Studies on the Pungent Constituents in Black Pepper (Piper nigrum L.)

Part II. Photochemical changes of piperine

Abstract

The structure of the piperine dimer which is easily obtained by irradiating the suspension of extremely minute crystals of piperine (made by pouring its alcohol or acetone solution into a large volume of water) was investigated. From IR, UV, NMR and MS informations, piperine dimer was found to be all asymmetric four membered ring structure combined head to head bf two piperines; that is 1-(3, 4-methylenedioxyphenyl)-2-(3, 4-methylenedioxycinnamyl)-cyclobutane-3-carboxylic acid-4-(β-acrylic acid)-dipiperidide.