The internal chemical construction of all the alkaloids is extremely complex; for many it is unknown. Most are tertiary bases; a few are similar to the secondary amines in structure. Ammonia bases are also present in many. Many alkaloids acted on by strong alkalis are broken up into two components, a basic body and a nitrogen free, usually aromatic acid. Most of the alkaloids react similarly to oxidiz ing agents; nitric acid, chromic acid, potassium ferrocyanide and potassium permanganate are the most active. The last makes an efficient chemical antidote for many of them. A few alkaloids have been made synthetically. In the making, however, a related base has been neces sary.
Physiologically the alkaloids are for the most part very active. Some have very little berberine, for example, while aconitine is one of the most toxic of substances. Nearly all of them have a marked affinity for nerve struc tures, on which a few have markedly poisonous action: some of them attacking the sensory nervous elements more particularly (aconitine, cocaine) ; others exerting their greatest activity on the motor nervous structures, sometimes in the muscle plates (coniine, curarine) causing paralysis; others in the motor cells in the anterior horn of the spinal cord (strychnine). Still others exert their influence on the nerve cells of the brain (morphine, hyoscyamine).
History.— The history of the discovery of the alkaloids is about 100 years old. Derosne of Paris first isolated from opium in 1803 a salt aof opium," as he termed it. This was a mixture of morphine and narcotine, and in 1806 Sertiirner, a pharmacist of Hanover, first defi nitely discovered morphine. It was not until
1817, however, that the discovery was noticed. Following this in rapid succession different alkaloids were isolated — narcotine and emetine, in 1817, veratrine and strychnine, in 1818, bru cine and piperine, in 1819, caffeine, cinchonine and quinine, in 1820, and by 1835 at least 30 alkaloids were known. At the present time there are more than 200 known, and new ones are being discovered rapidly; detailed study of more important alkaloids will be found under their respective heads. See ANIMAL ALKALOIDS ; PLANTS; POISONS; and separate articles on the more important alkaloids under their special names.
Bibliography.—