Piperine

Piperine, along with its isomer chavicine, is the alkaloid responsible for the pungency of black pepper and long pepper. It has also been used in some forms of traditional medicine and as an insecticide.

Preparation

Piperine is commercially available. If desired, it may be extracted from black pepper using dichloromethane. Aqueous hydrotopes can be used in the extraction to result in high yield and selectivity. The amount of piperine varies from 1-2% in long pepper, to 5-10% in commercial white and black peppers. Further, it may be prepared by treating the solvent-free residue from an alcoholic extract of black pepper, with a solution of potassium hydroxide to remove resin (said to contain chavicine, an isomer of piperine) and solution of the washed, insoluble residue in warm alcohol, from which the alkaloid crystallises on cooling.

Reactions

Piperine yields salts only with strong acids. The platinichloride B₄•H₂PtCl₆ forms orange-red needles. ("B" denotes one mole of the alkaloid base in this and the following formulae.) Iodine in potassium iodide added to an alcoholic solution of the base in the presence of a little hydrochloric acid gives a characteristic periodide, B₂•HI•I₂, crystallising in steel-blue needles, mp. 145 °C.