Discrimination of Piper longum and Piper retrofractum fruits by chromatographic fingerprint analysis

In the Pharmacopoeia of the Peoples Republic of China the fruits of Piper longum L. are considered as “Bibo“. According to our investigations with a series of commercial batches of bibo, most of the samples were derived from Piper retrofractum Vahl. although this is not an accepted substitute. Several books dealing with the Chinese Materia Medica clearly describe properties of Piper retrofractum under the chapter “Piper longum L.“ and even illustrate them with pictures of this allied species.

The macroscopic description of the drug in the pharmacopoeia does not unambiguously allow the destinction of both species. Therefore chromatographic methods have been developed for a clear identification. Peaks have been identified by LC-MS [1]. The HPLC-fingerprint of P. retrofractum only shows one predominant peak (piperine) and a very small one of retrofractamide A. In contrast to the chromatogram of P. longum retrofractamides B and D, and N-isobutyl-2E,4E-octadecadienamide can be detected. The HPLC-chromatogram of Piper longum shows a homogeneous distribution of numerous peaks, with piperine and pellitorine as the predominant compounds.

Piper retrofractum and Piper longum can also easily be distinguished by TLC under UV_254nm and UV_365nm [2].

References: 1. Stöhr, J. et al. (2001), J. Ethnopharmacol. 75:133–139. 2. Wagner, H. et al. (2006), Chinese Drug Monographs and Analysis, in press.