Synthesis of piperine derivatives

Abstract

The berries of black pepper (P. nigrum) are well known for its pungent smell and biting taste. Piperine which is one of the major amide present in P. nigrum contributes to the medicinal properties of the species. Extraction of the berries through maceration process followed by isolation of piperine via treatment with ethanolic potassium hydroxide successfully produced piperine (5-(1,3-benzodioxol- 5-yl)-1-(1-piperidinyl)-2,4-pentadien-1-one). Several chemical modifications have been carried out to derivatize piperine. Acetal cleavage has afforded 5-(3,4- dihydroxyphenyl)-1-(1-piperidinyl)-2,4-pentadien-1-one. Basic hydrolysis of piperine then afforded piperic acid (5-(1,3-benzodioxol-5-yl)-2,4-pentadienoic acid) which had been used as the precursor to synthesize an aliphatic amide (5-(1,3- benzodioxol-5-yl)-1-(n-butylamine)-2,4-pentadien-1-one), an ester (5-(1,3- benzodioxol-5-yl)ethyl-2,4-pentadienoate) and an acid (1,3-benzodioxol-1-yl)- methanoic acid). The pure piperine and derivatives were characterized by using infrared spectroscopy (IR), nuclear magnetic resonance (NMR) and mass spectrometry (MS). The screening for antimicrobial properties of the compounds were also carried out by using disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods against Grampositive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Piperine and all derivatives were found to be active towards Gram-positive bacteria with MIC value ranging from 225-900 µg/mL.