C17H19NO3 = 285.162.
Piperine, C17H19NO3, is an alkaloid obtained from Piper nigrum, Linn., and other plants belonging to the N.O. Piperaceae. It is official in the U.S.P. It occurs in the form of colourless or slightly yellowish, glistening, prismatic, odourless crystals, tasteless at first, but later developing pungency. The alcoholic solution is neutral to litmus, and has a peppery taste. Optically inactive. Melting-point, 130°. On ignition, it emits alkaline vapours and burns without leaving any residue. It is a very weak base, and its salts are decomposed by water. By dry distillation with soda lime piperidine is obtained. Concentrated sulphuric acid dissolves it with the formation of a blood-red colour, which disappears on dilution with water. This is said to be a delicate reaction. Heated with alcoholic potassium hydroxide, it is converted into piperic acid and piperidine, the latter recognised by its peppery odour, the former by its melting-point of 215°. On adding a crystal of piperine to sulphuric acid containing about half its volume of formaldehyde solution, a permanently green liquid is formed. On heating with nitric acid, it is coloured first orange, then red, the acid acquiring a yellow colour, deepening to reddish as the crystals dissolve. The addition of an excess of potassium hydroxide solution produces a yellow colouration which becomes blood-red on boiling.
Almost insoluble in water; soluble in alcohol (1 in 30); boiling alcohol (1 in 1); in ether, chloroform, benzol, hot glacial acetic acid, or volatile oils.
Action and Uses.—Piperine is employed as an antipyretic and antiperiodic in malarial conditions, and as a carminative in dyspepsia. For its action as a febrifuge, doses of 6 decigrams (8 grains) are administered in a cachet or suspended in water. As a stomachic it is given in small doses in pills, sometimes with rhubarb, nux vomica, etc.
Dose.—1 to 6 decigrams (2 to 8 grains).