Jeddah, and other Red Sea ports to Bombay and thence to Europe, the average imports into Bombay amounting to about 250 tons annually, of which one-half is re-exported. Bombay senna is very inferior in appearance to the Alexandrian, as it frequently contains many brown and decayed leaflets and is ...mixed with leaf-stalks, &c. C. angustifolia is also cultivated in the extreme south of India, and there affords larger leaves, which are known in commerce as Tinnevelly senna. This variety is carefully collected, and consists almost exclusively of leaves of a fine green colour, without any admixture of stalks. It is exported from Tuticorin.
Senna appears to have been introduced into Europe about the 9th century by Arabian physicians, by whom, however, the pods seem to have been preferred to the leaves. The medicinal activity of senna leaves appears to be due to a very unstable colloid glucoside to which the name of cathartic acid has been given. It is readily decomposed by a temperature much below 100° Fahr. (Pharm. Jour. Trans., [3], xv. p. 704), and hence cold preparations of senna are the most active. In the free state it is soluble in dilute alcohol and in water, forming a brown solution, but is almost insoluble in strong alcohol and entirely so in ether and chloroform. Combined with ammonia it forms an active purgative. Two bitter principles named sennacrol and senna-picrin have been extracted from senna by Ludwig; the former is soluble and the latter insoluble in ether. A yellow colouring matter has also been obtained from senna, but it appears probable that it is only a decomposition product of cathartic acid. Senna must be included among the irritant purgatives, since cathartic acid has no aperient effect when injected into the blood. Owing to its colloid character, it is absorbed with difficulty, and its action is thus exerted throughout the greater part of the intestinal canal.
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SENNACHERIB. See Babylonia, vol. iii. p. 187, and Israel, vol. xiii. p. 413 sq.
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king of Assyria, son and successor of Shalmaneser. He began his reign A. M. 3290, and reigned only four years. Hezekiah, king of Judah, having refused to pay him tribute, though he afterward submitted, he invaded Judea with a great army, took several forts, and after repeated, insolent, and blasphemous messages, besieged Jerusalem; but his army being suddenly smitten with a pestilence, which cut off a hundred and eighty-five thousand in a single night, he returned to Nineveh, where he was murdered in the temple of Nisroch by his sons Adrammelech and Sharezer, and was succeeded by his other son, Esar-haddon, 2 Kings xix, 7, 13, 37.
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