Solid state NMR study of the bioenhancer piperine, supported by GIPAW DFT calculations

Abstract

Piperine, an alkaloid found in black pepper fruits, has the properties of promoting the absorption of other substances (e.g. curcumin), therefore it is used in solid forms of dietary supplements as an additive increasing bioavailability. The aim of the study was to analyze piperine in a solid state and then to use it in the analysis of solid dietary supplements with the addition of piperine as an absorption promoter. The ¹³C CP MAS NMR spectra were recorded using variable contact time and dipolar dephasing experiment. The calculation of theoretical chemical shift values for three polymorphic forms of piperine allowed us to create a database of NMR parameters enabling the identification of polymorphic forms based on the analysis of the ¹³C CP MAS NMR spectrum. Additionally, the analysis of cross-polarization kinetics parameters was performed. Then, the ¹³C CP MAS NMR technique was used to confirm the authenticity and determine the presence of curcumin in dietary supplements containing curcumin with the addition of piperine. The presence of piperine could be confirmed even when the mass content of piperine was 70 times lower than that of curcumin. This method can be used to test the quality of dietary supplements containing the addition of piperine as an absorption promoter.

Keywords: Food supplements; GIPAW-DFT; Piperine; ssNMR.