Wrightia. Wrightia zeylanica. Conessi bark.
Wrightia, Wrightia zeylanica R. Br. (W. antidysenterica R. Br.) (Fam. Apocynaceae.)—Under the names of Conessi bark, Tellicherri bark, and Codaya pala, a spongy, rusty-colored, bitter bark of this apocynaceous tree was formerly used in Europe as a remedy in dysentery and diarrhea, and is said still to be largely employed by the native practitioners of India. Stenhouse obtained from the seeds, besides a fixed oil which they contain in large quantity, a non crystalline alkaloid, called by him wrightine, which seems to be the same substance previously described by Hains under the name of conessine. (P. J. (2), vi, 432.) The alkaloid conessine is now a commercial product prepared by Merck, and the formula C24H40N2 is given it. It occurs in delicate, white, interlaced masses of crystals, melting at 121° C. (249.8° F.), sparingly soluble in water, readily so in alcohol. A small quantity rubbed with a few drops of concentrated sulphuric acid affords on the addition of nitric acid a golden and finally orange-yellow color. We are not aware that the medicinal properties of this have been investigated.
A species of the allied genus Holarrhena (H. africana A. DC.., is stated by German missionaries to be used in parts of tropical Africa in dysentery. Polstorx and Schirmer (Ber. d. Chem. Ges., 1886. 78) prepared the alkaloid both from Holarrhena africana and from Wrightia zeylanica, finding it to be identical in the two cases. When oxidized by iodic acid in sulphuric acid solution, conessine is changed to oxyconessine, (C12H20NO.)2.